Enhanced machinability and oxidation resistance of P/M steels using modified MnS additions

摘要

The usefulness of manganese sulfide as a machinability-enhancing additive, especially for powder metal parts, is well known. The residual pore structure generally causes limited tool life and restricts the use of liquid coolants. Here, the results of a study on improved machinability of steel via additives based on manganese sulfide with controlled additions of iron are presented. The shortcomings of the pure additive are reviewed, including an explanation of physical and chemical aspects. For thenew additive, the role of oxygen content, particle size distribution and the iron are analyzed. Results are presented which show that the modified additive provides enhanced machinability and improved oxidation resistance compared to pure MnS.