Studies of cryogenic cooling on the drilling process of super duplex stainless steel

Abstract

In this present research work, drilling operation is performed in super duplex stainless steel (SDSS 2507) material. This material has major application in the area which requires high mechanical strength and corrosive environments such as seawater equipment, desalination plant, oil and gas industries, heat exchangers, brine and alkaline solution. The tool material was chosen as solid carbide twist drill. The drilling operation is performing under i) uncoated tool under (cryogenic, wet and dry) cutting conditions ii) coated tool by PVD process by means of multi-layer (AlCrN+TiN) coating under (cryogenic and dry) cutting conditions. The machining parameters are chosen based on the literature survey for all the cutting conditions. The levels of cutting velocities are (40, 50 and 60 m/min) and their corresponding feed rates are (0.03, 0.05 and 0.07 mm/rev) and constant depth of 20 mm. The measuring output parameters are thrust force, torque, temperature, surface roughness, tool wear, microstructural analysis, microhardness, chip thickness, chip width and chip morphology were analysed and compared for all the cutting conditions.The drilling of material like SDSS 2507 is difficult due to their properties such as low thermal conductivity, high toughness and high work hardening during machining. This causes maximum tool wear, which affects the tool life and drilled hole surface finish. More the tool wear also causes high frictional forces and cutting temperature. To overcome and control the cutting temperature during the machining operation, metal cutting industries uses various types of cutting fluids. But till now, most of the metal cutting industries make use of a conventional type of emulsion oil-based cutting fluids to remove the heat from cutting zone. At the same time, heat-carrying capacities of the conventional type cutting fluid are not effective, which lead to rapid tool wear. newline