ENHANCED MACHINABILITY AND OXIDATION RESISTANCE OF P M STEELS USING MODIFIED MNS ADDITIONS/

The usefulness of manganese sulfide as a machinability-enhancing addit ive, especially for powder metal parts, is well known. The residual po re structure generally rouses limited tool life and restricts the use of liquid coolants, Here, he results of a study on improved machinabil ity of steel via additives bossed on manganese sulfide with controlled additions of iron are presented, The shortcomings of the pure additiv e are reviewed, including an explanation of physical and chemical aspe cts. For the new additive, the role of oxygen content, particle size d istribution and the iron are analyzed, Results ore presented which sho w that the modified additive provides enhanced machinability and impro ved oxidation resistance compared to pure MnS.