Compound low carbon and high sulfur free-cutting steel with Sn and Sb

Cutting tests and high-temperature thermo-ductility experiment were carried out on low-carbon and high-sulfur free-cutting steel with low contents of tin and antimony or bismuth. The results show that the wear at the tool flank face for machining of experimental steel is very small after long-time and high-speed machining tests. The machinability of the new steel is significantly better than that of SAE1215. The thermo-ductility of the steel with Sn and Sb is poor within the range from 750 to 950℃ but good from 1050 to 1300℃. It is also showed by SEM and EDS that tin and antimony exist at grain boundaries in the steel, and in or around MnS inclusions. Most of bismuth element are attached to MnS inclusions, some are scattered in the steel matrix. The shapes of MnS inclusions are mainly spherical and spindle.