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Selective laser melting (SLM) has received huge attention recently by the research community due to feasibility of realization of tailored intricate metallic structures having applications in biomedical, aviation and energy industries. SLM of Ti6Al4 V is found to be one of the most demandable and potential area. Present work is aimed for critical review of noteworthy contributions in terms of SLM process parameters, defects and various post processing techniques considered by various researchers. Proper selection of process parameters can arrest the tendency of defect generation and appropriate post treatment results in improvement in mechanical behavior in comparison with as-built SLMed Ti6Al4 V components. Efforts have been made to identify correlations between SLM parameters, specially scan speed, laser power, hatch spacing and layer thickness, with prominent defects. Different post processing approaches considered by important research studies have been extensively analyzed and their impact on defects and mechanical behavior especially fatigue performance and biocompatibility of SLM-fabricated Ti6Al4 V alloy is revealed. Many remedies have been identified in the form of optimization of process parameters and post processing techniques. The outcomes of work have clearly facilitated in developing a better scientific understanding of SLMed Ti6Al4V alloy and have also opened many dimensions for future investigations.

Recently microwave assisted materials processing earningvoguedue to inherent gains in terms of time and energy efficiency, substantially reduced process cycle time, revamp mechanical properties, and beneath environmental hazards. During processing of materials through microwaves, equally electric and magnetic energy is linearly transferred within materials via interfacing interaction between molecules. Microwave processing is pertinent to vast variety of materials including metal matrix composites (MMC), fibre reinforced polymer (FRP), alloys, ceramics, metals, pulverize metallurgy, metal coating/ cladding etc. This paper presents several key fundamentals of microwaves and concisely depicts the studied microwave materials interaction mechanism. Microwave energy are extensively used, notably in the areas like coating, glazing and cladding on various metallic substrate materials like mild steel, and different grades of stainless steel (SS-316, SS-316L, SS-304, AISI-420) etc. Microwave applications in improving the surface properties of metallic materials are briefly reviewed in this paper.

Al-Zn-Cu alloy Al7050-T7451 is used extensively in the aero-space industries. Aerospace components are generally joined using riveting, which increases the overall weight of aeroplane. In this context, friction stir welding (FSW) process could be a potential solution. In this research work, Al7050-T7451 specimens were welded by FSW, using different parametric combinations of tool rotation and welding speed. The friction-stir weldments were further subjected to deep cryogenic treatment. Microstructure and some mechanical properties of the weldments were investigated for both cryo-treated and untreated conditions. It was observed that the grain size of the nugget zone (NZ) got refined after the cryogenic treatment. It was also revealed that microhardness was more in case of cryo-treated joints as compared to untreated. Micro-hardness of the NZ was observed to be highest due to formation of finer grains after exposure to cryogenic temperature. Deep cryogenic treatment has also improved impact toughness and tensile properties such as yield strength and % elongation of the FSW joints.

In the present work, Cr3C2-25NiCr and WC-10Co-4Cr coatings were deposited on AISI304 turbine steel using HVOF-spray process. Performance of these HVOF-spray coated and bare turbines steel was investigated under varied conditions of slurry erosion. Slurry erosion resistance was premeditated by using a laboratory developed slurry erosion test rig. Phases, microstructure and eroded surface were characterized using SEM and XRD analysis. It was observed that HVOF-spray WC-10Co-4Cr coating had shown remarkable erosion resistant feature due to the presence of dense, well bonded structure along with higher hardness followed by Cr3C2-25NiCr coated steel and AISI 304 bare turbine steel. It was observed that under erosion condition, bare steel and Cr3C2-25NiCr coating exhibited ductile followed by brittle mechanisms respectively. Similarly degradation mechanism for WC-10Co-4Cr coating exhibited mainly ductile behaviour

In research work variation of cutting performance with pulse on time, pulse off time, wire type, and peak current were experimentally investigated in wire electric discharge machining (WEDM) process. Soft brass wire and zinc coated diffused wire with 0.25 mm diameter and Die tool steel H-13 with 155 mm× 70 mm×14 mm dimensions were used as tool and work materials in the experiments. Surface roughness and material removal rate (MRR) were considered as performance output in this study. Taguchi method was used for designing the experiments and optimal combination of WEDM parameters for proper machining of Die tool steel (H-13) to achieve better surface finish and material removal rate. In addition the most significant cutting parameter is determined by using analysis of variance (ANOVA). Keywords Machining, Process Parameters, Material removal rate, Surface roughness, Taguchi method

Erosion due to slurry has an indispensable effect on the lifespan and operating efficiency of hydro machine components. To mitigate this effect, laser cladding may prove as a cost-effective choice to improve the surface properties of various hydro machine components. In this research work, a laser cladding of Colmonoy-6 + 50%WC powder on the surface of SS410 steel was deposited using high-power diode laser at optimized levels of operating parameters. The deposited coating was characterized with regard to different mechanical and metallurgical properties. The effect of various factors such as slurry concentration, erodent particle size, impact velocity, and impact angle on slurry erosion behavior of uncoated and laser cladded substrate was analyzed. The Colmonoy-6 + 50%WC cladded specimens exhibited significantly better slurry erosion resistance in comparison with uncoated SS410 steel specimens under all slurry erosion conditions. Impact velocity was observed to be a maximum contributor to slurry erosion, followed by impact angle, average particle size and slurry concentration. The SEM micrographs of eroded cladded surfaces showed signatures of lip formation & fracture sites, micro-cutting, ploughing, and wear marks at a shallow impact angle in Colmonoy-6 pool, however, for normal impact, the existence of cracks in WC particles were observed.

Hydrophobic materials have the potential to replace the existing surface modification materials to combat the problem of cavitation erosion (CE), owing to their various capabilities like self-cleaning, anti-corrosion, anti-fogging, anti-icing, anti-fouling, and drag-reduction. Polytetrafluoroethylene (PTFE) as a hydrophobic material exhibits specific combination of properties such as low friction coefficient, chemically neutral, good impact strength and considerable thermal firmness, that allow PTFE to be used in a wide range of applications. Therefore, in this work, an effort has been made to explore the effect of thickness of hydrophobic PTFE coatings on CE of the hydro-machinery SS410 steel. Hydrophobic PTFE coatings with three variable thicknesses have been prepared on the hydro-machinery SS410 steel using sintering process. Using high-velocity submerged water jet cavitation erosion test rig, CE behaviour of PTFE coated and bare SS410 steel was evaluated under various combinations of operating parameters: namely jet velocity, stand-off distance (SOD), and impact angle. Contact angle was reported to be increased with the decrease in the thickness of PTFE layer, which may be due to the increased surface roughness of PTFE layer with decrease in thickness. CE resistance of PTFE coated material with a maximum thickness of 121 μm, was found to be highest for all the combinations of operating parameters, which may be attributed to its lowest fracture toughness and better cushioning effect. Further, it was observed that CE of the coated and SS410 steel was found to be maximum at the chosen maximum velocity, normal impact angle, and intermediate SOD. The signatures of pits with circular and elongated morphology were observed for normal and shallow impact angles, respectively. In case of lowest PTFE layer thickness, overlapped pits with relatively higher depth were observed, which might be responsible for higher CE of the same amongst all the PTFE coatings.

Slurry erosion behaviour of high velocity oxy fuel (HVOF) and high velocity oxy liquid fuel (HVOLF) sprayed coatings on hydraulic turbine material (i.e. CA6NM steel) was investigated at different levels of various parameters. The 50 % (WC–Co–Cr) and 50 % (Ni–Cr–B–Si) coating powder was deposited on CA6NM steel samples by HVOF and HVOLF thermal spraying techniques. Erosion tests were conducted on self-made erosion test rig with various factors as explained in the "experimentation" section. Coated and uncoated samples of CA6NM steel were investigated by following a design of experiments based on the L9 Taguchi technique, which was used to obtain the data of erosion test in a controlled way. Four parameters used in L9 experiment were velocity, impact angle, slurry concentration and average particle size. The study revealed that the velocity, impact angle and slurry concentration were most significant among various parameters, influencing the wear rate of the coatings. The average particle size did not show any significant effect on both the coatings. In comparison, coated samples showed approximately two times better results in erosion resistance than uncoated samples. Scanning electron microscopy of eroded surface showed different mechanisms of erosion on different samples under various conditions.

The present work describes the application of High-Velocity oxy-fuel spray process with Ni-20Cr2O3 powder deposition on the various pipeline steels namely SS 202, SS 304, and mild steel. The slurry erosion wear tests were performed on coated and uncoated steels by considering slurry concentration, impact velocity, and erosion time as input parameters. It was concluded that for all materials, rpm (impact velocity of erodent's) influences on erosion wear the most. It was also noticed that the erosion resistance has been improved with SS 202 steel followed by to SS 304 and mild steel. Further, Ni-20Cr2O3 coatings showed maximum enhancement in slurry wear resistance of mild steel, followed by SS 304 steel and SS 202 steel.