Hassan Jayaraj Amarendra

Slurry Erosion Response of Heat Treated 13Cr-4Ni Martensitic Stainless Steel

In the present work, effect of various heat treatments on slurry erosion behavior of 13Cr-4Ni martensitic stainless steel (MSS) at different impingement angles has been studied. The as-received cast bars of MSS were given various heat treatments. These heat treatments involved the austenitization of cast steel at temperatures of 950° C, 1000° C and 1050° C for different soaking durations of 2, 4 and 6 h at each temperature. This was followed by oil quenching then tempering for 1 h at a 600° C air cooled. Heat treated MSS samples were characterized for microstructure and mechanical properties viz. hardness, ductility (% elongation), tensile strength (UTS), and toughness. For wear characterization, slurry erosion tests were conducted at different impingement angles for as-received cast and heat treated samples. The heat treated MSS shows approximately 34% lesser weight loss as compared to as-received cast MSS. Increase in toughness of heat treated samples is found to be responsible for the improved slurry erosion resistance. Impingement angle close to 0° showed least wear loss.

Cavitation and Slurry Erosion of Aluminum in the Slurry Pot Tester

In harnessing clean and renewable energy sources water turbines represent a significant portion of the power generation worldwide. Because of erosion, repair and maintenance of hydraulic turbines is a difficult problem. Material removal in hydraulic turbine components may occur either by particle erosion or cavitation erosion or by their combined action. Many ASTM standard and non standard test rigs are aimed at specific tests, like solid particle erosion, cavitation erosion. To simulate the real conditions in a laboratory setup, a novel method is employed to combine the effect of cavitation erosion and slurry erosion in the slurry pot tester. Triangular prismatic cavitation inducers are used in the conventional slurry pot tester. The aluminum test specimens are investigated in the slurry pot tester. A wide variation in material loss was noted under different exposure conditions. The maximum material loss is ascribed to combined effects of solid particle erosion and cavitation erosion.

Microstructural Investigation and Characterization of Bulk Brass Melted by Conventional and Microwave Processing Methods

Microwave processing of bulk metallic materials is an emerging area. In the present work, brass in bulk form is melted in a modified domestic microwave oven operating at 2.45 GHz frequency. As-received and the as-cast brass are subjected to metallurgical and mechanical characterization. Specimens’ surface morphology is studied under Scanning Electron Microscope (SEM). X-Ray Diffraction (XRD) pattern shows the presence of copper oxides phase in both cast brass. Average tensile strength of brass melted using microwave oven is found higher when compared with brass melted in muffle furnace. Hardness of the as-cast brass is found to be higher than the as-received brass. However, brass cast by microwave irradiation exhibits around 2 % higher hardness than the brass cast by conventional heating. Microwave melting of brass consumed nearly six times less time compared to conventional melting.

Effect of Deposition Parameters & Molybdenum Percentage on Nickel-Molybdenum Alloy Coatings

The use of Potassium-phosphate baths for the alloy deposition of Nickel–Molybdenum is recently proved equally good as Sodium-citrate baths. The coatings so obtained from Potassium-phosphate baths were examined for atomic weight percentage of Molybdenum. The variation in weight percentage of Molybdenum was obtained by varying different plating parameters like - molar ratio, current density range, and potential range. The observed co-deposited Molybdenum Atomic percentage variation in alloy was investigated for grain size, porosity in structure and surface roughness. The results revel that Molybdenum Atomic percentage in the Nickel–Molybdenum alloy has effect on porosity and surface roughness. It was also found that root mean square value of surface roughness was not only affected by the Molybdenum Atomic percentage but also by potential at relaxation time (TOFF) potential.