Free-Machining Powder Metallurgy Steel Articles and Method of Making Same

摘要

A small diameter, elongated steel article, comprising fully consolidated, prealloyed metal powder is disclosed. The consolidated metal powder has a microstructure that has a substantially uniform distribution of fine grains having a grain size of not larger than about 9 when determined in accordance with ASTM Standard Specification E 112. The microstructure of the consolidated metal powder is further characterized by having a plurality of substantially spheroidal carbides uniformly distributed throughout the consolidated metal powder that are not greater than about 6 microns in major dimension and a plurality of sulfides uniformly distributed throughout the consolidated metal powder wherein the sulfides are not greater than about 2 microns in major dimension. A process for making the elongated steel article is also disclosed.