Residual stress analysis on machined surface in turning Stellite 6

Stellite 6 is a highly regarded engineering alloy and it possesses the wear, corrosion and heat resistance properties. Parts made of Stellite 6 are widely used in aerospace, nuclear and medical industries. Under the action of cutting forces, residual stresses may be developed during the machining of Stellite components which greatly affect the product fatigue life. The purpose of this study is to analyse the level of sub-layer residual stresses developed in the surface of a Stellite 6 workpiece when machined using optimised cutting parameters (established earlier) and using coated carbide insert as cutting tool. Experiments with turning operations have been carried out on a universal lathe machine for optimising cutting regimes on the basis of surface roughness (Ra). Optimised cutting parameters (cutting speed, feed rate and depth of cut) for nose radius 0.4 mm 0.8 mm and 1.2 mm were used for making sample to nalyse residual stress. Residual stresses on the machined surfaces were examined by X-ray diffraction methods. Values of residual stresses were plotted against the tool nose radii in graphical form which displays the magnitude of residual stresses and the effect of nose radius with optimised cutting parameters. Finally the best nose radius with optimised cutting parameters has been offered depending on the sub-layer residual stresses for Stellite machining industries.