Machinability of 13%Cr Stainless Steel Included Titanium Carbo-Sulfide

Lead (Pb) is one of the most effective alloying elements to improve the machinability of steels. However the movement of eliminating Pb contents is recently increasing because of reducing environmental impact. Therefore new types of free cutting steels without Pb are strongly required. Ti4C2S2 is one of the promissing candidates of free cutting elements. However the mechanism of improvement in machinability by Ti4C2S2 has not been confirmed yet. In this study we investgated the effect of Ti4C2S2 in 13 % Cr stainless steels. Ti4C2S2 had notch effect like other sulfides such as MnS. Thereby chip breakability was improved. Ti4C2S2 also had tool-protecting effect by forming stable adhesion. On the other hand Ti4C2S2 was not shown remarkable lubricant effect as Pb. The improvement of machinability in 13 mass%Cr ferritic stainless steels by including Ti4C2S2 attribute to the chip breakability and restraint of the tool-wear by forming stable adhesion.