Means to Improve Machinability of Sintered Stainless Steel
Austenitic stainless steels are difficult to machine, and if a significant amount of machining is required in an application, one often has no choice but to use a sulfide containing grade, such as 303L, or 316L admixed with MnS. The presence of sulfides in an austenitic stainless steel, however, lowers its corrosion resistance significantly. Addition of a small amount of Sn and Cu has been reported in the literature to significantly improve corrosion resistance of austenitic stainless steels, including that of the sulfide containing grade. Addition of Sn and Cu is also reported to have a favorable influence on the machinability of sulfide free grades of P/M austenitic stainless steels. This study evaluates the machinability and corrosion resistance of the standard grades, 303L and 304L, along with their Sn and Cu modified versions, 303LSC and 304LSC, and a Cu modified version of 303L, called 303LCu. In this study all sintering was carried out under conditions that are known to be ‘optimal’ from the corrosion resistance point of view. Machinability was determined by the use of a drilling test.