STUDY ON THE MACHINABILITY OF RESULFURIZED COMPOSITE FREE-CUTTING STEELS

The machinability of S, S-Ca, S-RE, and S-RE-Ca system resulfurized co mposite free-cutting steels were investigated, where RE is rare earths , mostly cerium, The experimental results showed that in the low cutti ng speed range (less than or equal to 35 m/min), the S-RE system free- cutting steel had better machinability than the others and that the S- RE-Ca system free-cutting steel exhibited the best machinability at hi gh cutting speeds, A protective layer capable of preventing diffusion wear was formed on the rake face of a P30 tool when S-RE-Ca system fre e-cutting steel was machined in the cutting speed range of 120 to 160 m/min.