AUSTENITE STAINLESS STEEL HAVING GOOD WELDABILITY AND RESISTANCE TO STRESS CORROSION CRACKING IN HIGH TEMPERATURE PURE WATER

摘要

PURPOSE:To improve stainless steel in weldability and resistance to stress corrosion cracking in high temperature pure water, steel composition is controlled in reference to a ratio of some selected alloy elements such as Cr, Ni, Mo, Nb, Ta, etc. CONSTITUTION:''Intergrain'' strain stress corrosion cracks occur, when austenite stainless steel is bent into double-U-letter-shape in high temperature pure water. A composition that overcomes this difficulty comprises: C:up to 0.04%, Si:up to 2%, Mn:up to 2%, Cr:16 to 22%, Ni:9 to 18%, Mo:1 to 4%, N:up to 1/ (150XC%)2%, Nb and/or Ta being in a range such that Nb+1/2Ta becomes 12XC% to 1%, the balance iron and unavoidable impurities. This steel is molten produced in an electric furnace, wherein alloy components thereof are adjusted, bloomed, that-and cold-treated to be made into steel material having desired shape and size and heat treated at a temperature of higher than 1,000 deg.C. The stainless steel thus formed, having complete austenitic structure with extremely fine grains, exhibits remarkably improved resistance to stress corrosion cracking in high temperature water.