The effect of aging on machinability of 15Cr–5Ni precipitation hardened stainless steel

This study is an attempt to correlate the microstructure and mechanical properties of commercial 15Cr–5Ni precipitation-hardening stainless steel in different aging regimes such as solution treated (Condition A), over-aged (Condition H1150-M) and peak-aged (Condition H900) with their machinability behavior. Aging was done on 15Cr–5Ni precipitation-hardenable stainless steel samples in a temperature range of 480–760 °C. Over aging of the above material resulted in an improvement of ductility and a substantial reduction in tensile strength. Heat treated samples were machined in order to study the effects of machining parameters on machinability aspects such as cutting forces, surface roughness, chip morphology and tool wear. Experimental investigation revealed a strong correlation between the rate of cooling after aging and cutting forces. Air cooled samples exhibited higher cutting forces compared to furnace cooled samples. The surface finish is found to be improved for H900 air cooled sample, which has higher hardness than that of as received sample and H1150-M condition.