AUSTENITIC STAINLESS STEEL THICK PLATE AND BAR FOR CRYOGENIC USE EXCELLENT IN TOUGHNESS

摘要

PURPOSE: To provide an austenitic stainless steel thick plate and bar for cryogenic use excellent in toughness. ;CONSTITUTION: The austenitic stainless steel thick plate and bar having a compsn. contg. ≤0.04% C, 0.01 to 2.0% Si, 1 to 8% Mn, 15 to 27% Cr, 10 to 20% Ni, 0.01 to 0.2% Nb, 0.001 to 0.10% Al and 0.1 to 0.5% N and contg., at need, one or more kinds of 0.5 to 3% Mo and 0.0005 to 0.01% Ca, and the balance iron with inevitable impurities and having ≥40mm thickness or diameter are produced. In the thick plate having a low cooling rate, Nb carbon nitrides finely precipitated in the grains at the initial stage of cooling in soln. heat treatment function as the precipitating nucleus of Cr carbon nitrides precipitated by the subsequent cooling, so that the precipitation of the Cr carbon nitrides into the grain boundaries can be reduced to secure excellent toughness at a very low temp.;COPYRIGHT: (C)1995,JPO