The effect of machining parameters on surface integrity and fatigue performance of 42CrMo4 + QT high-strength steel

This study investigates how machining parameters affect surface integrity and fatigue performance in 42CrMo4 + QT steel. Nine turning setups were tested to evaluate surface roughness, residual stresses, and fatigue strength. Fatigue testing under fully reversed loading (R = –1) at ∼150 Hz revealed that the best fatigue performance occurred in the setup with a cutting speed of 100 m/min, feed rate of 0.1 mm/min, tool nose radius of 0.4 mm, 0.3 mm total finishing depth (over three cuts), and coolant applied. Cutting speed showed the clearest benefit, while other parameters had less predictable effects. Surface roughness did not consistently correlate with fatigue life. Overall, selected machining parameters strongly influence fatigue behavior, though roughness and residual stresses alone do not fully explain the performance trends observed.