Surface integrity of hard-turned M50 steel

The purpose of this paper is to examine how the surface integrity of M50 steels is affected by hard turning. Tests were conducted on a lathe using different tools and depth of cut. The surface was evaluated in terms of residual stress, surface roughness and microstructure analysis. The tests showed that hard turning provides good surface integrity. The effect of tool parameters and depth of cut on residual stress was investigated in order to find how the residual stress could be altered. It was found that effective rake angle and tool nose radius both affected the residual stress generated. The surface roughness of the hard-turned test samples followed the theoretically calculated values. The surface of the test samples showed no alteration to the microstructure. On the basis of the results it can be concluded that hard turning of M50 steel is a suitable manufacturing process. One possible application for this process is the manufacturing of a main shaft bearing for an aero-engine.