Free machining austenitic stainless steel having low nitrogen contents

摘要

PURPOSE: To manufacture a free machining austenitic stainless steel having low nitrogen contents by inhibiting precipitation of Cr-nitride at phase transition between austenite and MnS or austenite and ferrite. CONSTITUTION: The free machining austenitic stainless steel having low nitrogen contents comprises C 0.15 wt.% or less, Si 1.0 wt.% or less, Mn 1.0-3.5 wt.%, S 0.15-0.40 wt.%, Cr 16-19 wt.%, Ni 8-14 wt.%, Mo 2.5 wt.% or less, Cu 4 wt.% or less, N 0.015 wt.% or less, a balance of Fe and other inevitable impurities, wherein Cr/N ratio is 1067 to 19000, Mn/S ratio is higher than 4.5, and oxygen content in the free machining austenitic stainless steel is 0.007 to 0.11 wt.%.