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The unconventional machining processes are popular in machining the difficult to cut type complex contour/ profile. The key parameters are to be machined with care as they directly affects the function and non key dimensions are machined with other than consideration of functional aspect, like design, passage. That means accuracy is less important in those dimensions but finish is to be good. So the machining of engineering materials does not always require optimizing parameters based on multiple responses. This investigation focuses on the sensitiveness of Wire EDM of 12X18H10T - Stainless Steel and identifying the parameters contribution and establish mathematical model to predict values without trial. An austenitic alloy 12X18H10T - Stainless Steel exhibits its inherent mechanical properties even when it expose to extremely high temperature. Ithas potential application in aerospace engine components manufacturing. This investigation utilized the Taguchi L9 experiential Design with factors of Pulse off Time, Wire Tension, Pulse on Time, and Wire Feed Rate. This study aims to examine Maximize the rate of machining with Taguchi approach in the process of Wire EDM of 12X18H10T - Stainless Steel and establish a mathematical model to predict the highly influencing parameter(s) for desired rate of machining.

The effect of aging time and temperature variants on the Ni-Ti Shape Memory Alloy (SMA) has been investigated in this study. After the aging process, microstructural characterization was carried out using Scanning Electron Microscope (SEM) and X-Ray Diffraction (XRD) data. Using an innovative technique, Austenite finish (Af) temperature was determined. Aging effects on the hardness of the material were studied using Vickers Microhardness Test. SEM results revealed uniform distribution of α-Ni and β-Ti phases, appearance and disappearance of martensite plates and presence of precipitates. XRD analysis of the samples indicated that etching resulted in formation of oxides. The Af temperature was observed to increase with increase in aging temperature. In the Vickers Microhardness Test, it was seen that the mid-range time variant samples showed lower HV values.

The frequent replacement of worn rails on tracks brings an immense economic burden on the railroad industry, and also causes significant interruptions to railroad operation. Restoration of worn rails via laser powder deposition (LPD) can considerably reduce the associated maintenance costs. This study was focused on the use of LPD to repair the worn profile of a standard U.S. rail. The microstructure of the 304L stainless steel deposits with a minimum hardness of 85 HRB was composed of austenite, δ-ferrite, and sigma. Micropores were dispersed throughout the deposit, and microcracks were found at the rail-deposition interface. The pearlitic rail substrate showed a moderate hardness of 94 HRB. The fine-grain, pearlitic-ferritic heat affected zone had the maximum hardness of 96 HRB, which was still below the minimum required hardness of 97 HRB for a typical rail. To increase the hardness to or above 97 HRB and to mitigate the microstructural defects, the as-repaired rail went through a heat treatment process. The average hardness of the as-treated rail was increased significantly, i.e., to 103 HRB. Besides, the porous and coarse-grain deposition materials were transformed into an impermeable and fine-grain microstructure. However, heat treatment intensified the microcracks at the rail-deposition interface and also led to the formation of martensite and augmentation of the micropores in the parent rail. Isolation of the base rail during heat treatment and preheating were suggested as solutions for the problematic results. The LPD process ultimately was found to be a promising technique for repairing rails.

Advanced bainitic steels with the multiphase structure of bainitic ferrite, retained austenite and martensite exhibit distinctive fatigue crack initiation behavior during high cycle fatigue/very high cycle fatigue (HCF/VHCF) regimes. The subsurface microstructural fatigue crack initiation, referred to as “non-inclusion induced crack initiation, NIICI”, is a leading mode of failure of bainitic steels within the HCF/VHCF regimes. In this regard, there is currently a missing gap in the knowledge with respect to the cyclic response of multiphase structure during VHCF failure and the underlying mechanisms of fatigue crack initiation during VHCF. To address this aspect, we have developed a novel approach that explicitly identifies the knowledge gap through an examination of subsurface crack initiation and interaction with the local microstructure. This was accomplished by uniquely combining electron microscopy, three-dimensional confocal microscopy, focused ion beam, and transmission Kikuchi diffraction. Interestingly, the study indicated that there are multiple micro-mechanisms responsible for the NIICI failure of bainitic steels, including two scenarios of transgranular-crack-assisted NIICI and two scenarios of intergranular-crack-assisted NIICI, which resulted in the different distribution of fine grains in the crack initiation area. The fine grains were formed through fragmentation of bainitic ferrite lath caused by localized plastic deformation or via local continuous dynamic recrystallization because of repeated interaction between slip bands and prior austenite grain boundaries. The formation of fine grains assisted the advancement of small cracks. Another important aspect discussed is the role of retained austenite (RA) during cyclic loading, on crack initiation and propagation in terms of the morphology, distribution and stability of RA, which determined the development of localized cyclic plastic deformation in multiphase structure.

We systematically compared the mechanical properties of CrCoNi, a recently emerged prototypical medium-entropy alloy (MEA) with face-centered-cubic (FCC) structure, with hallmark FCC alloys, in particular, the well-known austenitic 316L and 316LN stainless steels, which are also concentrated single-phase FCC solid solutions and arguably next-of-kin to the MEAs. The tensile and impact properties, across the temperatures range from 373 K to 4.2 K, as well as fracture toughness at 298 K and 77 K, were documented. From room temperature to cryogenic temperature, all three alloys exhibited similarly good mechanical properties; CrCoNi increased its tensile uniform elongation and fracture toughness, which was different from the decreasing trend of the 316L and 316LN. On the other hand, the stainless steels showed higher fracture toughness than CrCoNi at all temperatures. To explain the differences in macroscopic mechanical properties of the three alloys, microstructural hardening mechanisms were surveyed. CrCoNi MEA relied on abundant mechanical twinning on the nanoscale, while martensitic transformation was dominant in 316L at low temperatures. The deformation mechanisms in the plastic zone ahead of the propagating crack in impact and fracture toughness tests were also analyzed and compared for the three alloys.

Increasing the yield strength of austenitic steel without significantly sacrificing ductility has been a long-standing technical challenge. Here, we obtained an ultrahigh yield strength (∼1.4 GPa) and ductile (∼37% uniform elongation) austenitic steel through innovatively combining cold rolling, flash annealing, and tempering (CFT) processes. Such CFT steel shows a heterogeneous lamellar microstructure composed of reversed austenite and partially recrystallized austenite. The ultrahigh yield strength is attributed to the synergistic strengthening mechanisms induced by high-density dislocations, nano/ultrafine grains, and nanoscale precipitates. The achieved high ductility is associated with the pronounced transformation-induced plasticity (TRIP) effect induced by the high-density dislocations combined with the twinning-induced plasticity (TWIP) effect induced by grain refinement. Such a strengthening and plasticity mechanism paves the way for a processing route to achieve ultrahigh strength-high ductility combination in austenitic steel.

Control of the formation and stability of reverted austenite is critical in achieving a favorable combination of strength, ductility, and toughness in high-strength steels. In this work, the effects of Cu precipitation on the austenite reversion and mechanical properties of maraging stainless steels were investigated by atom probe tomography, transmission electron microscopy, and mechanical tests. Our results indicate that Cu accelerates the austenite reversion kinetics in two manners: first, Cu, as an austenite stabilizer, increases the equilibrium austenite fraction and hence enhances the chemical driving force for the austenite formation, and second, Cu-rich nanoprecipitates promote the austenite reversion by serving as heterogeneous nucleation sites and providing Ni-enriched chemical conditions through interfacial segregation. In addition, the Cu precipitation hardening compensates the strength drop induced by the formation of soft reverted austenite. During tensile deformation, the metastable reverted austenite transforms to martensite, which substantially improves the ductility and toughness through a transformation-induced plasticity (TRIP) effect. The Cu-added maraging stainless steel exhibits a superior combination of a yield strength of ∼1.3 GPa, an elongation of ∼15%, and an impact toughness of ∼58 J.

Laser engineered net shaping (LENS) is an advanced additive manufacturing technology combining rapid prototyping and synchronization technology. Its multi-powder feeder delivery system enables multi-materials building in single deposition, which is appropriate for additive manufacturing of functionally graded materials (FGMs). In this study, martensitic-stainless steel (MSS)/austenitic stainless steel (ASS) FGMs with composition transitioning from 100% MSS incrementally graded to 100% ASS by 25% composition gradients are fabricated by LENS. The Vickers hardness of MSS/ASS FGMs ranges from 358 to 170 HV. The decrease of hardness is found to relate to the grain-growth region with the increase of austenite. The obtained specimens of MSS/ASS FGMs show a tensile strength of 669 MPa and an elongation of 19%. In addition, the fracture location of MSS/ASS FGMs in tensile test is in the region of 100% ASS, which is dominated by austenite structure. Finally, the Scheil–Gulliver model is introduced to validate the phase formation of MSS/ASS FGMs’ failure region. Experimental and modeling results indicate that precipitation of α-ferrite in the austenite structure leads to reduced ductility of MSS/ASS FGMs.

Austenitic stainless steels (AISI 304) is most versatile grade in stainless steel and widely used in various industries owing to its attractive properties. It has high durability, high ductility, toughness at cryogenic temperature and excellent resistance against corrosion. In addition, this steel has excellent weldability, high resistance against fatigue and oxidation. However, owing to their high work hardening, high built up edge and low heat conductivity, AISI 304 stainless steel is considered as most difficult to-cut material than other alloy steels. To overcome this, various cutting fluids are used to enhance the life of cutting tools, reduce cutting temperature, reduce friction between tool and workpiece, and to improve the machining efficiency and surface integrity. Thus, the aim of this review paper is to summarize the various investigations done by distinct researchers on machining performance of AISI-304 stainless steel. In addition, various applications and factor that affect the performance of AISI-304 stainless steel are also discussed, so that this paper could become useful for the futuristic researchers to select optimum machining parameters, coolant type and machine for improving the overallmachined surface integrity.

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.

Selective laser melting (SLM) is an additive manufacturing process in which layers of metallic powder are selectively melted and fused by a high-powered laser to form near-fully dense 3D components. The SS316L is an austenitic chromium-nickel stainless steel containing a deliberate amount of molybdenum which increases general corrosion resistance and especially improves its pitting resistance to chloride ion solutions. The importance of process parameter such as layer thickness and orientation of specimen on the hardness and microstructure are being explored. Hence, it is essential to carry out research in that direction. The aim of the study is to understand the effect of layer thickness and angle orientation on hardness of the material as it is one of the desirable properties for SS316 material. The excellent hardness (218.835 BHN) was attained at the angle orientation of 90° and layer thickness of 40 µm according to ANOVA analysis.

Ultrafast heating (UFH) at the rates of 10–300 °C/s was employed as a new strategy to anneal a cold-rolled 7wt% Mn steel, followed by the immediate cooling. Severely deformed strain-induced martensite and lightly-deformed thermal martensite, both had been already enriched with C and Mn before, transformed to fine and coarse austenite grains during the UFH, leading to the bimodal size distribution. Compared with the long intercritical annealing (IA) process, the UFH processes produced larger fraction of RA grains (up to 37%) with a high density of dislocation, leading to the significant increase in yield strength by 270 MPa and the product of strength and elongation up to 55 GPa% due to the enormous work hardening capacity. Such a significant strengthening is first attributed to high density dislocations preserved after UFH and then to the microstructural refinement and the precipitation strengthening; whilst the sustainable work hardening is attributed to the successive TRIP effect during deformation, resulting from the large fraction of RA instantly formed with the bimodal size distribution during UFH. Moreover, the results on the microstructural characterization, thermodynamics calculation on the reverse transformation temperature and the kinetic simulations on the reverse transformation all suggest that the austenitization during UFH is displacive and involves the diffusion and partition of C. Therefore, we propose that it is a bainite-like transformation.

Several components fabricated from 25Cr7Ni stainless steel are widely used in industry owing to its beneficial combination of high strength and superior corrosion resistance. There are very few studies reported in the literature on the laser-powder bed fusion (L-PBF) fabricated properties of 25Cr7Ni stainless steel. The current study is focused on understanding the effect of powder attributes and chemical composition on the properties of L-PBF processed 25Cr7Ni stainless steel. L-PBF fabricated samples made from gas and water atomized 25Cr7Ni powders were evaluated in the present study for densification, mechanical and corrosion properties. The L-PBF samples processed from gas atomized powders displayed higher densification, tensile strength and superior corrosion resistance compared to samples made from water atomized powders. The superior corrosion resistance of L-PBF samples made from gas atomized powders is attributed to the presence of austenite phase in microstructure. The corrosion resistance of L-PBF gas atomized powder samples were comparable to the wrought-annealed 25Cr7Ni stainless steel.

High entropy alloy (HEA) with shape memory effect (SME) has been the subject of great interest for the past few decades. However, with the increased demands for new materials for high thermal applications, the research activities on the multi elemental high entropy shape memory alloys (HESMA) have been increased by many folds recently. The nano crystalline HEA powder with shape memory effect developed in this study, HfZrTiFeMnSi, was produced by mechanical alloying (MA) for the first time. In this method equiatomic ratio of Hf, Zr, Ti, Fe, Mn, and Si were mixed together and milled by MA process for 100 h. The powder formed was of amorphous in nature. Elemental mapping of the powder from SEM-EDS revealed homogeneity of the alloying elements confirming successful fabrication of HfZrTiFeMnSi HEA powder. The DSC studies from ambient to 500 °C of the annealed alloy powders showed reversible austenitic to martensitic (A↔M) transformations. The A↔M transformation hysteresis seemed to vary with the milling time and annealing temperature. The enthalpy values, ΔH, for the transformation were calculated from the DSC plots using tangent method for peak area calculation. Regardless of the annealing temperature, the thermal analysis revealed that the ΔH, equilibrium temperature (T0), and crystallization temperature values decreased with the increasing milling time.

While Fe–Ni–Cr austenitic stainless steels exhibit relatively good resistance to hydrogen embrittlement, they still suffer from significant degradation of ductility, fatigue and fracture properties in gaseous hydrogen environments. Experimental studies in the literature suggest that hydrogen reduces stacking fault energy in austenitic stainless steels. This phenomenon causes a large separation of partial dislocations and lower propensity for cross-slip. Whereas lower stacking fault energy does not correlate well with loss of ductility in the absence of hydrogen, lower stacking fault energy trends toward greater loss of ductility when hydrogen is present. Calculations of stacking fault energy are challenging for austenitic stainless steels. One main issue is that in alloys, stacking fault energy is not a single value but rather varies depending on local composition. Herein, we first report an Fe–Ni–Cr–H quaternary interatomic potential and then use this potential to perform time-averaged molecular dynamics simulations to calculate stacking fault energies for tens of thousands of realizations of local compositions for selected stainless steels alloys with and without internal hydrogen. From statistical analyses, our results suggest that hydrogen reduces stacking fault energy, which likely impacts deformation mechanisms of Fe–Ni–Cr austenitic stainless steels when exposed to hydrogen environments. We then perform validation MD simulation tests to show that hydrogen indeed statistically increases the stacking fault widths due to statistically reduced stacking fault energies.

The corrosion of unaged and 7000-h thermally aged 308L stainless steel weld metals in simulated PWR primary water under aerated and deaerated conditions was investigated, involving the corrosion of austenite, δ-ferrite and δ-ferrite/austenite phase boundary. The results revealed that thermal ageing for 7000 h had a limited effect on the corrosion behavior of 308L weld metal as it only increased the inner oxide thickness of δ-ferrite slightly under the deaerated condition. No obvious corrosion enhancement of 308L weld metal under the aerated condition was found compared to the deaerated condition regardless of the thermal ageing. Nevertheless, Cr-enrichment on the surface of oxide particles, dissolved regions at the metal/oxide interface and localized corrosion along the δ-ferrite/austenite phase boundary occurred under the aerated condition.

Duplex stainless steels (DSSs) are promising materials in many fields due to their excellent corrosion resistance and mechanical properties, which are resulted from their microstructure consisted of a roughly equal amount of austenite and ferrite phases. As a revolutionary production technology, additive manufacturing (AM) has exhibited tremendous advantages for the fabrication of metal parts of complicated or customized geometry. Wire arc additive manufacturing (WAAM), laser metal deposition (LMD) and laser powder bed fusion (L-PBF) have been utilized to fabricate DSSs. However, it is of a great challenge to achieve expected formation quality and microstructure at the same time, considering the complicated layer-upon-layer process. A delicate control of processing conditions is highly required based on the understanding of DSS materials and AM processes. In this work, an overview of the up-to-date research status and future perspectives on the AM of DSSs is presented from extensive viewpoints including materials, processing, microstructure and properties. The microstructure evolution during the AM processes is highlighted in detail, which explains the change of mechanical properties and corrosion resistance, and provides the direction of processing optimization.

For tensile tests, Vickers hardness tests and microstructure tests, plate-type and box-type specimens of austenitic 316L stainless steels were produced by a conventional machining (CM) process as well as two additive manufacturing processes such as direct metal laser sintering (DMLS) and direct metal tooling (DMT). The specimens were irradiated up to a fast neutron fluence of 3.3 × 109 n/cm2 at a neutron irradiation facility. Mechanical performance of the unirradiated and irradiated specimens were investigated at room temperature and 300 °C, respectively. The tensile strengths of the DMLS, DMT and CM 316L specimens are in descending order but the elongations are in reverse order, regardless of irradiation and temperature. The ratio of Vickers hardness to ultimate tensile strength was derived to be between 3.21 and 4.01. The additive manufacturing processes exhibit suitable mechanical performance, comparing the tensile strengths and elongations of the conventional machining process.

The present work deals with the effect of B, V, Ti on the microstructural evolution and mechanical behavior of high chromium white cast iron. The comparison is also made with Ni-hard iron in as-cast condition. The destabilization treatment provided after casting resulted in decomposition of austenite into martensite and secondary carbides and further tempering treatment resulted in decomposition of martensite into ferrite and secondary carbide phases. Phase analysis by x-ray diffraction revealed two main phases, i.e., a BCC-Fe matrix and a primary carbide phase. In addition to this, high chromium white cast iron and Ni-hard alloys contain austenitic phase (FCC-Fe) (Fig. 2(a)). The primary carbides are M7C3 for V additions whereas for all other cases, they are M3C2. Ti and B additions led to the formation of secondary carbides of M7C3 and M23C6, respectively. Effect of alloying elements on phases formed and further modification of the microstructure are discussed in detail. The hardness of unalloyed high chromium white cast iron is highest amongst all the alloys tested, however, Ti and V additions to it retained this hardness to almost the same extent. V addition to the alloy showed not only highest tensile strength but also longer elongation to fracture, thereby, resulting as toughest alloy in the lot. On the other hand, Ni-Hard iron showed the least tensile strength and elongation before fracture. This study, thereby concludes that high chromium white cast iron with V additions is suitable for manufacture of coal pulveriser grinding media owing to its higher hardness and toughness.

The residual stresses (RS) contribute to the integrity of the welded joint. In some cases, such as repaired dissimilar joints, this factor is crucial. The longitudinal (hoop) and transverse residual stresses of three chromium-molybdenum steel (A387 Grade 11)/austenitic steel (AISI 304) dissimilar welded repair mockups were measured in this study. The first and second repair mockups used ENiCrMo-3 and ENiCrFe-3 (conventional procedures), while the third repair mockup used ENi-1 as a buffer layer plus ENiCrFe-3. The contour method was used to measure longitudinal RS, and the slitting method was used to measure transverse RS. The buffer layer procedure resulted in lower longitudinal stresses at the interior regions of the repair than the other two procedures. The first, second, and third mockups showed transverse RS lower than the yield strength of the corresponding metals, with peak tensile stresses of 279, 113, and 230 MPa, respectively.

The roles of pre-formed martensite (PM) in below-Ms bainite formation, microstructure, crystallography, strain partitioning and mechanical properties of a low-carbon bainitic steel were investigated using electron-backscattered diffraction, transmission electron microscopy, micro digital image correlation technique and mechanical tests. It is demonstrated that the pre-formation of martensite eliminates the incubation time for bainite transformation at various austempering temperatures below Ms, indicative of its acceleration effect at the early stage of transformation. This effect is mainly attributed to the surfaces or tips of the PM acting as the nuclei of subsequently-formed bainite, with initial bainite tending to form around the PM. However, the finishing time for below-Ms bainite transformation, especially at even lower temperatures, is retarded, owing to the dividing effect of PM on parent austenite grains, the decreasing effect of lowered isothermal temperature on the diffusion rate of carbon atoms and the strengthening effect of lowered isothermal temperature on supercooled austenite. PM and its adjacent bainitic laths have nearly the same crystallographic orientation and belong to the same block. The pre-formation of martensite largely refines the bainitic blocks/laths and retained austenite. The specimens with PM show relatively uniform strain partitioning among various phases, contrasting with the specimens without PM, for which strains are highly concentrated in the bainite region nearby fresh martensite/austenite (M/A) blocks or between adjacent M/A blocks. The impact absorption energies of the specimens with PM, when austempered at 30–60 °C below Ms, are more than twice higher than those of the specimens without PM, at no expense of tensile properties.

Duplex stainless steel (DSS) with an austenite-ferrite duplex microstructure offers high strength and toughness, excellent resistance to intergranular and chloride corrosion, and good weldability. The strain hardening behavior of austenite and ferrite phases in duplex stainless steel, when subjected to a tensile stress condition, is studied in the current work. Specimens were prepared from test blocks soaked at a temperature of 1160˚ C followed by furnace cooling to 1060 ˚C and water quenching. Heat-treated samples were deformed for varied percentage elongations. Microstructural analysis using optical microscopy revealed the deformations in austenite and ferrite phases. The concentrations of component alloying elements were determined using Energy Dispersive X-Ray Analysis (EDX) and area-scan techniques. At each level of percentage deformations, as well as on the fractured sample, microhardness measurements were taken on both austenite and ferrite phases. The hardness values of both austenite and ferrite phases were observed to rise continuously with an increase in deformation. The rise in hardness value of the ferrite phase was found to be significantly higher than the rise of hardness in the austenite phase, proving that the ferrite phase has a higher work hardening with deformation.

Cast austenitic stainless steel grade CF8C of ASTM A351 possesses varying degrees of suitability for services both at high temperatures and in corrosive environments. CF8C contain Nb of 1% max as per ASTM A351, i.e. 8 times the carbon content. Unlike CF8M and CF3M of ASTM A351, CF8C grade has option for stabilization treatment due to Nb present which forms carbides, between 870 and 900 °C after solution annealing in austenite matrix. This prevents depletion of chromium around grain boundary and prevents sensitization of steel. However, this stabilization treatment has been mentioned as supplementary requirement of ASTM A351 Clause 3.1 depending on the end property requirement. In this line, experimentation carried out on solution annealing and solution annealing + stabilization treatment of CF8C grade and testing carried out in order to evaluate properties after both treatments. For other stainless steels like CF8M, and CF3M of ASTM A351 similar experiment carried out.

A two-fold approach is considered to study hydrogen (H) diffusion characteristics in martensitic steels. Initially, a multi-trap stress coupled H diffusion finite element model was developed to investigate the role of various trap states on effective H trapping during a four point bend test. The calculations show that high angle boundaries are more influential in controlling H diffusion in presence of low initial (bulk) H concentrations, while dislocations can have more pronounced impact, when the bulk H concentration is higher. A microstructural model comprising of prior austenite grains and packets was further developed. The study highlights the importance of packet boundaries (PBs) moderating H diffusion in martensite microstructure. The presence of retained austenite content affecting H diffusion paths was also studied. Overall, this parametric study presents complementary techniques in numerical modeling, as well as implications on the role of various microstructural entities affecting H diffusion.

The combination of Ni3Al-based superalloy and S31042 steel could meet service requirement of different parts in nuclear power units. To broaden the application of Ni3Al-based alloy, vacuum diffusion bonding with S31042 austenitic heat-resistant steel was studied in this work. Different thicknesses (2, 5, 10, 15, 30 μm) of pure Ni interlayer were adopted to obtain a sound bonded joint. Result shows that the formed AlN phase in bonding process hindered atom diffusion and deteriorated joint properties. When interlayer thickness is 15 μm, the joint strength reached 96% of Ni3Al-based alloy, meanwhile elongation was 320% of Ni3Al-based alloy and 62% of S31042 alloy. The less AlN phase, uniform precipitation of γ′ phase and grain boundary intermigration behavior in two substrates contribute to the high strength and elongation of joint. The prevailing mechanism of the dissimilar joint bonded by 15 μm interlayer is ductile fracture. However, the fracture with low elongation showed the equiaxial pot and intergranular torn edges in other bonded samples due to the typical dual-phase structure in interlayer.

High-strength pipeline steel was subjected to friction stir welding (FSW) at rotation rates of 400–700 rpm, and the grain refinement mechanism of the nugget zone (NZ) was determined. The thermo-mechanical process during FSW in the NZ was simulated by multi-pass thermal compression, thereby achieving the austenitic non-recrystallization temperature (Tnr). The austenitic non-recrystallization in the NZ at the lowest rotation rate of 400 rpm caused a significant grain refinement. Furthermore, the reduced rotation rate also resulted in the formation of a high ratio of island-like martensite-austenite (M-A) constituent. The toughness of the NZs was enhanced as the rotation rate decreased, which is attributed to the fine effective grains and homogeneously distributed fine M-A constituents dramatically inhibiting crack initiation and propagation.

This study aims to compare the design, metallurgy, microhardness, and mechanical properties of 3 glide path nickel-titanium (NiTi) instruments.A total of 132 ProGlider (Dentsply Sirona, Ballaigues, Switzerland), Edge Glide Path (EdgeEndo, Johnson City, TN), and R-Pilot instruments (VDW, Munich, Germany) (44 per group) were selected. Design was assessed through stereomicroscopy (blades, helical angle, measuring lines, and deformation) and scanning electron microscopy (symmetry, cross section, tip, and surface finishing). NiTi ratios were measured by energy-dispersive X-ray spectroscopy and phase transformation temperatures by differential scanning calorimetry. Microhardness and mechanical performance (torsion, bending, and buckling resistance tests) were also evaluated. Statistical analyses were performed with the Mood median test with a significance set at 5%.The Edge Glide Path had the lowest number of blades and the R-Pilot the greatest helical angle. All instruments had an almost equiatomic NiTi ratio, while showing different cross sections and tip geometries. The Edge Glide Path had a smoother surface finishing. The R-Pilot showed martensitic characteristics at room temperature, whereas mixed austenite plus R-phase was observed in the other instruments. The R-Pilot had higher results on the microhardness (436.8 hardness Vickers number), maximum torsion (0.9 Ncm), and buckling load (0.7 N) tests (P .05), whereas the Edge Glide Path had a superior angle of rotation (683.5°) and the ProGlider was more flexible (144.1 gf) (P .05).Differences in the design of the instruments and the phase transformation temperatures accounted for their mechanical behavior. The R-Pilot showed the highest torque, buckling, and microhardness, whereas the ProGlider instrument was the most flexible.

This paper presents a finite element analysis of cold-formed stainless steel channels with circular web holes, subjected to end-one-flange loading condition. The material properties of stainless steel types EN 1.4509 (Ferritic), EN 1.4462 (Duplex) and EN 1.4301 (Austenitic) were taken from the literature. To investigate the effect of web hole size, web hole location and bearing length on the web crippling strength of such sections, a parametric study involving a total of 1728 FE models was performed. The parametric study results were used to propose new web crippling strength equations and strength reduction factor equations which outperformed the equations of American Society of Civil Engineers Specification (ASCE 8–02), American Iron and Steel Institute Specification and Australia/New Zealand Standard (AISI&AS/NZS) and Lian et al (2016). A reliability analysis was then performed, which showed that the proposed design equations can closely predict the web crippling strength of cold-formed stainless steel channels with and without web holes under end-one-flange loading condition.

Complex precipitation behavior of Cu-rich particles (CRPs) was investigated and simulated in continuously cooled and quench-aged super duplex stainless steel. Atom probe tomography (APT) and scanning electron microscopy showed that slow cooling resulted in nonuniform multimodal CRP precipitation and spinodal decomposition, while in the fast cooled and quench-aged conditions, more uniform precipitation of CRPs with no visible spinodal decomposition was found. Depletion of Cu, Ni, and Mn was observed in the ferrite next to the CRPs during growth, but not during dissolution. Some evidence of Ostwald ripening was seen after slow cooling, but in the quench-aged condition, particle coalescence was observed. Large CRPs disappeared next to a ferrite–austenite phase boundary after slow cooling when Cu was depleted due to the diffusion to austenite as also predicted by moving boundary Dictra simulation. Comparing Cu depleted areas next to CRPs analyzed by APT and moving boundary Dictra simulation of CRP–ferrite showed that the effective Cu diffusion coefficient during the early-stage precipitation was about 300 times higher than the Cu diffusion coefficient in ferrite at 475 °C. Using the effective diffusion coefficient and a size-dependent interfacial energy equation, CRP size distribution was successfully predicted by the Langer–Schwartz model implemented in Thermo-Calc Prisma. Applying a short aging time and continuous cooling increased the hardness and decreased the toughness values compared to the solution annealed condition. A nonuniform distribution of Cu in ferrite, the duplex structure, and partitioning of alloying elements among different phases are factors making CRP precipitation in duplex stainless steels complex.

Due to its high strength and wear resistance and good fracture toughness at low and high temperatures, AISI H13 tool steel has been widely used to fabricate components such as injection molds, die casting dies, and hot forging tools. Components with complex geometries can be produced by additive manufacturing (AM); however, the success of this manufacture depends on the formed microstructure and mechanical properties, which are associated with the process parameters. The mechanical properties of H13 tool steel processed by AM reported in the literature are limited to those obtained through hardness and tensile tests. Thus, this study aims to correlate the bending properties of H13 tool steel with its microstructure and process parameters when processed by the Powder Bed Fusion (PBF) technique. The samples were produced with different energy densities (approximately 200, 400, and 600 J/mm³) and analyzed by XRD, OM, SEM, and ACOM-TEM. The amount of retained austenite in the cellular microstructure and the porosity decreased as the energy density increased. The sample manufactured with 400 J/mm³ presented the highest density and bending stress values. In contrast, the sample produced with 600 J/mm³ showed a smaller number of defects and more extensive deformation before fracture. This behavior was explained considering the fraction of retained austenite, intrinsic tempering, and presence of defects. The fracture mechanism comprised a mixture of cleavage and dimple formation. This study demonstrates that the bending properties of H13 tool steel processed by PBF are directly related to the resulting microstructure and process parameters used to fabricate the parts.

A nickel-free high nitrogen duplex stainless steel holding high Mn-content was friction stir spot welded under the various rotational speeds. The microstructure/texture evolutions of the joints and the correlated mechanical properties were investigated in detail. The ferrite and austenite constituent massive phases were refined down to the mean grain size of 0.9 μm and 1.1 μm, respectively. The microstructure evolutions revealed the activation of continuous dynamic recrystallization as the main restoration mechanism. This was further verified through the formation of Β- and Α-fiber shear texture in the specimens processed under the various processing condition. Besides the activation of different restoration micro-mechanisms in both ferrite and austenite, dynamic phase transformation of ferrite to austenite was also contributed in grain refinement. The transformation was facilitated by providing more diffusional paths through substructure development and grain refinement. The local and bulk mechanical properties of the joints were also assessed. The outstanding tensile-shear peak load of 12.8 KN obtained for the sample welded at 400 rpm was discussed relying on the developed ultrafine-grained microstructure and the maximum peak extension of 1.7 mm achieved at 600 rpm was attributed to the role of ferrite phase in strain accommodation.

Solution treatment process is stepwise process in manufacturing of iron based shape memory alloy. It is well known that the grain size of austenite in the solution treatment condition depends on the austenitizing/solutionizing temperature. Moreover, the solution treatment temperature influences the transformation temperatures of SMAs. It has been found by researchers that solution treatment temperature brings about modification in the grain size, the grain boundary angles, and the annealing twins. The major objective of the present work is therefore to assess the influence of modifications in the microstructural features by using different solution treatment temperatures. Optical microscopic studies reveal the microstructural changes brought about by changing the solution treatment temperature. DSC shows that somewhat change of transformation temperatures in regarding to the conjugated solution treatment temperature, but the martensite transformation temperatures are still in the range of ambient temperature. X-ray diffraction results refer to the enhancement of SIEM in the alloy that was solution treated at 1000 °C. TEM observations prove that uniform stacking faults have been generated at the austenite of the alloy that has been solution treated at 1000 °C. In addition, SADP shows that e-martensite is the domain structure generated after 3.1% pre-strain of the sample that has been solution treated at 1000 °C. The results indicate that solution treatment at an optimal temperature of 1000 °C leads to increase of shape memory effect of iron base shape memory alloy.

The heterogeneous trans-scale structures play important roles in achieving high strength and toughness in austenitic stainless steels fabricated by directed energy deposition (DED). In this study, systematic annealing investigations were demonstrated the evolution of trans-scale heterogeneous structures such as dislocations, chemical cells, nano-oxides, grains and recrystallization behavior. Their effects on yield strength were quantified. The experimentally observed yield strength of as-received and annealed samples agrees well with the estimated yield strength using standard Taylor hardening formulae. The dislocation intensity accounted for 200 MPa and became the main strength contributor, among which GND type of dislocation accounted for more than 60% of the total dislocation. Despite the development of DED steel micro inclusions, the synergistic effect of deformation twinning and pre-existing GND-induced back stress results in high tensile plasticity. This research helps to better understand the interplay between DED processing, the microstructure of 316L stainless steel and the mechanical properties that are crucial to meeting new demands.

This work highlights a new process for direct manufacturing of ductile iron that is based on the innovative combined technology of quenching and partitioning, and low-temperature-transformation of nano bainite as used for high strength steels. In this process, a commercial unalloyed ductile iron is austenitized at 890 °C for 20 min, then rapidly quenched to 180 °C for 5 s, and finally partitioned at 220 °C for 240 min. A maximum tensile strength of more than 1600 MPa, a hardness of 55 HRC at an elongation in excess of 5%, and the number of repeat tensile fatigue failure of 2.5 × 104 cycles at a stress amplitude of 600 MPa, are achieved. This is comparable to those of a high strength carbon alloy steel. These properties are due to the synergistic strengthening and toughening effects of a multiphase structure comprising tempered martensite, bainitic ferrite and retained austenite in the matrix, and a spherical graphite morphology. This work provides a guidance on how to produce unique steel-like ductile iron with a high level of strength and acceptable toughness.

The competition mechanism of ferritic recrystallization and austenitic transformation, nucleation and growth kinetics of different crystallographic orientation components during intercritical annealing of a cold-rolling Fe-Al-Mn-Mo-C deep drawing dual-phase steel were investigated by a series of continuous annealing simulation experiments. The experiments provided an insight into the microstructural characteristics and mechanical behaviors that were caused from the interaction of primary recrystallization and phase transformation. The results show that the promoting effect of austenite transformation is greater than that of ferrite recrystallization with the increase of temperature in the two-phase region, and an appropriate soaking time is contributed to the formation and development of {111} oriented grains. Austenite formation affects morphology and size of the microstructure owing to inhibiting ferrite recrystallization and growth. From these that experimental data of the observed temperature or time-dependent mechanical properties can be interpreted. An excellent comprehensive properties with tensile strength of 480 MPa and plastic strain ratio (r value) of 1.15 can be obtained at annealing temperature of 880 oC for 300 s.

The microstructure evolution and microhardness of Q&P980 steel heat-affected zone (HAZ) was investigated systematically using weld thermal simulation technique. The phase transformation temperatures were determined by the dilatometry. Ac1 and Ac3 were observed to be quite constant, 750 and 935 °C, at the heating rates higher than 150 °C/s. The different regions of HAZ were obtained varying the peak heating temperature in the simulation experiments. With the peak temperature increased from 300 to 1350 °C, the microstructure evolved from martensite/ferrite/retained austenite to tempered martensite/carbides/ferrite, then finally turned to single martensite phase with fine lath or coarse lath morphology. The volume percentage of retained austenite reduced dramatically from 13% to 2% due to retained austenite transformation at high temperature. The lowest microhardness of 268 HV was obtained in sub-critical HAZ and the highest microhardness of 485 HV was obtained in fine grained HAZ. The welding continuous cooling transformation (CCT) diagram of Q&P980 steel corresponding coarse grained HAZ was constructed by dilatometric methods. There was ferrite, bainite and martensite transformation regions when the cooling rates ranged from 0.1 to 100 °C/s. The microhardness kept at a high certain level of 450-460 HV at high cooling rates (≥20 °C/s) because of the formation of martensite. By the CCT diagram determined, the effect of cooling rate on microstructure and microhardness can be deduced and utilized for optimizing the welding parameters.

Welding processes were accomplished by means of a 600 W Continuous Wave (CW) fiber laser instrument in bead on plate manner with 60, 80 and 100 J mm−1 heat inputs. δ-TRIP Steel samples were similar in chemical composition and only contained different Nb (40Nb: 0.040 & 72Nb: 0.072 wt.% Niobium) amounts. Elevation of heat input resulted in changes in microstructure and hardness properties, which are desirable for welders to guarantee safe joints in engineering structures. An increase in the heat input can lead to reduction of the austenite in weld metals of both steel sheets. The reduction of the austenite could be attributed to the increase in δ-ferrite volume fraction which was induced by availability of sufficient time for segregation of aluminum and formation of more dendrite structured δ-ferrite at lower cooling rates. Increase in δ-ferrite content results in decreasing austenite content required for transformation of austenite to martensite. The direct consequence of a decrease in the martensite volume fraction is reduction of hardness. It is shown that an increase in the heat input from 60 to 100 J mm−1 results in reduction of hardness difference between weld and base metals by 40% and 37% for 40Nb and 72Nb steels respectively.

In this experiment, we systematically investigated the microstructure evolution, mechanical properties, and deformation behaviors as functions of annealing temperature using cold-rolled Fe-0.05C–6Mn–1Al-1.5Si steel. Almost all annealed specimens are composed of the equiaxed and granular α-ferrite (α) grains due to recrystallization, reversed austenite (γ) grains because of reversed transformation from deformed martensite, and fibrous δ-ferrite (δ) grains only undergoing recovery during intercritical annealing except for 760 °C. It is interesting that several annealing twins are formed within γ grains. The outstanding combination of strength and ductility is obtained for annealing at 740 °C. The tensile strength and total elongation are 980 MPa and 32.1%, which are attributed to the ultrafine grains and optimal TRIP effect associated with rational γ content and stability. A phenomenon that yield point elongation (YPE) gradually shortens with increased γ content and decreased γ stability is observed. What's more, the mechanism that active α′ formation can promote the improvement of work hardening rate and further curtail YPE is verified using deep-cryogenic treatment. Based on SEM observation, microscopic strain of δ grains appears nearly consistent with matrix (α and γ grains) during tensile process, although δ phase presents as fibrous morphology with coarse size.

A dual phase structure consisting of ferrite and martensite has been achieved in Ti-bearing steels microalloyed with Mo or Cu, respectively, which were treated under different austenitizing and hot deformation conditions to investigate the effects of second microalloying elements and thermomechanical processes on the microstructural evolution and mechanical properties. The results showed the largest microhardness values, 343 HV0.1 for Ti–Mo steel and 307 HV0.1 for Ti–Cu steel, in microalloyed steels austenitized at 1200 °C with 30% deformation strain. Furthermore, critical patent analysis revealed that higher tensile strength is achieved in a Ti–Mo steel having a larger Ti/Mo atomic ratio, but no such relationship between tensile strength and Ti/Cu atomic ratio applies to Ti–Cu steel. This finding can be ascribed to the different metallurgical effects of Mo and Cu in the Ti-bearing steels. For example, the addition of Mo in a Ti-bearing steel leads to tiny carbides due to the decrease in coarsening via the synergistic effect of Ti and Mo. On the other hand, the separate precipitation of TiC and Cu in the Ti-bearing steels is consistent with the results of patent analysis. That is, the tensile strength of these steels is not associated with the Ti/Cu atomic ratio.

Herein, the hot compression of a super austenitic stainless steel (SASS) containing 7Mo–0.46N–0.02Ce is conducted at different temperatures (900–1200 °C) under a strain rate of 10 s−1. The effect of angle between solidification direction of columnar crystals and loading direction (0°, 30°, 60° and 90°) on microstructural evolution of SASS is studied using OM and EBSD. The results reveal that, at low temperatures of 900 °C and 1000 °C, the dynamic recrystallization (DRX) degree of the 30° and 60° samples is higher than that of the 0° and 90° samples, however, the complete DRX has not occurred. At high temperatures of 1100 °C and 1200 °C, the DRX degree of SASS increases with the decrease of angle between solidification direction of columnar crystals and loading direction. Three kinds of DRX mechanisms for samples with different columnar crystal characteristics are observed, i.e., discontinuous dynamic recrystallization (DDRX), continuous dynamic recrystallization (CDRX) and a combination of DDRX + CDRX mechanism. However, under the same deformation conditions, preferentially triggered and dominant DRX mechanisms of samples with different columnar crystal characteristics are different. In the 0° and 90° samples, a large number of high angle grain boundaries (15° ≤ HAGB ≤65°) are developed, and new DRX grains are formed on them. While in the 30° and 60° samples, preferential expansion nucleation and growth of DRX grains take place on original GBs. At 1200 °C, the DRX degree of SASS reaches a maximum of ∼0.97 when the angle between solidification direction of columnar crystals and loading direction is 0°.

In this work, effect of martensite pre-quenching on the subsequent bainite transformation kinetics of GCr15 bearing steel has been investigated by means of dilatometry. The results show that the pre-quenched martensite is significantly accelerate nucleation of subsequent bainite transformation in comparison with direct bainite austempering. Meanwhile, specimen of martensite pre-quenching at 200 °C has the shortest incubation period of bainite transformation at 240 °C. Moreover, the transformation rate of bainite transformation after martensite pre-quenching is faster than direct bainite austempering in the initial growth stage, and decrease with the decreasing of martensite pre-quenching temperature. Compared with the conventional quenched and tempered (QT) specimen, the tensile strength is slightly decrease from 2170 MPa to 2143 MPa, but the impact toughness is obviously increase from 43 J to 71 J in specimen heat-treated by martensite pre-quenching at 200 °C and subsequent bainite transformation at 240 °C. In addition, the mechanical stability of retained austenite in all martensite pre-quenching specimens are higher than that of QT specimen.

This paper aims at the phase identification and quantification in transformation induced plasticity duplex stainless steel (TDSS) base and weld metal containing ferrite, austenite, and martensite. Light optical microscopy (LOM) and electron backscatter diffraction (EBSD) analysis were employed to analyze phases. Samples were either mechanically or electrolytically polished to study the effect of the preparation technique. Mechanical polishing produced up to 26% strain-induced martensite. Electrolytic polishing with 150 g citric acid, 300 g distilled water, 600 mL H3PO4, and 450 mL H2SO4 resulted in martensite free surfaces, providing high-quality samples for EBSD analysis. Martensite identification was challenging both with LOM, due to the similar etching response of ferrite and martensite, and with EBSD, due to the similar lattice structures of ferrite and martensite. An optimized Beraha color etching procedure was developed that etched martensite distinctively. A novel step-by-step EBSD methodology was also introduced considering grain size and orientation, which successfully identified and quantified martensite as well as ferrite and austenite in the studied TDSS. Although here applied to a TDSS, the presented EBSD methodology is general and can, in combination with knowledge of the metallurgy of the specific material and with suitable adaption, be applied to a multitude of multiphase materials. It is also general in the sense that it can be used for base material and weld metals as well as additive manufactured materials. This study received support from the EU-project H2020-MSCA-RISE-2018 Number 823786, i-Weld, and the Swedish Agency for Economic and Regional Growth through the European Union–European Development Fund

A novel wire-powder hybrid arc additive manufacturing (WPHAAM) was applied for melting zone nitridizing to avoid the deterioration effect caused by the loss of nitrogen in high nitrogen steel. A designed Cr-Mn-N wire with 0.79 wt% of nitrogen (HNS6) was used to build a high nitrogen wall body by introducing WPHAAM method. The influence of nitrogen content on solidification behavior, microstructure, and tensile properties were studied in the as-built conditions. With the increase of amount of feeding powder, the solidification mode of the deposited wall changes from primary ferrite with second-phase austenite (FA mode) to primary austenite with second-phase ferrite (AF mode), and the mechanical properties are enhanced. When the powder feeding rate reaches 0.33 g/min, the solidification changes to A mode, and the deposited metal is austenite. The ultimate tensile strength and elongation of the deposited metal are 1014 MPa and 50.8% respectively.

The focus of this study is to analyze hydrogen embrittlement susceptibility of a modified AISI 4130 steel by means of incremental step loading tests. Three different microstructures with a hardness of 40 HRC were analyzed: martensite with large and small prior austenite grains and dual-phase (martensite/ferrite). According to the results, the dual-phase microstructure presented the lowest hydrogen embrittlement susceptibility and martensite with large prior austenite grains, the highest. This behavior was attributed to the lower fraction of high-angle boundaries presented by the martensite with large prior austenite grains, which led to a higher diffusible hydrogen content. Moreover, the ferrite local deformation in the dual-phase microstructure enhanced its hydrogen embrittlement resistance by lowering the stress concentration. A synergic effect of decohesion and localized plasticity was identified on the hydrogen induced fracture of the tested microstructures leading to an intergranular + quasi-cleavage fracture in the martensite and quasi-cleavage in the dual-phase microstructure.

In this research, the effects of annealing temperature (500, 550, and 600 °C) on the microstructure and mechanical properties of a conventionally (1 cycle) and severely (6 cycles) deformed Fe–24Ni martensitic steel, processed by accumulative roll bonding (ARB), were investigated. Electron backscattered diffraction (EBSD) analysis revealed that annealing at 500 and 550 °C for 30 min was insufficient for completing the reverse martensite transformation, and consequently, the microstructure consisted of austenite and martensite. However, complete reverse martensitic transformation has been accomplished after annealing at 600 °C for 30 min for both deformed samples. Both yield strength (YS) and ultimate tensile strength (UTS) were increased after first and sixth cycle of rolling. Subsequent, annealing led to a decrease in YS and UTS with improvement in uniform elongation ( e u ). In addition, the work hardenability was also improved by annealing the deformed samples.

High-strength bainitic steels have created a lot of interest in recent times because of their excellent combination of strength, ductility, toughness, and high ballistic mass efficiency. Bainitic steels have great potential in the fabrication of steel armor plates. Although various approaches and methods have been conducted to utilize the retained austenite (RA) in the bainitic matrix to control mechanical properties, very few attempts have been conducted to improve ballistic performance utilizing transformation-induced plasticity (TRIP) mechanism. In this study, high-strength bainitic steels were designed by controlling the time of austempering process to have various volume fractions and stability of RA while maintaining high hardness. The dynamic compressive and ballistic impact tests were conducted, and the relation between the effects of TRIP on ballistic performance and the adiabatic shear band (ASB) formation was analyzed. Our results show for the first time that an active TRIP mechanism achieved from a large quantity of metastable RA can significantly enhance the ballistic performance of high-strength bainitic steels because of the improved resistance to ASB formation. Thus, the ballistic performance can be effectively improved by a very short austempering time, which suggests that the utilization of active TRIP behavior via tuning RA acts as a primary mechanism for significantly enhancing the ballistic performance of high-strength bainitic steels.

Journal of materials science & technology : JMST 85, 30-43 (2021). doi:10.1016/j.jmst.2020.12.069, Published by Elsevier, Amsterdam

In this research, the wire arc additive manufacturing (WAAM) of duplex stainless steel (DSS) was firstly conducted using flux-cored wires as the feedstock material. Homogeneous microstructure was obtained in the WAAM DSS component fabricated using the commercial E2209 welding wire as the filler material. However, the average austenite content reached up to 74%, which exceeded the standard limitation. Electron backscatter diffraction (EBSD) measurements indicated that the austenite phase exhibited strong 〈101〉//Z texture, and the ferrite phase exhibited strong 〈001〉//Z texture. Evaluations of the mechanical properties revealed that the strength of the WAAM DSS component fulfilled the standard requirements of the cast DSS components, and its impact toughness at −40 °C exceeded that of commercial hot rolled LDX 2101 DSS plate. To modify the austenite content in the as-deposited DSS, two novel flux-cored wires were designed and produced for the flux-cored wire arc-additive manufacturing (FCWA-AM) process. These materials allowed the reduction of the austenite ratios to 37% and 45% in the as-deposited DSS components. The results of this work demonstrated that the FCWA-AM technique is an applicable WAAM method for producing DSS components with desired microstructures and good mechanical properties.

In recent years, iron (Fe) based degradable metal is explored as an alternative to permanent fracture fixation devices. In the present work, copper (Cu) is added in Fe-Mn system to enhance the degradation rate and antimicrobial properties. Fe-Mn-xCu (x = 0.9, 5 and 10 wt.%) alloys are prepared by the melting-casting-forging route. XRD analysis confirms austenite phase stabilization due to the presence of Mn and Cu. As predicted by Thermo-Calc calculations, Cu rich phase precipitations are noticed along the austenite grain boundaries. Degradation behaviours of Cu added Fe-Mn alloys are investigated through static immersion and electrochemical polarization where enhanced degradation is found for higher Cu added alloys. When challenged against E.Coli bacteria, the Fe-Mn-Cu alloy media extract shows a significant bactericidal effect compare to the base alloy. In vitro cytocompatibility studies, as determined using MG63 and MC3T3-E1 cell lines, indicate increased cell density as a function of time for all the alloys. When implanted in rabbit femur, the newly developed alloy does not show any kind of tissue necrosis around the implants. Better osteogenesis and higher new bone formation are observed with Fe-Mn-10Cu alloy as evident from micro-computed tomography (μ-CT) and fluorochrome labelling.