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The aim of this research was to evaluate the production of glass ceramics from novel combinations of fly ash, glass cullet, blast furnace slag and copper slag solid wastes. The CaO/SiO2 molar ratios of the mixtures were 0.17–0.39. Glass ceramics were produced by thermal treatment of frits obtained by quenching in water. The results show that samples with a high Fe2O3 content (>4 wt%) are not adequate for glass-ceramic formation, as a result of the effect of ferric iron, Fe3+, which increases the network connectivity, on the stability of the glass. The mechanical properties of the ceramic materials were as follows: elastic modulus of 97.8–106 GPa, Vickers microhardness of 612–701 MPa, fracture toughness of 0.45–0.84 MPa m1/2, and friction coefficient of 0.57–1.0. For the glass ceramics, the mass loss did not exceed 1% in NaOH and 15% in HNO3 as a result of the crystalline phases formed. The ceramic materials developed in this research could be considered for potential applications in the production of glazes for residential or industrial tiles and coatings, among others.

In this study, the crystallization behavior of Al86Ni8Y6 upon rapid cooling from the equilibrium melt is investigated and the crystalline phases that compete with the glass formation are identified. Al86Ni8Y6 is one of the best glass formers in the ternary Al-Ni-Y system. Contrary to previous studies suggesting α-Al as the primary phase upon quenching, this study reveals that glass formation is strongly restricted by the formation of the primary precipitating ternary intermetallic compound Al23Ni6Y4. The nucleation of Al23Ni6Y4 appears to be triggered by yttrium oxide particles present in the melt acting as heterogeneous nucleation sites. Once the primary phase Al23Ni6Y4 has been formed, further crystallization of the Ni and Y depleted melt occurs as α-Al. The corresponding results are shown and discussed with respect to their effects on the glass formation.

Background Distortion arises during machining of metallic parts from two main mechanisms: 1) release of bulk residual stress (BRS) in the pre-form, and 2) permanent deformation induced by cut tools. Interaction between these mechanisms is unexplored. Objective Assess this interaction using aluminum samples that have a flat surface with variations of BRS, where that surface is subsequently milled, and we observe milling-induced residual stress (MIRS) and distortion. Methods Plate samples are cut from two kinds of large blocks, one kind stress-relieved by stretching and a second kind solution heat treated, quenched and aged. The BRS field in the plates is known from a recent series of measurements, being small in the stress relieved plates (within ±20 MPa) and large (±100 MPa) in the quenched plates, varying from tension to compression over the surface that is milled. MIRS is measured following milling using hole-drilling. Distortions of thin wafers cut at the milled surfaces are used to elucidate BRS/MIRS interactions. A finite element (FE) model and a strength of materials model are each used to assess consistency between wafer distortion and measured MIRS. Results Milling in samples with high BRS magnitude changes the directions of MIRS and distortion relative to the milling direction, with the direction of maximum curvature rotating toward or away from the milling direction depending on the sign and direction of BRS. High magnitude BRS was also found to increase the wafer peak arc height, nearly doubling the amount found in low BRS samples. Conclusion Measured residual stress and observed wafer distortion both show interactions between MIRS and BRS. Stress analysis models show that the differences in measured MIRS are consistent with the differences in observed distortion.

The metastable α' phase and dislocation characteristics (e.g., density and constituents) are of vital importance for the mechanical responses of (α+β) titanium alloys. In this work, to reveal the in-depth decomposition mechanisms of dislocations and metastable α' and their influences on mechanical properties in a Ti-6Al-4V (α+β) alloy, the thermal stability of different microstructures tailored by various cooling approaches were investigated utilizing scanning electron microscope, electron backscattered diffraction, transmission electron microscope and X-ray diffraction line profile analysis. The results showed that the initial characteristics of α' and α laths and dislocation density were influenced by the cooling methods remarkably. The thermal stability of Ti-6Al-4V alloy increased with decreasing cooling rate. The improvement in thermal stability can be ascribed by the decrement in dislocations, partitioning of the alloying elements and grain orientations variation of the α' lath and α phase. It is also found that the plastic strain accommodation of β→α' transformation was dominated by dislocations. During stabilization annealing treatments, the , and dislocations simultaneously decomposed. The decomposition of dislocations and metastable α' phase during various stabilization annealing and the particular twins and stacking faults microstructures formed during quenching have a great influence on the properties of the studied Ti-6Al-4V alloy.

Additive manufacturing of material systems sensitive to heat degradation represents an essential prerequisite for the integration of novel functionalized material systems in medical applications, such as the hybrid processing of high-performance thermoplastics and gelling polymers. For enabling an inherent process stability under non-isothermal conditions at reduced ambient temperatures in laser-based additive manufacturing, maintaining a homogeneous layer formation is of vital significance. To minimize crystallization-induced deflections of formed layers while avoiding support structures, the temporal and spatial discretization of the melting process is combined with the subsequent quenching of the polymer melt due to thermal conduction. Based on implementing superposed, phase-shifted fractal curves as the underlying exposure structure, the locally limited temporal and spatial discretization of the exposure process promotes a mesoscale compensation of crystallization shrinkage and thermal distortion, enabling the essential homogeneous layer formation. For improving the understanding of local parameter-dependent thermal intra-layer interactions under non-isothermal processing conditions, geometric boundary conditions of distinct exposure vectors and the underlying laser power are varied. Applying polypropylene as a model material, a significant influence of the spatial distance of fractal exposure structures on the thermal superposition of distinct exposure vectors can be derived, implicitly influencing temporal and temperature-dependent characteristics of the material crystallization and the emerging thermal material exposure. Furthermore, the formation of sub-focus structures can be observed, contributing to the spatial discretization of the layer formation, representing a decisive factor that influences the structure formation and mesoscopic part properties in non-isothermal powder bed fusion of polymers. Consequently, the presented approach represents a foundation for the support-free, accelerated non-isothermal additive manufacturing of both polymers and metals, demonstrating a novel methodology for the mesoscale compensation of thermal shrinkage.

This paper reports the quenching process optimization and wear properties of T6-treated 2024, 6063, and 7075 aluminum alloys. 25 and 65 degrees C were selected to determine the effect of elevated temperatures of the quenching medium. The hardness of samples was measured after T6. The wear behavior of alloys was compared with some parameters such as weight loss, volume loss, and wear rate by abrasive wear tests under dry sliding conditions. Surface roughness measurements were carried out to determine the quality of the worn surfaces. Also, wear mechanisms were determined with the wear map. Wear properties and microstructure were analyzed using scanning electron microscopy and energy-dispersive x-ray spectroscopy. As a result, unlike 2024, the hardness of 6063 and 7075 alloys decreased with increasing quenching temperature. The wear rate decreased in the 6063 and 7075 alloys as the quenching temperature increased, but increased in the 2024 sample. Plastic deformation, fatigue, micro-shearing, micro-fracture and delamination mechanisms were determined depending on the changing load and sliding distances in wear. Surface roughness significantly improved with constant weight loss, hardness, volume loss, and wear rate parameters, particularly at high application forces.

Ultrahigh-strength quenching and partitioning (Q&P) steels have attracted strong interests in the auto manufactory, while the comprehensive understanding in the microstructure and mechanical behavior of their welded joints is highly needed to enrich their applications. In the present work, it is designed to make an insight into these imperative conundrums. Equal strength Q&P 1180 steel joints to parent metal were successfully fabricated via friction stir welding (FSW) technique under different parameters. Apparent hardening and softening were observed in stir zone (SZ) and heat-affected zone (HAZ) respectively, whose microstructures strongly depended on the peak temperature and cooling rate during welding. The formation of fresh martensite was the main mechanism for the SZ hardening, while the decomposition of metastable phases played key roles in the microhardness drop of the HAZ. A heat source zone-isothermal phase transition layer model was proposed to clarify the impregnability of the joint strength under parameter variation. The dual-phase structure, nano-carbide particles, tempered initial martensite, and ultrafine-grained ferrite synergistically improved the strain hardening ability of the HAZ, which eventually resulted in the equal strength FSW joints.

To investigate the effect of surface-modified nanoparticles (NPs) on the inclusion refinement and microstructure evolution, deoxidized experiment ingots with different amounts of modified NPs were manufactured under different cooling conditions. Laser scanning confocal microscope (LSCM) was hereby used for in-situ observation of the phase transition and microstructural evolution during heat cycle process. The results revealed that the inclusion size was always smaller under water quenching than under air cooling, and the number of inclusions was greater under water quenching. After NP addition, the nucleant inclusions were identified as MgAl2O4 spinel and irregular TiN inclusion from SEM-EDS measurement and equilibrium calculations using Factsage thermodynamic software. The higher cooling rate under water quenching resulted in less polygonal ferrite decrease and the formation of bainite in the steel. The LSCM experiments showed that ferrite side plates (FSP) always formed on the boundary prior to the formation of acicular ferrite (AF) on the intragranular inclusions, and the start transformation temperatures of FSP and AF phases both lowered after NP addition. The higher cooling rate and NP addition contributed to AF formation and increased the degree of interlocking of the AF phase. Finally, the relationship between the characteristics of inclusions and the kinetics of AF was investigated.

Silicon is an essential alloying element in quenching and partitioning (Q&P) steels, because it is known to suppress carbide precipitation during partitioning step and promote carbon partitioning to stabilize austenite. When 2 wt% Si was added to 10Mn-2Al-0.2C steel, the size and fraction of the carbides formed during partitioning became smaller than in the Si-free counterpart. Moreover, the suppression of carbide formation promoted C partitioning into austenite as expected. However, austenite stability was always lower with Si under the equivalent partitioning condition because Si effectively decreased the stacking fault energy of austenite. As partitioning progressed, the both yield and tensile strengths of the Si-added steel exceeded that of the Si-free steel with the similar ductility level. This was because Si was an effective solid solution strengthener, and the austenite in the Si-added steel exhibited the appropriate stability to gradually transform into martensite throughout the deformation. The resulting strengthening effect compensated for the softening caused by martensite recovery. Consequently, strain hardening rate decreased continuously throughout deformation, which resulted in high tensile strength and ductility.

The effects of the Zn/Mg ratio on the precipitate behavior and mechanical properties of Al-Zn-Mg-Cu alloys at different quenching rates were investigated by a Jominy end-quench test, tensile test and microstructural analysis. The results show that the hardness and strength of the aged alloys clearly decrease with increasing quenching distance (D). Additionally, the alloy with a Zn/Mg ratio of 5.42 has a more obvious drop in yield strength than the alloy with a higher ratio of 7.09 when D is varied from 10 mm to 142 mm. During slow quenching, fewer equilibrium η phases are formed in the alloy with a higher Zn/Mg ratio of 7.09, and then a larger number of fine η′ phases precipitate during subsequent aging, which reduces the quench sensitivity of the alloy.

Nitrogen is an alloying element that can significantly improve the yield strength of steel by means of interstitial solid solution strengthening. The effects of quenching temperature on the evolution of second phase and grain size were investigated, as well as tensile properties, impact energy and hardness of a new nitrogen-alloyed Fe-Cr-Mo-V-N steel. The results show that with the increase of quenching temperature, the number and size of the second phase decrease as the high temperature promotes the dissolution and refinement of the second phase. For instance, the number of second phase M23C6 particles decreases gradually with temperature increasing. When the quenching temperature reaches 1050 °C, the grain is refined. Under the same tempering treatment, with the increase of quenching temperature, the tensile properties, impact energy and hardness increase first and then decrease. When the quenching temperature is 1050 °C and the tempering temperature is 180 °C, the obtained mechanical properties are the best. Under this condition, the tensile strength at room temperature is 2110 MPa, the yield strength is 1620 MPa, and the impact energy is 29.1 J, respectively.

55Cr17Mo1VN high nitrogen martensitic stainless steel is usually applied to the high-quality mold, which is largely produced by the pressurized electro slag remelting process. The microstructure evolution of quenching and tempering heat treatment were investigated and an optimal heat treatment process to achieve excellent mechanical properties was found out. The main precipitates in the steel included carbon-rich type M23C6 and nitrogen-rich type M2N. With increasing austenitizing temperature, the equivalent diameter of the precipitates got fined, and retained austenite content increased significantly when the austenitizing temperature exceeded 1020 °C. The fracture mode gradually changed from brittle fracture to ductile fracture with increasing tempering temperature from 200 to 550 °C. The experimental steel tempered at 350 °C achieved a good combination of hardness (60.6 HRC) and strength (2299.2 MPa) to meet service requirements. Flake M23C6 precipitated along martensite lath boundaries and the secondary hardening phenomenon occurred when the tempering temperature was 450 °C. Due to the high nitrogen content, M2N precipitated from the inside of laths and matrix when tempered at 550 °C.

40Cr is essential to steel for the manufacture of hardened gears, and optimizing its laser quenching process will be of great significance for gear wear and life extension. However, the complete reliance on the experimental trial-and-error approach does not effectively reveal the mechanism of the evolution of the laser quenching process in disk laser. Numerical simulation provides an effective way to obtain the transient evolution of the laser quenching process. In this paper, the temperature changes physical parameters of the quenched material are calculated based on the CALPHAD method. Establish a thermo-elastic–plastic multi-field coupling model for the laser hardening process of the disk laser 40Cr gear steel. Perform the numerical calculations on the transient temperature, martensite phase fraction, and the transformation-induced plasticity stress evolution of the 40Cr laser hardening process. Focus on the mechanism of the mutual coupling between phase change behavior and plastic strain. Calculations show that there is heat accumulation during quenching, with a peak temperature of 1448 K. Plastic stress has a “hump” distribution, with a peak value of 834 MPa, which is 1.25 mm from the center of the focal point. The experimental analyses of the 40Cr gear steel quenching microstructure and hardness distribution state by the Axioskop2 scanning electron microscope, the KEYENCE VH-Z100R super depth of field 3D microscope, and the Q10M microhardness tester reveal the mechanical behavior of the material and the phase hardening law during the quenching process. That provided an essential theoretical basis for effective prediction on quenching residual stress and optimizing industrial production parameters.

As a part of ongoing work on metal droplet dephosphorization, this study specifically investigated the effect of slag basicity (V ratio) by employing time lapse sampling while monitoring simultaneous decarburization using a constant volume pressure increase technique (CVPI) with X-ray fluoroscopy. The dephosphorization kinetics of droplets with two different initial carbon concentrations (2.51 and 0.007 wt pct), were tracked by quenching and analyzing droplets after different reaction times. The reaction kinetics were further elucidated by combining the decarburization rate of the droplet, measured via CVPI with the bloating behavior of droplet observed in-situ by X-ray fluoroscopy. The results showed that for high carbon droplets the dephosphorization rate increased with increasing slag basicity largely due to the increasing droplet decarburization rate, which enhanced mass transport of phosphorus by CO bubble stirring. Further increasing slag basicity increased the peak decarburization rate, but did not appear to further increase droplet dephosphorization. In low carbon droplets, the dephosphorization rate was also increased with increasing slag basicity because of the higher phosphorus partition ratio and larger mass transfer parameter $$kA$$ resulting from the faster oxygen transfer in the slag causing an increase in the interfacial area for reaction.

A superior combination of yield strength (1001 MPa) and − 20 °C impact toughness (166 J) was obtained in Nb–V–Ti-microalloyed Ni–Cr–Mo–Cu steel treated by direct quenching and tempering route (DQT). The tested steels treated by DQT route and re-austenitization and tempering route (QT) were compared with each other in terms of mechanical properties and microstructures characterized by optical microscopy, transmission electron microscopy, X-ray diffraction, electron back-scattered diffraction method and so on. Strength and Vickers hardness of the tested steel treated by the above two routes vary with isothermal aging temperature (400–600 °C), shown as under-aged state, peak-aged state and over-aged state. All DQT specimens show higher strength and Vickers hardness than QT specimens with the same aging condition. Furthermore, the largest difference of yield strength between DQT and QT specimens was shown in DQT600 and QT600 specimens. DQT600 or QT600 specimens refers to direct quenched (DQ) or quenched (Q) specimens isothermally aged at 600 °C. The main disparities in quenched microstructure between DQ and Q specimens are mainly in morphology of prior austenite grains, dislocation density of martensite matrix and solution amount of Nb and Mo elements dissolving in martensite matrix, which play key roles in affecting microstructure and mechanical properties of DQT and QT specimens. Higher dislocation density of matrix and finer average diameter of both MC (M is any combination of Nb, Mo and V) and Cu-rich particles were shown in DQT600 specimens than in QT600 specimens. Strengthening from dislocations and nanosized MC and Cu-rich particles mainly leads to the largest difference of yield strength between DQT600 and QT600 specimens. In addition, strong dislocation strengthening and precipitation strengthening in DQT600 specimen also elevated its ductile-to-brittle-transition-temperature, compared with QT600 specimen.

Instead of conventional quenching and tempering, fast austenitization from an initial microstructure of lamellar pearlite followed by quenching and tempering was carried out, leading to the formation of inhomogeneous microstructure. It comprised different morphologies of lath martensite and retained austenite (RA). The effect of tempering temperature on microstructure evolution and tensile properties was systematically investigated. With increasing tempering temperature from 150 to 250 °C, transition carbides gradually coarsened and their amount increased, the dislocation density in martensitic laths gradually decreased, and RA fraction decreased from 10.9% to 2.2%. The precipitation and dislocation strengthening can ensure a high strength, while RA can ensure a good ductility, leading to a simultaneous increase in the strength and ductility when decreasing tempering temperature. Specifically, the best combination of tensile properties (ultimate tensile strength of 2133 ± 41 MPa and total elongation of 11.1% ± 1.3%) was achieved after tempering at 150 °C.

This work concurrently investigates the microstructure evolution and stress state during continuous cooling of 1045 steel gear parts. A finite element algorithm was developed by two-way coupling of microstructural and thermal fields. Thermal coefficients were correlated to microstructural evolution, and a phase transformation kinetics model was considered to be both temperature and time dependent. Magee's rule was chosen for martensitic transformation modeling to incorporate the effect of stress state on microstructural field. The dilation curves for the benchmark sample show that martensite starting temperature increases when the stress state is considered in microstructure modeling. To determine the validity of the presented model, a cylindrical specimen was quenched in water and oil media, and their predicted microstructures were compared with experimental results. A reasonable harmony between simulated and experimental results was observed. The simulation was then performed for internal gear parts quenched in oil and water media. The simultaneous monitoring of microstructure and stress evolution during continuous cooling of an internal gear part was conducted. It was shown that simultaneous and separate transformations occurring between the tooth and root region have a determining role in the sign of stress for internal gear parts. Lastly, based on monitoring of different phase transformation scenarios occurring during water and oil quenching, a hybrid quenching was proposed to increase martensite volume fraction at the tooth region of an oil-quenched sample without altering the microstructure at root region.

The first part of this work was to explore the development of residual stresses in I-4 and V-6 engine blocks made of B319.1 alloy using the sectioning technique. The results suggest that there is refinement in the microstructure due to an increase in cooling rate along the cylinder. The developed residual stresses were found to be tensile for both I-4 and V-6 engine blocks. Furthermore, the variation in the developed residual stresses was found to be insignificant. The results also indicate that air cooling produced the highest residual stresses compared to warm water and cold water quenching. Solution heat treatment and freezing (−30 oC) led to the maximum amount of residual stress relaxation where 50% of the residual stresses were reduced after the solution heat treatment step. Aging time and aging temperature are directly proportional to the residual stress relaxation. Correlations between alloy hardness and the evolved residual stress have been established. In the second part, residual stresses were obtained from the milled surface of a rectangular workpiece (30 × 172 × 302 mm, five blocks/alloy for five studied alloys). Thirteen layers of material were removed from each block, where each layer consisted of ten paths, and the depth of cut was 1.35 mm, using fresh and dull inserts. In this case, measurement of residual stresses was carried out on the blocks at the end of the milling process, using the X-ray technique. All stresses were of tension-type compared to compression type in the un-machined shoulders. Due to the high applied forces required when using dull inserts, the resulting residual stresses were almost twice that generated by new inserts in spite of the large difference in the machining distance.

The original magnesium slag has poor desulfurization activity, so modification treatments are needed to improve its desulfurization activity. In this article, magnesium slag was modified by quenching hydration. The crystal structure and morphology characteristics were obtained by XRD and TEM. And to further understand the relationship between crystal structure and desulfurization performance, desulfurization experiments were carried out by TGA. A theoretical basis for future development of desulfurization methods was provided, which could not only alleviate the disposal problem but also help control SO2 pollution. The results showed that the naturally cooled magnesium slag was mainly composed of γ-C2S and β-C2S. The irregular coordination of Ca2+ in β-C2S was the main reason that the hydration activity of β-C2S was higher than that of γ-C2S. With the increase of quenching temperature, the β-C2S content increased continuously, promoting the formation of C–S–H with developed pore structure. With the increasing hydration temperature, the hydration reaction of β-C2S could be promoted, and more amorphous C–S–H could be generated. The hydration product C–S–H enhanced the physical adsorption capacity, and the increase of crystal structure defects enhanced the chemical adsorption capacity. At 950 °C quenching temperature and 90 °C hydration temperature, the desulfurization activity was the highest.

The effects of annealing before normalizing and different cooling ways, i.e., air cooling, quenching, and water mist cooling after normalizing on the toughness of G115 steels were investigated. The impact tests showed that the annealed samples had better toughness compared to the unannealed samples for three cooling ways. Microstructure observations revealed that the annealed samples had a more uniform grain distribution, smaller size and area fraction of M23C6 particles along the grain boundaries, and lower dislocation density than those in the unannealed samples, which performed together for good toughness. Among three cooling ways, air cooling gave the best toughness due to the smallest occupancy of M23C6 particles in the grain boundaries. Thus, the combination of annealing conducted before normalizing and air cooling selected after normalizing can improve the toughness a lot of G115 steels.

Quenching from sintering temperature enhances the depolarization temperature (Td) in Na1/2Bi1/2TiO3-based ceramics without significant deterioration of piezoelectric properties (d33). In this work, quenching effects in an ergodic relaxor 0.97(0.94Na0.5Bi0.5TiO3–0.06BaTiO3)–0.03AgNbO3 (NBT–6BT–3AN) were investigated based on structure, ferroelectric, and dielectric properties. The ergodicity to nonergodicity transition was obtained by quenching NBT–6BT–3AN above 1000 °C. The temperature stability of the quenching-induced nonergodicity was examined by annealing the quenched sample at 300 °C and 600 °C. The effect of oxygen vacancy on ergodicity to nonergodicity transition was investigated by comparing ferroelectric and electrostrain responses of the quenched and nitrogen-atmosphere-annealed samples. The influence of quenching on the structure including the average crystal structure, phase fraction and lattice distortion and the local structure including bond lengths and ordering of ions was analyzed. The ergodicity to nonergodicity transition upon quenching is ascribed to the contribution of the off-centered Bi3+ ions and ordered local structure.

The reinforcing bar (rebar) produced by Tempcore process had tempered martensite structure on its surface, owing to quenching and tempering, and ferrite–pearlite structure at the core owing to slow cooling rate. Bainite, a low-temperature transformation phase, was observed in the transition area. Mechanical properties of the rebar are significantly influenced by area ratio and hardness of the tempered martensite. In this study, microstructure and area ratio of the tempered martensite of the rebar produced by the Tempcore process were predicted using finite volume method and a continuous cooling transformation diagram. The area ratio of the tempered martensite was predicted with error range of ± 6%. Furthermore, association between the microstructure and hardness was determined by a non-isothermal tempering experiment. The hardness of the tempered martensite was successfully predicted using the tempering temperature with R-squared 98%. The proposed methodology can be effectively used to control the mechanical properties of the rebars.

Tungsten bronze coatings and films have attracted global attention for their applications in near-infrared (NIR)-shielding windows. However, they are unstable in strong ultraviolet, humid heat, alkaline and/or oxidizing environments and are difficult to be coated on glass surfaces with complex shape. Here, we address these limitations by doping sodium tungsten bronze (NaxWO3) into bulk glasses using a simple glass melting method. X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, TEM and SEM-EDS characterization confirmed the presence of sodium tungsten bronze (NaxWO3) functional units inside the 34SiO2-38B2O3-28NaF glass matrix. Because the functional units are well protected by the glass matrix, the fabricated glasses are stable under hot, humid, oxidizing conditions, as well as under ambient conditions, with no change after 360 days. The NIR-shielding performance of these glasses can be adjusted to as high as 100 % by varying WOx concentration (2−8 mol%) and quenching temperature (1000−1400 °C). With a content of 6 mol% WOx and a quenching temperature of 1000 °C, the bulk glass shows 63 % transmission of visible light and only 11 % transmission of NIR light at 1100 nm. Thermal insulation experiments show that the NIR-shielding performance of the glasses are far superior to commercial soda lime window glass or indium-doped tin oxide (ITO) glass, and comparable to cesium tungsten bronze coated glass. The novel bulk glasses have higher stability, simpler processing, and can be easily made into complex shapes, making them excellent alternative materials for energy-saving glasses.

In this study, forged EA4T steel specimens are subjected to three quenching temperatures of 800, 860, and 900 °C. Microhardness tester, laser scanning confocal microscopy, and scanning electron microscopy (SEM) are employed to measure microhardness, metallographic structure, and fatigue fracture characteristics, respectively. Heat treatment is found to be necessary to improve mechanical properties and fatigue behavior of initial forgings, and the effects of microstructure and defect are significant. Hence, considering variations of grain types and roughness between the initial forgings and heat-treated specimens, the fatigue property with defects are modified for roughness-affected axles by an improved KT diagram. The results indicate that the samples quenching at 860 °C achieved better fatigue performance due to the presence of fine polygonal ferrite (PF), bainite, as well as martensite. The fatigue life prediction error for the roughness-affected axle is between 16 and 18%. All of the fracture mechanism, grain size, and dislocation slip with different quenching temperatures affecting the fatigue performance are analyzed. Because the volume fraction of the martensite and bainite is significantly higher reaching 57.48% and more refined grains are obtained, the dislocation slip to the surface is delayed at the quenching temperature of 860 °C. Thus, the fatigue behavior is superior. Moreover, the yield strength increased by 22% compared to that of the initial forgings. Studies on the effect of the heat treatment process on fatigue behavior of EA4T steel contribute with a practical reference to the engineering application of high-speed rail axles.

As a modification of quenching and partitioning processing for martensitic steels to obtain mixed microstructures of martensite and austenite aiming at improving strength plasticity, the process of quenching and dynamic partitioning is much simple in practical, especially suitable for components with larger cross-sections. In this paper, a kind of air-quenched low-carbon steel was designed and prepared. The martensitic transformation behaviors at different cooling rates, the structure–property relationship and the strengthening–toughening mechanisms of testing steel under a different processing were explored. The results show that the testing steel exhibits good hardenability that fairly martensitic transformation occurs while it is cooled at the rate of 0.1~1.0°C.s-1. The microstructures of plate samples with 25~40 mm in thickness after air quenching are composed of lath martensite and strip-like retained austenite of about 5 vol.%. Once the air-quenched samples are tempered at 450°C, the volume fraction and thermal stability of retained austenite are further reinforced, and good comprehensive properties are obtained with Rp0.2≈1200 MPa, Rm≈1400 MPa, A≈18% and KV≈1000 kJ.m-2.

This study, concerns the improvement of the hardness and resistance to wear of the Ti-6Al-4V alloy surface by means of thermochemical treatment, for obtaining coatings on the Ti-6Al-4V alloy gives performance of resistance to wear phenomena. Three-thermochemical treatment time (2h, 4h, and 6h) was chosen for investigation of the effect of such treatment on this alloy. The hardness test under an indentation load of 50 gf with a Vickers pyramidal indenter revealed that the surface hardness is 335 Hv for the untreated samples. On the other hand the hardness reaches approximately 1500 Hv during gas cementation at 930 °C for variable times (2h, 4h, 6h) followed by quenching at 840 °C in an oil medium, which was accompanied by a significant improvement in wear resistance. The characterization of the modified surface layers was made by means of a microscopic analysis and by X-ray diffraction. The case-hardening made it possible to obtain a wear resistance greater than that of the alloy not treated, minimal loss of mass by dry friction and an improvement in roughness as well as a good coefficient of friction.

A systematic study of impact energy, microstructure, fracture section and residual stress of 27Co-Fe was carried out using charpy impact tester, metalloscope, scanning electron microscope and x-ray residual stress detector. The forged C27, C27R1 and C27R2 were held at 650 °C, 700 °C, 750 °C, 775 °C and 800 °C for 2 h, respectively, quenched with water and tempered at 300 °C for 2 h to test the impact energy. The impact energy of forged C27R1 increased to more than 50 J compared with 1.2 J of C27 and the impact fracture changed from brittle fracture to ductile fracture with dimples. Microcracks and microvoids were reduced. Ce increased the nucleation rate of 27Co-Fe, refined and homogenized the grain. It’s obvious when Ce content was 0.03 wt.%, the grain size decreased from 20.2 to 12.9 μm. The grain refinement trend decreased when the Ce content was 0.06 wt.%. After quenching and tempering, C27, C27R1 and C27R2 were basically increased to more than 50 J when quenching temperature was 700–750 °C. C27R2 was held at 800 °C for 2 h, quenched with water and tempered at 300 °C for 2h, 4h and 8h, respectively, to test impact energy and residual stress. The residual stress of C27R2 decreased from 547 to 281 MPa when the tempering time was 8 h, and the impact energy increased from 2.5 to 78 J.

In the present work, a novel medium carbon martensitic stainless steel (MCMSS) with an excellent combination of strength, ductility, and impact toughness was designed on the basis of quenching-tempering and partitioning (Q–T&P) technology. Q–T&P is an identical heat treatment with a standard quenching and tempering (Q–T) process but has the same role with quenching and partitioning (Q&P) on microstructure control, i.e., promoting carbon-rich retained austenite via inhibiting carbide precipitation. Results show that, without compromise on strength, the total elongation and room temperature impact toughness, i.e., 9.6 pct and 90 J cm−2, of the proposed alloy (23Cr13MnSi) increase by 14 and 110 pct, respectively, as compared to those of the commercial AISI 420. The significant improvement of ductility and impact toughness in the proposed alloy is mainly a result of the gradual transformation induced plasticity (TRIP) effects, which are caused by carbon-rich retained austenite with heterogeneous stability and carbide-free martensite formed in the Q–T&P process.

The present study has been undertaken to investigate the effect of alloying additions and high temperature T5-treatment consisting of high temperature direct aging after casting, on the microstructural characteristics of some Al-Si-based eutectic and near-eutectic alloys, typically used in the automotive industry. For comparison purposes and in order to estimate the effect of Mg, three sets of samples consisting of Al-11.9wt%Si (AS13, B413), Al-11.67wt%Si-0.22wt%Mg (AS10G) and Al-7.2wt%Si-0.44wt% Mg (AS7G06, A356) alloys have been first studied in the as-cast state. In order to examine the effect of heat treatments, three groups of alloys were investigated in two different states, namely: (i) after T6-treatment consisting of solutionizing at 540 °C for 10 hours, water quenching and then aging at 160 °C for 4 hours; and (ii) after high temperature T5-treatment consisting of annealing at 300 °C, 450 °C and 500 °C for different aging times in order to locate a possible peak hardness. Microstructural examination was carried out using optical microscopy, scanning electron microscopy, energy Dispersive Spectrometry (EDS), X-Ray Diffraction and Brinell-hardness measurements. Our as-cast alloys’ microstructure revealed that all the different intermetallic phases, such as the Q-Al5Cu2Mg8Si6 phase, the α-Al15(MnFe)3Si2, β-Al5-Fe-Si, π-Al8FeMg3Si6 and Al7Cu2Fe iron-rich compounds, as well as the Al2Cu and Mg2Si hardening precipitates, have been formed during solidification. Besides, X-rays diffraction patterns revealed that while some Al2Cu hardening precipitates have exhibited total dissolution, after solutionizing, the undesirable iron-rich phases have remained at least partially insoluble after the different heat treatments. A semi-quantitative X-Rays diffraction analysis, performed after the different heat treatments, has shed light on the interplay between the Fe-rich intermetallic compounds, denoting the transformation of the π-Al8FeMg3Si6 into the β-Al5FeSi phase on the one hand and between π-Al8FeMg3Si6 and Q-Al5Cu2Mg8Si6 phases in the precipitation and dissolution of Al2Cu and Mg2Si phases on the other hand. Both of the two processes, marking a certain interaction between the different intermetallic compounds, are observed to give rise to a significant release of Mg and Si solute atoms and to enhance the hardening precipitates volume fraction after heat treatments. It turns out that high temperature T5-treatment is more appropriate and even more efficient than the usual T6 one, in the sense that it yields a more significant amount of hardening precipitates giving rise to higher hardness peaks with just one step treatment.

The possibility of improving the mechanical and wear performance of steel rails with conventional compositions, near-eutectoid and without special alloying elements, using a two-step heat treatment was investigated. The heat treatment involved a first step involving quenching to a low temperature, near the Ms, maintaining at this temperature for a short time, followed by a second step at higher temperatures until complete transformation. The microstructures, tensile, and wear properties of the obtained products were characterized. The dilatation data confirmed that the remaining austenite was completely eliminated by the bainitic transformation at 400 °C for only 300 seconds, in the absence of alloying elements such as silicon without formation of carbide precipitates. The refined bainite-ferrite microstructure obtained by the two-step heat treatment significantly increased mechanical properties, as well as wear resistance measured using tensile and pin-on-disk tests. The bainitic ferrite structure exhibited approximately 20 pct higher hardness and about 53 pct less mass loss on pin-on disk test than the as-received pearlitic sample. Dilatometric and microstructural analysis using EBSD-electron backscattered diffraction techniques provided evidence that the two-step heat treatment increased the nucleation rate of the bainitic transformation and shortened the incubation time for transformation at the second step, at the same time increasing the density of crystallographic defects such as dislocations and grains boundaries. The proposed heat treatment, besides improving the mechanical properties and wear resistance, avoids the technological difficulties of using molten salt or metal for isothermal heat treatment of long products as rails.

To improve the properties of low-carbonization of MgO–C refractories, the introduction of composite additives is an effective strategy. Al2O3–SiC composite powder was prepared from clay using electromagnetic induction heating and carbon embedded methods. Further, the Al2O3–SiC composite powder synthesized by electromagnetic induction heating at 600 A was added into low-carbon MgO–C refractories (4 wt.%) to improve their properties. The results showed that when the addition amount of Al2O3–SiC composite powder is within the range of 2.5–5.0 wt.%, the properties of low-carbon MgO–C samples were significantly improved, e.g., the apparent porosity of 7.58%–8.04%, the bulk density of 2.98–2.99 g cm−3, the cold compressive strength of 55.72–57.93 MPa, the residual strength after three air quenching at 1100 °C of 74.86%–78.04%, and the decarburized layer depth after oxidized at 1400 °C for 2 h of 14.03–14.87 mm. Consequently, the idea for the rapid synthesis of Al2O3–SiC composite powder provides an alternative low-carbon MgO–C refractories performance optimization strategy.

The effect of ageing on the structure and mechanical properties of continuously cast and rolled sheet from aluminum alloy 6061 is studied. Atreatment regime involving 2-h water quenching from 550°C and six hours artificial ageing at 200°C is shown to provide the values of σr, δ, and HV equal to 318 MPa, 14%, and 127 HV0.1 respectively. The alloy fractures by a ductile mechanism after quenching and by a mixed mechanism after ageing. The average grain size after ageing is 0.09 nm, and over grain boundaries there is a large amount of Mg2Si nanosize inclusions and heat-resistant α-Fe phase that increase sheet mechanical properties.

The thermomechanical properties of shape memory alloy Ni50Ti50 are studied after equal channel angular extrusion, torsion at a pressure of 6 GPa with 0.5 and 2 turns, and subsequent heat treatment (quenching or annealing). Parameters of the thermoelastic phase transformation of specimens in different conditions are determined. X-ray diffraction analysis is performed. It is shown that an increase in the degree of the high-pressure torsional deformation to two turns increases the degree of specimen structure amorphization and critical stresses to 3000 MPa, while deformation up to half a turn makes it possible to increase reversible bending strain to 16% at stresses up to 1210 MPa.

Ni improves toughness in martensitic steels. However, the effect of Si on grain refining and toughness of martensitic steel for high-strength applications including armor grades has not been much studied, which can be also a cheaper alternative replacing Ni and without any micro-alloying addition. With this motivation, an initial laboratory study of a quenched and tempered high-Si steel (0.31C-1.25Si-1.19Mn-0.1Mo-0.29Ni) and low-Si steel (0.32C-0.49Si-0.61Mn-0.46Cr-0.1Mo-0.29Ni) showed that their full thickness Charpy impact energy at − 40 °C was 32 ± 3 and 15 ± 2 J, respectively, while their microstructures had maximum lath length 15 and 30 μm, respectively. Based on this, an industrial steel (0.30C-1.27Mn-1.23 Si-0.22 Mo-0.43Ni) was made through electric arc furnace—vacuum arc degassing—continuous casting route with low H2, O2 and N2 contents and hot rolled to 5.2-mm-thick coil, which finally processed to quenched and tempered plate. The air-cooled hot-rolled intermediate plate of 25 mm thickness revealed bainitic microstructure, while the slowly cooled hot-rolled coil sample showed banded microstructure consisting of proeutoctoid ferrite and pearlite. On the other hand, the ferrite bainitic microstructure was revealed when the steel was cooled at 1 °C/s through dilatometry using Gleeble 3500C. The bainitic microstructure at low cooling rate indicated high hardenability of this grade. The Ac3 transformation temperature determined by dilatometry was 850 °C. Based on this, oil quenching was carried out after heating at 895 °C for 7, 12 and 17 min, while low-temperature tempering was done at 250 °C for 60 min. The micrographs in these three heating conditions revealed fully martensitic microstructure consisting of fine laths. The hardness of plates varied in the range of 495-506 HBW after tempering at 250 °C for 1 h, while yield strength, tensile strength, percentage elongation and percentage of reduction in area varied in the range of 1500-1540, 1780-1820 MPa, 7.37-8.61 and 24.64-27.40, respectively. The Charpy impact energy of sub-size ½ thickness specimen varied closely in the range 11.5-13.8 J at − 40 °C and their corresponding fracture surfaces showed dimpled ductile rupture morphology that typically belonged to the upper shelf region of Charpy transition curve. The measured hardness, strength, elongation and Charpy energy are in accordance with the requirement of final product. Bright-field TEM image of the tempered steel showed the presence of fine laths and uniformly distributed needle-shaped fine carbides resembling e-Fe2.4C.

Residual stress developed after the quenching of aluminum alloys causes distortion during subsequent machining. The purpose of this study was to reduce the residual stress and improve mechanical properties by using a novel cryogenic treatment in an aluminum alloy, specifically, grade 2A12. The orthogonal test and relevant range analysis method were used to optimize cryogenic treatment parameters for improved distribution of residual stress in 2A12 alloy samples. The changes of microstructure were examined by scanning electron microscopy and transmission electron microscope. It was found that the residual stress in 2A12 alloy could be reduced up to 93%, by optimizing the cryogenic treatment parameters, and the reduction was mainly from grain refinement and uniformly distributed S' precipitates ascribing to the cryogenic treatment. The S' precipitates (Al2CuMg) were linked to the formation of Cu-Mg co-clusters, which were broadly equiaxed with no internal order.

Improving the strength values of low–medium-strength shipbuilding steels without changing the chemical properties will be very useful to meet the high-strength requirement in ships. Heat treatments and severe plastic deformation methods are the main methods used to increase the strength values of steel without changing the chemical structure. Considering the high improvement effect in strength values, quenching process and equal channel angular pressing (ECAP) method stand out among heat treatments and severe plastic deformation methods, respectively. In the current study, quenching and ECAP were applied to low–medium-strength shipbuilding steel and the changes in microstructure and mechanical properties of steel after these methods were comparatively investigated. While martensite was formed in the microstructure after quenching, the average grain size decreased compared to the base material without a phase change with ECAP. Hardness values increased by 100% after quenching and increased by 80% after ECAP. Yield and tensile strength values increased by 3.3 and 2.5 times, respectively, after quenching. On the other hand, yield and tensile strength values after ECAP raised less than after quenching and increased 1.5 and 1.7 times, respectively, compared to the base material. Impact toughness values decreased by 80% after quenching and 10% after ECAP compared to the base material. Also, corrosion resistance of the base material decreased by 13% after quenching and increased by 10% after ECAP. Changes in the mechanical properties of the material after these processes were reflected the middle section of a ship using finite element-based programs and approximately 3.3 times higher than that of the base material for all dimension load–ultimate strength values under uniaxial compression were reached in the model reflecting the mechanical properties of the quenched samples.

Titanium alloys, in particularly Ti-6Al-4V alloy is used enormously in many high-tech sectors specially in aerospace industries due to its superior properties. Machining process (for example wire electrical discharge machining) to reshape this alloy affects the integrity of the newly generated surfaces. This experimental study has identified three affected layers using scanning electron microscopy on the cross section of the machined titanium (Ti-6Al-4V) alloy surface generated from wire electrical discharge machining (WEDM). This study also explained the formation mechanism of those three layers as no detail investigation is available in this area so far. It was found that the top flaky layers are formed due to the highest cooling rate at the outermost surface, which is induced due to the low thermal conductivity of the titanium alloy as well as the quenching effect because of the existence of dielectric. The recast layer is formed at a cooling rate lower than that at the outer surface, where the melted material is resolidified very quickly without having any grain boundaries. The heat-affected zone appears at a slightly different color, which does not melt but experience heat treatment during the machining process.

Impact toughness is affected by chemical composition, defects, microstructure and ambient temperature. Higher impact toughness can prevent premature failure of the bearings. In present work, the microstructure evolution and impact toughness of high-carbon chromium bearing steels with and without rare earth (RE) addition have been investigated after cold rolling, quenching and tempering (QT) treatment. The results show that the addition of RE elements converts irregular MnS, TiN and Al2O3 inclusions with an average size of 9.02 μm into RE inclusions with an average size of 3.76 μm. As a consequence, the impact toughness of specimens with RE is 2.2 times that of without RE. When the cold rolling is applied, since the prior cold rolling can refine the prior austenite grain and increase the residual austenite after QT treatment, the impact toughness also exhibits a significant enhancement from 6.4 to 15.9 J. In addition, for the RE-GCr15 subjected to cold rolling process, the impact toughness can be further increased. This should be attributed to that the refined RE inclusions with good roundness reduce the crack initiation caused by cold rolling, so as to maximize the advantages of cold rolling. The results obtained in this work suggest a good prospect to combine cold rolling process with bearing steel with RE addition.

To solve the problem of difficult utilization of steel slag, the liquid steel slag was modified and the air-quenching granulation process was carried out to make steel slag into a value-added end product: air-quenching granulated steel slag. The granulated slag was tested to analyze the variation rule of slag properties under different modification conditions. Based on the phase diagram of CaO–Si2O–FeO–MgO–Al2O3 slag system, the feasibility of blast furnace (BF) slag as modifier was determined. When the addition of BF slag was increased from 0% to 35%, following results were obtained. The slag fluidity was improved, and the air-quenching temperature range was expanded. Then, the yield of air-quenched steel slag increased, while the granulation rate, the degree of sphericity, the compactness were decreased. Furthermore, the air-quenching granulation process could substantially improve the stability and the amorphous content of steel slag. The maximum removal rate of free CaO was above 80% and the amorphous content was up to 95%. Taking the factors of yield and properties of granulated steel slag into full consideration, the optimum proportion of BF slag is around 15%.

The effect of quenching after martensitic finish (QAMf) or quenching & partitioning (Q&P) on microstructure evolution, mechanical properties, and strain hardening instability of low and medium carbon hot rolled steels were investigated. Two heats of low and medium carbon steels were cast in an induction open furnace. The chemical composition of low carbon steel is 0.16C–0.27Si–1.47Mn–0.02Al while medium carbon steel is 0.49C–0.30Si–0.91Mn–0.03Al. They were hot-rolled at 1200 °C for 30 min followed by air cooling. The microstructure after hot-rolled gives bands of ferrite and pearlite for 0.16 wt% low carbon steel. On the other hand, 0.49 wt% medium carbon steel produces coarse pearlite islands surrounded by ferrite phase. To enhance mechanical properties, it was necessary to modify the microstructure of low and medium carbon steels using QAMf or Q&P processes. The resultant matrix of microstructure after QAMf and Q&P processes contained ferrite, bainite, lath martensite, and retained austenite for 0.16 wt% low carbon steel, and polygonal ferrite, lath martensite, and retained austenite for 0.49 wt% medium carbon steel, respectively. In low carbon steel, QAMf process increased uniform elongation from 6.6 to 13.5% (105% increase) while ultimate tensile strength (UTS) improved slightly from 645 to 692 MPa (7% increase). However, in medium carbon steel, Q&P reduced uniform elongation from 12.4 to 4.8% (61% decrease) while increased UTS from 769 to 1242 MPa (61.5% increase). It is worthy to mention that QAMf process exhibited strain hardening instability zone (7.8% strain before necking) compared to hot-rolled process (0% strain before necking). On the other hand, Q&P process highly decreased strain hardening instability zone (0.77% strain before necking) compared to hot-rolled process (3.4% strain before necking).

To investigate the quenching sensitivity of the 2195 Al–Li alloy rolled sheet and guide the design of the quenching process, the time–temperature-property (TTP) curves of this material were researched through interrupted quenching experiments. The differential scanning calorimetry (DSC) and transmission electron microscope (TEM) were used to characterize the evolution of precipitates during isothermal treatment. The results of this essay demonstrated that the nose temperature of 2195 Al–Li alloy is around 370 °C and the temperature range of quenching sensitivity is 340 °C to 400 °C. The microstructure observation revealed that the T1 particles precipitate and grow rapidly at the temperature from 340 to 400 °C, which is due to the high nucleation rate of phase and fast solute diffusion kinetics, especially at the nose temperature. The needle-shaped θ′/θ″ and T1 particles grow up quickly as the isothermal preservation time prolonged, leading to the decrease of the supersaturated solid solution of the matrix. This will reduce the number of the age-induced precipitate and weaken the subsequent age hardening effect. Therefore, the rate of cooling should be increased in the quenching sensitivity range (340–400 °C) to inhibit the precipitation of the second phase and obtain excellent mechanical properties. While in other temperature ranges, the cooling rate should be decreased appropriately to reduce residual stress. The appropriate average cooling rate is recommended to be around 13 °C s−1 at the temperature from 340 to 400 °C.

Dual-phase (DP) steels mainly consist of ferrite and martensite phases. In this paper, DP steel was developed by inter-critical heat treatment followed by water quenching using AISI 1015 steel whic...

In this paper the results of the investigation of the possibility of strengthening of aluminum alloys with hollow ceramic microspheres and also microspheres modified by pyrolytic chromium coatings, which increase the adhesion between the melt and the microspheres, are presented. Pyrolytic chromium coatings on the microsphere surface were obtained by vapor deposition (metal-organic chemical vapor deposition (MOCVD) method) using organochromium liquid, OCL, commercial name Barkhos. A number of aluminum-matrix composite materials based on the heat-treated by an “artificial aging” AK12ch alloy and heat-treated by “quenching and artificial aging” AK9ch alloy as well as non-heat-treated A6 alloy filled with ceramic microspheres having diameters of 40–80 μm and 100–200 μm have been obtained.

The process of making a weld using the heat-resistant EP693 alloy (Ni–Cr–W–Co–Co–Mo system) to make assemblies and components for gas-turbine engines (GTEs) is considered based on laser welding using a TruLaser Cell 7020 CO2 installation operating in the pulse-periodic radiation mode. EP367 (Ni–Mo–Cr–Mn) additive wire is used to obtain the weld. The effect of thermal treating is studied to estimate the change in structure and properties both in the weld-adjacent area and in the weld. The results are used to examine the structure of the weld and its breaks. The physics and mechanical properties of the weld are evaluated. The greatest durability limit is estimated for welds at a level of 2 × 106 cycles. The feasibility of using a laser-welding heat-resistant dispersion hardened nickel alloy is evaluated to make support and stator shells for GTEs. It is established that complex thermal treatment (quenching and aging) provides for the optimum values of strength at room temperature and at high temperatures. It is also responsible for the short-term strength of welds. According to the strength calculations made for the support and stator of GTE shells and experimental data, the strength of welds made using pulse-periodic laser welding results in a strength safety factor between 1.35 and 3. This technology is proposed for industrial application to make shell parts and assemblies to be used in GTE support and stator in order to improve the quality of welds with a reducing time of high-temperature heating to bring down power consumption.

The process of quenching of a Navy C-ring specimen from steel AISI 4140 is simulated with the help of the DANTE software for determining the effect of stirring of the quenching medium and of the quenching temperature on the distortion of the specimen. The heat transfer coefficients (KT) of the quenching medium at different intensities of its stirring are determined experimentally with the use of a CHTE probe for controlling the heat treatment parameters of metallic materials. The experimental data agree well with the simulation results.

The deformability of brass L63 under equal-channel angular pressing (ECAP) after a preliminary heat treatment (annealing at 600°C or quenching from different temperatures) is studied. The ECAP is conducted at room and elevated temperatures. It is shown that ECAP of brass L63 is possible only at elevated temperatures after preliminary annealing.

The magnetic properties and the changes in the domain structure of alloy Sm(Co, Fe, Cu, Zr)7.5 are studied after different variants of heat treatment, i.e. (1) quenching from 1200°C with cooling in a helium jet; (2) quenching and tempering at 800°C for 16 h, cooling at a rate of 50 K/min to room temperature; and (3) quenching, tempering at 800°C for 16 h, and cooling at a rate of 1.7 K/min. The influence of the heat treatment modes on the coercivity and the domain sizes is determined. The mechanism of variation of these characteristics is analyzed.

The structure and mechanical properties of novel structural high-strength cold-resistant steel 20G2SMRA are studied after quenching and tempering at different temperatures. The heat treatment mode providing combination of guaranteed yield strength σ0.2 ≥ 600 MPa with low-temperature impact toughness KCV–60 ≥ 50 J/cm2 and ductility δ5 ≥ 17% is suggested. The results of the study are to be used in commercial production as applied to mill “5000” of the “MMK” Company.

This article analyzes the influence of high-speed melt quenching by extracting a suspended melt droplet of a Ta–Zr binary system. Two mixtures of powdered tantalum and zirconium are used with a tantalum content of 60 and 6%, respectively. The compositions after mixing were pressed under a pressure of 250 MPa in a steel mold on a hydraulic press. Sintering is carried out in a vacuum furnace at 1350°C and 10–3 Pa. High-speed quenching is carried out in vacuum under a pressure of 2 × 10–2 Pa by electron-beam heating and a rotating disk heat receiver. The thickness of the produced fibers is 15–80 μm. The experimental results of discrete fibers of Ta–Zr alloy and samples obtained by the fusing of the billet by electric beam hating (in an as-cast state) are analyzed and compared. It is established that the structure of rapidly quenched fibers of the alloy with 6 wt % Ta is comprised of grains of acicular shape with a size of 5–10 μm and the fibers with 60 wt % Ta have columnar dendrite structure. An analysis of the distribution of tantalum and zirconium across the transversal cross section of fiber demonstrates that, with a decrease in the cooling rate below 105 K/s in the alloy with a tantalum content of 60 wt %, monotectoid transformation occurs. It is revealed that the microhardness of rapidly quenched fiber of the alloy with 6 wt % Ta is 1.5 times higher than that of the same alloy without quenching, and for the alloy with 60 wt % Ta the same comparison demonstrates double dominance.