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The aim of this paper is to investigate the mechanical properties of Nickel Aluminium Bronze (NAB) alloying with Niobium (Nb) and Yttrium (Y) rare earth metals. NAB alloy frequently used in the aqueous solution as well as less widely used deployed materials were studied. To avoid failures due to aqueous environment. Niobium (Nb) and Yttrium as chosen alloying addition with NAB. The Nb and Y rare earth element which acts as stabilizing element to existing NAB system to optimize the mechanical properties. The NAB with alloying elements processed in the vacuum induction furnace by means of predetermined parameters. After casting, the samples were tested for the mechanical properties like tensile and Brinell hardness to ensure improvements with the master NAB system. At the same time, the characterization techniques SEM and EDAX with mapping analysis confirmed the chemical proportions of the elements in the developed NAB with proposed NAB (Nb) and NAB (Y) alloys. A comparative study is to be made for the NAB with Nb and Y under aqueous environment based for the developed alloys.

Cast hyper duplex stainless steel (HDSS) was modified with a stabilizer Niobium to suppress the formation of deleterious intermetallic phases. Based on the Thermo calc, samples were heat treated at 900 °C and 1150 °C. Intergranular corrosion resistance was studied with the help of double loop electrochemical potentiokinetic reactivation (DL-EPR) method. Surface of the specimen was characterized by optical microscope, SEM coupled with EDS. Addition of niobium retards the formation of chromium carbides and the same was confirmed with EDS point analysis. DL-EPR shows the better degree of sensitization for niobium stabilized cast HDSS than the regular HDSS.

This article reviews the current state of the art in understanding manganese steels. The standard manganese steel (Hadfield’s Manganese) has roughly 12% manganese and 1.2% carbon. This approximate 10 to 1 ratio from Hadfield’s work. Then there is High manganese steels with 18–31% Mn with higher carbon content upto 1.9%, higher manganese grades require elevated carbon levels in order to achieve the desired increase in service life. And other being Lean manganese steels with 5–8% Mn, 1%C and 1.5%Mo to help stabilize the austenite. Medium Mn steels had been investigated due to their excellent balance between material cost and mechanical properties. Consisting of a single α′ martensite phase in hot and cold rolled states and multiphases after inter-critical annealing. The steels exhibit high strength and good ductility due to transformation induced plasticity occurring in retained γ γR, whose volume fraction is approximately 0.2–0.4. There another deformation mechanism called twinning induced plasticity (TWIP) enhances certain Manganese steels. TWIP steels exhibit very high strain hardening rate due to the deformation twins taking advantages of dynamic Hall-Petch effect. In TWIP steels the manganese content varies between 20 and 30%. In spite of some very desirable properties, it also poses a challenge in materials production. Reducing Mn content in TWIP steels and addition of Al reduced the tendency for delayed cracking. Since the Mn content in TWIP steels influences the stacking fault energy (SFE) which plays major role deformation mechanism. This review concludes by suggesting fundamental research needs to promote the design of manganese steels with improved properties and performance.

An investigation was carried in Nickel Aluminium Bronze (NAB) alloyed with Niobium (Nb) and Yttrium (Y) to study the effect of the microstructure for onshore applications. Nickel Aluminium Bronze is broadly used in aqueous atmospheres due to their good mechanical and corrosion resistance properties. The presence of destructive species in aqueous water initiates the corrosion of the engineering modules is inevitable. In-order to optimize the corrosion resistance Nb and Y were added as (1%, 2% & 3%) respectively in the master NAB. The specimens were exposed to the immersion test in NaCl solution. To create the behavior of corrosion and succeeding erosion, altered immersions hours were selected as 8, 16, 24, 32, 40, 48 and 54 h. The mass loss measurements were obtained after the completion of the individual specified time to calculate corrosion rates (CR). Solid particle erosion (SPE) investigations were also carried out on the developed alloys. The size of the particle which is used in the investigation is 50 µm. Corrosion rate was calculated and it is correlated with the immersion time. Scanning electron microscopy (SEM) investigations were observed for the corroded and eroded specimens.

Metallic corrosion is a major concern for bogie side frames used in railways. The exposure to harsh environment is unavoidable and a protective coating is one possible solution. In this work, tungsten-based carbide coating was produced on EN10025/5 steel. The corrosion properties of the coating were studied using potentio dynamic polarization test using actual field conditions and using ASTM standard 3.5% NaCl. The coating was subjected to slurry exposure using waterjet erosion tester. The microstructure of the eroded area was studied for understanding the wear mechanism. The corrosion and erosion of the coating was compared with the base material. It was evident that tungsten-based carbide coating increases the corrosion and erosion resistance of steel in railway application.

Duplex stainless steels (DSS) exhibit excellent corrosion resistance and mechanical properties to the severe environments and hence are used in many engineering applications such as oil and marine industries, chemical storage, nuclear power plants, and many more. These are used as valves, fittings, and pipes to suck the crude oil in oil fields. Austenite (γ) and ferrite (δ) phases constitute the microstructure of DSS. However, one needs to control both the phases towards making it lucrative in desired applications. Investigations on tribological behavior of cast DSS are limited. The current work focuses on optimizing the wear parameters for slurry jet erosion and analyzing their effect on wear of the 5A DSS. Grey relation analysis (GRA) and Taguchi design of experiments have been used for optimization. Slurry jet erosion tester was used investigate the response of the material to various designed experiments. Worn-out surfaces morphologies and wear mechanisms were revealed using Scanning electron microscopy (SEM), whereas white light interferometer was used to understand 3D morphologies the surfaces.

AlCoCrNi alloy was modified by adding Mo to increase its corrosion resistance. Mo was successfully added to the alloy using mechanical milling. All the five constituents of the alloy were milled in a high-energy planetary ball-mill for 20 h. The effective concentration of Mo in the alloy was 10%. At equal intervals, samples were taken for phase formation studies using X-ray diffractional analysis (XRD). The micro-structural characterization was carried out to confirm the homogeneity of the alloy using Field emission scanning electron microscopy (FESEM). The resultant high entropy alloy (HEA) powder was thermally sprayed over a 316l substrate using High-velocity Oxy-fuel (HVOF) technique. Corrosion characteristics of the coating were studied using potentio-dynamic polarization (PDP) test under standard condition. The corrosion properties of the coating were compared with conventional NiCrSiB corrosion resistant coating. The AlCoCrMoNi HEA system offers better resistance to corrosion than NiCrSiB coating.

Mg-9Li-3Al magnesium alloys with varied level of Nd added (i.e., 0-2.0wt. %) alloys were prepared electric resistance stir casting furnace under controlled inert gas atmosphere. Impact of Nd addition on metallographical changes and mechanical characteristics of as-cast alloys were analyzed by using an OM, XRD, SEM with EDS. The metallography evaluation revealed that adding Nd refines the microstructures due to formation of Al2Nd and Al11Nd3 precipitates, these precipitates exists together with α-Mg, β-Li, AlLi, MgLi2Al phases in the alloy. Furthermore, adding Nd improves the mechanical strength and elongation. 1.5wt.% Nd added alloy displayed the better mechanical characteristics; UTS is 166MPa; Elongation 16.87%.

Dissimilar welding of 3mm thickness of AISI 304L austenitic stainless steel plate and AISI 430 ferritic stainless steel plates were performed by Tungsten Inert Gas welding without any filler material by using argon as shielding gas. Welding is carried out according to set of combinations of welding parameters such as welding current (levels of 135,140,145 Ampere), welding speed (levels of 105, 110, 115 mm/min) and shielding gas flow rate (of levels 5,10,15 Litre/min) obtained through Taguchi L9 orthogonal approach for maximizing the ultimate tensile strength by using MiniTab software . Radiography test was performed to know the soundness of the welds. Tensile specimens are fabricated as per ASTM E8 standard for tensile testing. Microstructural observations of the weld are performed. Correlations have been obtained to know the effect of welding speed, welding current and shielding gas flow rate on tensile strength and an optimum level of parameter is obtained at welding current of 145 Ampere, welding speed of 115 mm/min and shielding gas flow rate of 5 Litre/min.

The effect of cerium addition on AZ91 magnesium alloy and its influence on stress corrosion cracking (SCC) were studied using constant load proof ring testing NaCl-K2CrO4 and ASTM D1384 solutions at 70 and 80% of yield stress, respectively. The investigation revealed that the optimum grain refinement of desired phases occurred with 0.5% addition of cerium. The addition levels of cerium above 1.5 wt.% to AZ91 alloy resulted in premature failures due to poor SCC resistance in both solutions (K2CrO4 and ASTM D1384 solutions). The microstructural studies of the experimental alloys were characterized by using optical and scanning electron microscopy. The elemental compositions of cerium-added AZ91 magnesium alloys were studied by energy-dispersive spectroscopy. The results indicate that the mode of SCC failure was found to be transgranular in nature along with secondary cracks containing cleavages which resulted from the hydrogen embrittlement and anodic dissolution phenomena. The AZ91 alloy with 0.5 wt.% cerium exhibits better mechanical properties and high stress corrosion resistance.

As-cast Mg-9Li-3Al-xNd (x = 0-2.0 wt.%, with the variation of 0.5wt.%) magnesium alloys were prepared through casting in electrical induction melting furnace under a controlled inert gas atmosphere. Influences of Nd over the metallography changes and corrosion characteristics of Mg-9Li-3Al alloys have been examined by following techniques are OM, XRD, SEM and potentio-dynamic polarization (PDP) test. The results illustrate that adding Nd modifies the continuous β-Li phases into discontinuous phase by the formation of new precipitates such as Al2Nd and Al11Nd3. Meanwhile, the grain sizes of Mg-9Li-3Al-xNd alloys reduced with respect to the increasing Nd content. PDP results disclose that the Nd addition reduces the corrosion current density (icorr) of Mg-9Li-3Al alloys which can be essentially produced by grain refinemente.

In this present research, the coatings of SA209-T1 using high velocity oxygen fuel were employed for the application of boiler tubes. Due to the adaptation of corrosion easy in boiler material, the research of those properties is significant because of its criticality and functionality during the service time. A right coating was found and applied on the SA209-T1 surface against corrosive environments. Good corrosion resistance is achieved by WC-flyash coatings applied on SA209-T1 substrate. The 90% WC-10% flyash coatings were found to be more protective followed by SA209-T1 steel. WC-flyash covering was tracked down so that the covering is compelling to secure the SA209-T1 steel substrate. It is reasoned that the arrangement of NiO, Cr2O3, CoO, and NiCr2O4 could add to the advancement of consumption opposition in coatings. The steel of uncoated endured erosion as extraordinary stripping and spalling of the scale, which could be because of the development of Fe2O3 oxide scale unprotectively. This paper reveals the performance, applications, and development of 90wt.% WC and 10wt.% fly ash through HVOF coating in SA209-T1 for electrochemical corrosion studies at room temperature.

Duplex stainless steel (DSS) is having an equal fraction of ferrite and austenite. Chromium, Nickel, Molybdenum, and few minor alloying elements constitute a DSS system, which makes metallurgy of the system complex. Proper heat treatment is need of the hour when it comes to expecting desired properties from the material, subjected to a specific working environment. DSS is one of the favourite choices for oil and gas industries. This study focuses on optimizing the heat treatment parameters and heat treating the as-cast 5A DSS and investigating microstructural evolution of the material subjected to various quenchants such as brine, water, and polyethylene glycol. Heat treatment temperatures, quenching media, and the quenching time have been selected in accordance with ASTM standards. Thermocalc TCFE8 database is being used for understanding the material response to various heat treating temperatures.

Niobium addition to base alloy significantly reduces the formation of deleterious phases, in particular, sigma phase when the material is sensitized at 900 °C. In this paper, hyper-duplex stainless steel with 0.47% of Niobium (Nb + CD3MWN - 7A) was casted using induction melting furnace and then heat-treated under two different heat treatment temperatures of 1160 °C and 900 °C to explore the properties such as microstructure and hardness for further study. The erosion test was carried out in air-jet erosion tester at room temperature with different erodent velocities. The study was done with a constant impact angle of 45°. Microstructure analysis was carried on two different heat-treated samples as well as on eroded samples using scanning electron microscope coupled with energy-dispersive analysis spectroscopy to confirm the presence Niobium carbide precipitation in sensitized sample at grain boundaries. Erosion test results showed that erosion rate is lower in sensitized sample when compared to solutionized sample because of their higher hardness in sensitized sample.

High cost imported components of seamless steel tube manufacturing plants wear frequently and need replacement to ensure the quality of the product. Hard chrome plating, which is time consuming and hazardous, is conventionally used to restore the original dimension of the worn-out surface of the machine components. High Velocity Oxy-Fuel (HVOF) thermal spray coatings with NiCrBSi super alloy powder and Cr3C2 NiCr75/25 alloy powder applied on a 50CrMo4 (DIN-1.7228) chromium molybdenum alloy steel, the material of the wear prone machine component, were evaluated for use as an alternative for hard chrome plating in this present work. The coating characteristics are evaluated using abrasive wear test, sliding wear test and microscopic analysis, hardness test, etc. The study results revealed that the HVOF based NiCrBSi and Cr3C2NiCr75/25 coatings have hardness in the range of 800–900 HV0.3, sliding wear rate in the range of 50–60 µm and surface finish around 5 microns. Cr3C2 NiCr75/25 coating is observed to be a better option out of the two coatings evaluated for the selected application.

This research aims to characterize the bead geometry, metallurgical aspects of the optimized maraging steel (250 grade) weld track processed by autogenous gas tungsten arc welding technique. Design of experiments was used to determine the weld track possessing optimal bead geometry. Welding speed and current were the parameters considered for optimization. Depth of penetration and bead width were the adjudicating parameters for optimality. Taguchi analysis showed that welding current is directly proportional to depth and width whereas weld speed was indirectly proportional. Statistical analysis indicated that welding speed has affected the depth of penetration and different current levels have affected the width of the weld bead linearly. Optical microscopy and SEM/EDAX analysis were done to investigate the post weld microstructural changes. X-Ray Diffraction were done to understand the phase formations.

Intergranular corrosion of duplex stainless steel is a major concern in high corrosive environments. Interstitial stabilization of alloy is a possible technique for susceptibility to intergranular corrosion. In this paper, zirconium addition was made to 5A grade cast duplex stainless steel in order to achieve the stabilization. Addition of zirconium forms a mixture of zirconium carbides and nitrides which suppress the chromium depletion and thus increase the intergranular corrosion resistance. The metallurgical characterization was carried out on the specimens by means of optical microscopy, scanning electron microscopy, energy-dispersive spectroscopy, and x-ray diffractometry. Corrosion behavior investigation using oxalic acid etch test and double-loop electrochemical potentiokinetic reactivation technique results underline the superior corrosion-resistant property of zirconium-added cast duplex stainless steel.

Dissimilar metal joints are of great interest in many industries. This paper deals with the study on dissimilar fillet joints made by tungsten inert gas welding (TIG) with various shielding gas and filler combinations. Design of experiments performed to optimize the right combination of the process. Metallurgical and mechanical characterization on the dissimilar joints made by TIG welding process was carried out and compared with dissimilar joints made by friction welding. Weldment corrosion behavior was studied by using the potentiodynamic instrument. Dissimilar welding is done by TIG welding process using duplex stainless filler wire with argon shielding gas shown an appreciable increase in pull out strength while compared with other combinations. The dissimilar joint made by duplex stainless steel filler (ER2209) exhibits better pitting corrosion resistance than austenitic stainless steel filler (ER309L).

Mg–8Li–3Al+xCe alloys (x = 0.5wt%, 1.0wt%, and 1.5wt%) were prepared through a casting route in an electric resistance furnace under a controlled atmosphere. The cast alloys were characterized by X-ray diffraction, optical microscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The corrosion behavior of the as-cast Mg–8Li–3Al+xCe alloys were studied under salt spray tests in 3.5wt% NaCl solution at 35°C, in accordance with standard ASTM B–117, in conjunction with potentiodynamic polarization (PDP) tests. The results show that the addition of Ce to Mg–8Li–3Al (LA83) alloy results in the formation of Al2Ce intermetallic phase, refines both the α-Mg phase and the Mg17Al12 intermetallic phase, and then increases the microhardness of the alloys. The results of PDP and salt spray tests reveal that an increase in Ce content to 1.5wt% decreases the corrosion rate. The best corrosion resistance is observed for the LA83 alloy sample with 1.0wt% Ce.

Equi-atomic and non equi-atomic multi-component systems were synthesized through different routes to form high-entropy single solid solution. One such high-entropy alloy (HEA) with hexanary composition AlCoCrCuFeZn x was synthesized using mechanical alloying. The effect of zinc variation on the crystal structure and phase formation was characterized using XRD, FESEM with EDS and TEM. The synthesis resulted in both equi-atomic and non equi-atomic nano crystalline AlCoCrCuFeZn with a crystallite size less than 10 nm.

The corrosion behaviour of Mg–6Al–1Zn + XCe (where X = 0.5, 1.0, 1.5 and 2.0 wt% Ce) alloys, aged for 18 h at different temperatures of 180 °C, 200 °C, 220 °C and 240 °C, was studied in 3.5 wt% NaCl solution. The salt spray test was conducted in accordance with ASTM-B117 standard (fog test). The corrosion morphologies, corrosion rate and the composition of the corrosion products were investigated by X-ray Diffraction (XRD), Optical Microscopy (OM) and Scanning Electron Microscopy (SEM) techniques. The results show the cerium addition and ageing treatment has significantly influenced the corrosion morphologies and the corrosion rate. In AZ61 alloy, the intermetallic β (Mg17Al12) phase acts as a corrosion barrier and upon ageing the Al4Ce phase precipitates along the α grain boundaries. The precipitation modifies the β phase to form more continuous network which subsequently reduces the corrosion attack in the chlorine environment. Salt spray test result shows the AZ61 alloy with 1.5 wt% Ce aged at 220 °C exhibits the better corrosion resistance.

The role of metal matrix composites (MMCs) has gained huge momentum in various researches as well as in industrial applications due to their high stiffness and higher strength to weight ratio. It helps in achieving enormous weight reduction without compromising the strength of the material. In this study, a novel attempt was made to fabricate MMCs with martensitic stainless steel as matrix and titanium diboride (TiB2) as reinforcement. The AISI 420 matrix with different weight percentages (1%, 2%, and 4%) of TiB2 reinforcement was fabricated by vacuum induction melting technique (VIM). The aim of this study was to analyze the influence of TiB2 particle addition on the mechanical and tribological properties of AISI 420 composites. X-ray diffraction studies revealed the presence of TiB2 phase in the composite along with peak shifting and broadening of the steel matrix due to induced strain. Optical microscopy showed the distribution of TiB2 particles in the matrix along with a significant amount of grain refinement of the composite due to the addition of TiB2. Microhardness results showed that the presence of TiB2 improved the hardness with AISI 420/4%TiB2 composite possessing the maximum hardness. Tensile test results indicated a significant improvement in the ultimate tensile and yield strength of the composite with the addition of TiB2. The wear tests were carried out on a pin on disc tribometer for various loads at a different sliding distance for steady sliding velocity. The dispersion of TiB2 particle helped in achieving better wear resistance of the composites. Wear surface morphology was carried out to explore the wear mechanisms. Among the various wear mechanisms, abrasion and oxidation phenomena dominated in the composites. Taguchi optimization technique predicted that wt% of TiB2 and applied load as influencing factors on the wear rate of the material.

Centrifugal pumps used in the lignite mines encounter erosive wear problems, leading to a disastrous failure of the pump casings. This paper attempts to evaluate the erosive wear resistance of Ni-Hard 4, high-chromium iron, and Cast CD4MCu duplex stainless steel (DSS), for mining conditions. The prepared test coupons were subjected to an erosion test by varying the impingement velocity and the angle of impingement, under two different pH conditions of 3 and 7, which pertained to the mining conditions. XRD analysis was carried out to confirm the phases present in the alloy. The eroded surface was subjected to SEM analysis to identify the erosion mechanisms. The surface degradation of Ni-Hard 4 and high-chromium iron came from a low-angle abrasion with a grooving and plowing mechanism at a low angle of impingement. At normal impingement, deep indentations resulted in lips and crater formations, leading to degradation of the surface in a brittle manner. A combined extrusion-forging mechanism is observed in the CD4MCu DSS surface at all the impingement angles.

The corrosion behavior of cast Mg–6Al–1Zn + XCa (Where X = 0.5,1.0,1.5 and 2.0 wt.% Ca) magnesium alloy, aged at different temperatures of 180 °C, 200 °C, 220 °C and 240 °C was investigated in accelerated corrosion test chamber according to ASTM-B117 Standard (salt spray test). The exposed alloys were characterized by X-Ray Diffraction (XRD), Optical Microscopy (OM) and Scanning Electron Microscopy (SEM) techniques. The microstructural refinement due to calcium addition and ageing treatment results in the improvement of corrosion resistance of the experimental alloy. Corrosion rate decreases due to fine precipitation of the β (Mg 17 Al 12 ) phase distributed along the α-grain boundaries during ageing. Intermetallic phases act as a barrier, which makes the alloy more resistant to corrosion. Results found that better corrosion resistance of the alloy was observed in Mg–6Al–1Zn + 1.5 wt.% Ca with 180 °C ageing temperature. The corrosion behavior of Mg–6Al–1Zn + XCa alloy exhibited by ASTM B117 salt spray testing and electrochemical polarization measurements showed similar trends concluding that the calcium addition and ageing temperature decreases the corrosion rate.

The effect of yttrium addition on the microstructure of Mg-6Al-1Zn alloy was investigated by optical microscopy, x-ray diffraction analysis, and scanning electron microscopy. The experimental alloys were prepared by melting high-purity Mg, Al, Zn, and Y, respectively. Melting was carried out in a Inconel 718 crucible under SF6 and ultra pure Ar (99.999%) gas mixture environment using electric arc furnace. The corrosion behavior of Mg-6Al-1Zn+xYttrium (x = 0.5, 1.0 and 1.5 wt.% Y) magnesium alloy with different levels of yttrium additions was studied in 3.5 wt.% NaCl solution. Microstructure of yttrium-added alloy shows that higher grainrefinement is obtained in Mg-6Al-1Zn+0.5wt.%Y. Increasing yttrium content reduces the size of α-grain and alters the distribution of the β-phase (Mg17Al12) from continuous network morphology to small and dispersive distribution. It forms secondary intermetallic phase Al2Y which has high melting point along the grain boundary. The corrosion resistance of Mg-6Al-1Zn magnesium alloy improved with addition of Yttrium. It was confirmed by the results of electrochemical polarization test. Based on the polarization curves, it is seen that fine precipitates of Al-Y intermetallic phase in Mg-6Al-1Zn alloy decrease the corrosion current density, thereby improving the corrosion resistance of the Mg-6Al-1Zn magnesium alloy.

The corrosion behavior of AZ61 alloyed with 0.5, 1.0, 1.5 and 2.0% Ca were studied by potentiostatic polarization technique in 3.5wt. % NaCl solution and the further effect of corrosion behavior have been studied after aging at different temperature in a controlled environment.The results show that the calcium addition enhances the corrosion resistance.Simultaneously when the alloy is aged at 180°C, the corrosion resistance has improved. This study also reveals the interesting microstructural change that isresponsible for the improved corrosion resistance. Themicrostructural characterization of this alloy was studied using Optical and Scanning Electron Microscopy (SEM).

Grey cast iron material was taken up for the investigation with and without the application of NiCrBSi coating by high velocity oxyfuel process on its substrate. Prominent influencing factors such as velocity and angle of impingement were chosen for the study of the erosive wear behaviour involving two different pH conditions of 3 and 7 that conform to the mining conditions. X-ray diffraction characterisation was used to identify and confirm the phase formation in the coating. Wear morphology was also studied using scanning electron microscopy characterisation techniques. NiCrBSi coating at low angles of impact reveals that the degradation is by shallow ploughing and abrasion. At normal impact, erosion takes place by deep indentation that forms lips and craters, which are subsequently removed as platelets by a fatigue process. In the case of base material, the material removal from the surface is predominantly by ploughing mechanism.

Nihard Grade-4, a nickel-bearing cast iron widely used in slurry pumps and hydrodynamic components, is evaluated for its erosive wear response under mining conditions using a statistical approach. Experiments were conducted by varying the factors namely velocity, slurry concentration, angle of impingement, and pH in three levels, using L9 orthogonal array. Analysis of variance was used to rank the factors influencing erosive wear. The results indicate that velocity is the most influencing factor followed by the angle of impingement, slurry concentration, and pH. Interaction effects of velocity, slurry concentration, angle of impingement, and pH on erosion rate have been discussed. Wear morphology was also studied using SEM characterization technique. At lower angle (30°) of impingement, the erosion of material is by micro fracture and shallow ploughing with the plastic deformation of the ductile austenitic matrix. At the normal angle (90°) of impingement, the material loss from the surface is found because of deep indentation, forming protruded lips which are removed by means of repeated impact of the erodent.

Weld cladding is a process of depositing a thick layer of anticorrosive metal on a corrosive substrate surface to impart better corrosion resistance properties. In weld cladding process, the difficulty generally encountered will be the problem of selecting optimum combination of input process parameters to achieve the desired dilution level. Until recently trial and error methods were employed to determine the optimum process parameters, which result in wastage of cost and time. This paper focuses on optimization of GMAW process parameters, which are used for deposition of austenitic stainless steel on low carbon structural steel plates. Experiments were conducted based on four-factor five-level central composite rotatable design with full replication technique. Mathematical models relating to gas metal arc welding process parameters to clad bead geometry were developed using multiple regression method. Developed mathematical models are helpful in predicting the clad bead geometry and in setting process parameters at optimum values to accomplish the desirable dilution level at relatively low cost with a high degree of reproducibility. The accuracy of the results was tested by conducting conformity tests using the same experimental set up. Moreover, Genetic Algorithm tool with GUI available in MATLAB 7.0 was used to optimize the process parameters to achieve optimum dilution.

Surface properties decide the fatigue, wear and corrosion behavior of a material. Hence their performance can be improved by surface modifications. Friction Stir Processing (FSP) is a promising technique to develop surface composite. The aim of the present study is to develop defect free surface composite of Al 5083 alloy reinforced with TiC particles and investigate the particle distribution in the matrix, mechanical properties and wear behavior of the composites. Microstructural observations were carried out by using optical and scanning electron microscopy (SEM). The microstructural studies revealed that distribution of particles were more uniform in samples subjected to double pass than the single pass FSP. The microhardness profiles along top surface and across the cross section of the processed samples were evaluated. The average hardness along the top surface was found to increase by 27.27%, as compared to that of the base metal (88Hv). The particles were incorporated maximum average depth about 250μm in the surface composite. The slurry erosion tests revealed that the wear rate was highly reduced in case of double pass FSP samples as compared to base metal and single pass FSPed composite

In the present work, Al–TiC composites were synthesized by Flux Assisted Synthesis (FAS) route. In this in situ method the TiC particles are generated from the reaction between the mixture of K2TiF6 salt and graphite in the molten aluminium. The XRD peaks have confirmed the presence of the TiC and no other undesirable intermetallics have formed after reaction. After casting the composites were extruded and then aged. All the cast, extruded and aged composites samples have exhibited significant improvement in mechanical properties in comparison with the monolithic alloy. The erosion corrosion test have been performed and found that wear resistance of the composites have significantly improved by the presence of TiC particles. Optical and Scanning electron microscopy were used for microstructural analysis and XRD was used for phase analysis. Mechanical testes were performed as per the ASTM standards.

The present work emphasizes on the synthesis of CNT-reinforced nanocrystalline AA4032 alloy powders and their consolidation by equal channel angular pressing (ECAP). Nanocrystalline AA4032 alloy reinforced with 2 wt% CNTs was produced by high-energy ball milling. The XRD analysis and TEM observation revealed the formation of nanocrystalline AA4032 alloy and uniform distribution of CNTs in the nanocrystalline matrix. The nanocomposite powders were canned in commercially pure aluminum sheath and subjected to ECAP for consolidation. More than 98% of density was achieved after four passes in route BA at the center of the can. The hardness obtained is around 218 HV5.0 after four passes in the core of alloy with 2 wt% of CNTs. Increase in hardness was significant even with minimum addition of CNTs.

Equal channel angular pressing (ECAP) is the one of the promising methods of severe plastic deformation to obtain bulk ultrafine grain structures. However, ECAP can also be used for powder consolidation. In the present study, fully dense bulk AA 4032 alloy was consolidated from nanocrystalline and microcrystalline powders. These materials were processed by ECAP until four passes at ambient temperature. It is observed that hardness and densification increased significantly with increase in number of ECAP passes. Transmission electron microscopic and scanning electron microscopic examinations evidenced that crystallite size of the nanopowders are unaltered, however a significant crystallite size reduction from around 50 µm down to submicron size is observed. Moreover, higher densification is achieved in microcrystalline powders than nano powders, whereas higher hardness in the case of nanopowders compared to microcrystalline powders.

To study intergranular corrosion (IGC) characteristics, two cast grades of duplex stainless steels, 5A and 5A stabilized with niobium, were produced in a vacuum induction melting furnace. The samples were tested under three different heat-treatment conditions that were selected using a property diagram generated through the TCFE8 database of the Thermo-Calc® software (Thermo-Calc Software, Solna, Sweden). A Feritscope FMP30® (Fischer Technology, Inc., Windsor, CT) was used to measure the ferrite phase content in the samples and compared with that specified in the property diagram. Metallurgical characteristics were analyzed through optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffractometry. Each heat-treated sample possessed a distinct texture due to the formation of various intermetallic phases in the alloy. The corrosion behavior of the samples was studied using an oxalic acid etch test. Double-loop electrochemical potentiokinetic reactivation and sulfuric acid tests were conducted on the niobium-stabilized samples, and the results demonstrated that the samples possess superior resistance to corrosion compared to those not stabilized with niobium. The addition of niobium produced a mixture of niobium compounds that suppressed the chromium depletion and reduced the degree of sensitization. This study demonstrated the potential of using niobium as a stabilizer in the duplex stainless steel alloy to considerably reduce IGC.

In the present work, AA 6351-xZrB2 [x = 0, 3, 6 and 9 weight percentage (wt.%)] in situ composites have been prepared by the reaction of mixture of K2ZrF6 and KBF4 with molten aluminium alloy at a reaction temperature of 850 °C. The in situ prepared composites were characterized by using scanning electron microscope (SEM), X-ray diffractometer (XRD), and microhardness analysis. The sliding wear properties of the prepared composite at room temperature were estimated by a pin-on-disc wear testing equipment using the composite material; the pins were machined according to standard sizes, and the tests were conducted as per the standards recommended by the ASTM G99-95a designation of different weighing percentage at room temperature. The wear characteristics of the composite in the as-cast, the solutionized and the solutionized-aged conditions were studied by conducting sliding wear test at the load of 9.81 N. The results indicated that the wear rate was decreased with an increase in the weight percentage of ZrB2 and the wear resistance was increased with an increase in the fraction of ZrB2 particulates in composite before and after heat treatment.

This technical paper covers statistical analysis of the major tribological factors affecting the dry sliding wear behaviour of Al–SiC p –brake pad system. The composite material for investigation was developed by conventional liquid casting route from Al 6082 alloy by incorporating 15% SiC p by weight. The Design of Experiments was done based on response surface method. The factors selected for investigation were temperature, load and sliding velocity keeping sliding distance constant. Experiments were conducted on high-temperature pin-on-disc wear testing equipment. Commercially available brake pads were used as the pin material. Response selected for analysis was wear rate of the AMC disc. Hardness survey, Optical microscopy and SEM were used to characterise the materials before and after the wear tests. Worn surfaces and debris were characterised using SEM to understand the wear mechanisms. ANOVA results show that temperature is the most dominant factor affecting the wear rate.

Higher productivity is registered with Flux cored arc welding (FCAW) process in many applications. Further, it combines the characteristics of shielded metal arc welding (SMAW), gas metal arc welding (GMAW), and submerged arc welding (SAW) processes. This article describes the experimental work carried out to evaluate and compare corrosion and its inhibition in SA 387 Gr.22 (2.25Cr-1Mo) steel weldments prepared by FCAW process with four different heat inputs exposed to hydrochloric acid medium at 0.1, 0.5, and 1.0 M concentrations. The parent metal, weld metal, and heat-affected zone are chosen as regions of exposure for the study carried out at 100 °C. Electrochemical polarization techniques such as Tafel line extrapolation (Tafel) and linear polarization resistance (LPR) have been used to measure the corrosion current. The role of hexamine and mixed inhibitor (thiourea + hexamine in 0.5 M HCl), each at 100 ppm concentration is studied in these experiments. Microstructural observation, hardness survey, surface characterization, and morphology using scanning electron microscope (SEM) and x-ray diffraction (XRD) have been made on samples to highlight the nature and extent of film formation. The film is found to contain Fe2Si, FeSi2, FeMn3, Fe7Mo3, Fe3O4, FeO, FeCr, AlO7Fe3SiO3, and KFe4Mn77Si19.

In the present experimental investigation, Al 6063–xTiB2 [x = 0, 5, and10 weight percentage (wt.%)] in situ composites have been prepared by the reaction of mixture of K2TiF6 and KBF4 with molten Al alloy at a reaction temperature of 850 °C. The wear characteristics of the composite in the as-cast conditions were studied by conducting abrasive wear test, and slurry erosive test. The abrasive wear behaviour of the metal matrix composites (MMCs) were investigated by varying parameters like wt.% of TiB2 particles and load. Dry Sand Rubber Wheel Abrasive Wear (as per ASTM G65 standard) testing machine was used for investigating abrasive wear behaviour. It is evident from the experiments, that in situ formed TiB2 particles offer effective coverage to the matrix and restrict the metal removal by abrasive particles. In slurry erosion, wt.% of TiB2, distance traversed and time was used as variables. The results indicate that the wear resistance of TiB2-reinforced material increased with increase in TiB2 content. The overall results reveal that TiB2 particles markedly improve the wear performance of Al 6063 alloy. The surface morphologies of the worn out surfaces were analyzed using SEM. In case of abrasive studies, the mechanism appears to be a mix-up of micro-cutting, ploughing and grain pull-out, while for erosion it is found mainly due to plastic deformation and voids.

This paper describes an experimental work carried out to evaluate and compare corrosion and its inhibition in SA 516 Gr.70 carbon steel boiler weldments made by submerged arc welding process with four different heat inputs exposed to hydrochloric acid medium at 0.1 M , 0.5 M and 1.0 M concentrations. The parent metal, weld metal and heat affected zone are chosen as regions of exposure for the study carried out at 100 °C. Electrochemical polarization techniques such as Tafel line extrapolation and linear polarization resistance have been used to measure the corrosion current. The role of hexamine and mixed inhibitor (thiourea + hexamine in 0.5 M HCl), each at 100 ppm concentration is studied in these experiments. Microstructural examination, surface characterization using scanning electron microscopy and X-ray diffraction have also been made on samples in order to highlight the nature and extent of film formation.

Welding plays an essential role in fabrication of components such as boiler drum, pipe work, heat exchangers, etc., used in power plants. Gas tungsten arc welding (GTAW) is mainly used for welding of boiler components. Pulsed GTAW is another process widely used where high quality and precision welds are required. In all arc-welding processes, the intense heat produced by the arc and the associated local heating and cooling lead to varied corrosion behavior and several metallurgical phase changes. Since the occurrence of corrosion is due to electrochemical potential gradient developed in the adjacent site of a weld metal, it is proposed to study the effects of welding on the corrosion behavior of these steels. This paper describes the experimental work carried out to evaluate and compare corrosion and its inhibition in SA 516 Gr.70 carbon steel by pulsed GTAW process in HCl medium at 0.1, 0.5, and 1.0 M concentrations. The parent metal, weld metal and heat affected zone are chosen as regions of exposure for the study made at room temperature (R.T.) and at 100 °C. Electrochemical polarization techniques such as Tafel line extrapolation (Tafel), linear polarization resistance (LPR), and ac impedance method have been used to measure the corrosion current. The role of hexamine and mixed inhibitor (thiourea + hexamine in 0.5 M HCl), each at 100 ppm concentration is studied in these experiments. Microstructural observation, surface characterization, and morphology using SEM and XRD studies have been made on samples exposed at 100 °C in order to highlight the nature and extent of film formation.

Failures of industrial boilers have been reported to be mainly due to water side corrosion and scaling. Boiler corrosion is due to highly alkaline or acidic conditions of the boiler water. The present work has been aimed at investigating the corrosion behaviour of T22 (2.25 Cr–1 Mo) boiler steel TIG weldments in neutral and alkaline media. The parent metal and weld root regions are chosen as regions of exposure for the study made at room temperature and at 100 °C. Electrochemical polarization technique such as Tafel line extrapolation (Tafel) was used to measure the corrosion current. Corrosion inhibition using thiourea at 100 ppm concentration was studied in these experiments. Micro-structural observation and surface characterization using SEM and XRD studies have been made on samples exposed at 100 °C. The results show that parent metal experiences higher corrosion rate than weld metal and thiourea as inhibitor is found unsuitable in NaOH medium.

In this paper, stabilization using zirconium and niobium was investigated to reduce the effect of intergranular corrosion (IGC) in 5A grade cast duplex stainless steel. Computational thermodynamic software was used to determine the various heat treatment temperatures according to phase precipitation. Resistance to IGC was investigated by oxalic acid etch test and double-loop electrochemical potentiokinetic reactivation (DL-EPR) technique. The surface of the specimens was observed using optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffractometry to evaluate the presence of various intermetallic phases prone to IGC. Oxalic acid etch test response has indicated the susceptibility, whereas the DL-EPR test has provided the degree of sensitization. The results revealed that zirconium-stabilized samples are more susceptible to IGC compared to the niobium samples. Earlier formation of niobium compounds led to the reduction of intergranular attack in the niobium-stabilized samples.

Pump casings made of grey cast iron (GCI) used in lignite mines for dewatering are subjected to erosive wear and fail catastrophically. An attempt was made to modify the surface of GCI by WC–Co–Cr/NiCrBSi coating using HVOF process for the application under mining conditions. Grey cast iron samples with and without WC–Co–Cr/NiCrBSi coating were subjected to slurry jet erosion tests by varying the impingent velocity and angle under two different pH conditions of 3 and 7 which pertain to the mining environment. XRD characterization was done to identify and confirm phase composition. Eroded surface morphology studies were carried by SEM on both the substrate and coating, which revealed the erosion of GCI surface, predominantly due to ploughing mechanism. In the case of WC–Co–Cr and NiCrBSi coating, at an oblique angle of impact, the material removal from the surface is by micro cutting of the matrix, ploughing, and abrasive mode mechanisms. At normal impingement, the fluctuating stress creates the cracks, which interlink each other to form lips and craters followed by material degradation through fatigue. Performance of WC–Co–Cr coating is found to be better than NiCrBSi Coating.