Excellent austenitic steel and a method of manufacturing the same in cryogenic toughness in machinability and weld heat affected zone

摘要

According to the present invention, carbon (C) satisfying manganese (Mn): 15 to 35%, 23.6C + Mn ≧ 28 and 33.5C-Mn≰23 by weight%, copper (Cu): 5% or less (0 %), Chromium (Cr) satisfying 28.5C + 4.4Cr≰57 (excluding 0%), balance iron (Fe) and other inevitable impurities, Charpy impact at −196 ° C. of weld heat affected zone Provided are an austenitic steel material having a value of 41 J or more and excellent in machinability and cryogenic toughness in a weld heat affected zone, and a method for producing the same. According to the present invention, a low-cost cryogenic steel material can be obtained, a stable austenite phase is formed at a low temperature, carbide formation is effectively suppressed, and excellent in cryogenic toughness in the machinability and weld heat affected zone. Structural steel can be provided.