Study on the Machinability of Free Cutting Non-Lead Austenitic Stainless Steels

In this paper, a new non-lead machinable austenitic stainless steel was investigated. The metallurgical properties, machinability and mechanical properties of the developed alloy were compared with those of the conventional austenitic stainless steel 321. The results have shown that the presence of machinable additives, such as sulfur, copper and bismuth, etc. contributes to the improvement of the machinability of austenitic stainless steel, because the inclusions are something like internal notches causing crack nucleation and facilitating rupture. Bismuth has a distinct advantage over lead. The machinability of the austenitic stainless steels with free-cutting additives is much better than that of austenitic stainless steel 321. The mechanical properties of the free cutting austenitic stainless steel are similar to those of 321 although the former are slightly lower than those of the latter.