Mechanical Properties of Carburized Austenitic Stainless Steels as Related to Microstructure

摘要

Results are presented for tests carried out on tube tensile specimens of four austenitic stainless steels (AISI Types 304, 316, 321, and 347) carburized in a methane-hydrogen mixture for 1 hr each at 870C (1600F), 925C (1700F), 980C (1800F), and 1040C (1900F). Specimens were carburized on both the external and internal surfaces. The carburized case encompasses two zones: (1) a dark etching area of carbide (Fe.Cr)7C3 and austenite, and (2) a heavily carburized grain boundary area, also (Fe.Cr)7C3, that precedes the bulk carburization area. Both zones are quite brittle and develop cracks under a tensile load. The uncarburized austenite acts in a crack-blunting capacity. (Author)