Austenitic - ferritic chromium-nickel-nitrogen steels - for chemical industry esp food, paper and fermentation industries

摘要

Corrosion- and heat-resistant austenitic Cr-Ni-N steel, used in mfr. of articles resistant to organic acids contain 0.005-0.065 (0.05)% C, 0.1-1 (0.3-0.6) % Si, 0.5-4 (0.5-2)% Mn, 22.5-28 (23-27)% Cr, 3.5-8 (4-6)% Ni, 0.08-0.4 (0.1-0.3)%N, bal. Fe, and at a ferrite content of 30-70%, are brought to a 0.2% yield strength 75 kp/mm2, with simultaneously good notch impact strength, by primary deformation at 1155 degrees C and further deformation at 1000 to 800 degrees C. Used in the chemical industry, esp. for component parts used in fermentation, food, pharmaceutical and paper industries. Steel alloys resist solns. contg. small amounts of Cl. Thus resistance to stress corrosion in 0.1-1% chloride soln. at 150-250 degrees C is higher than in standard austenitic Cr-Ni steels. 475 degrees C-embrittlement is suppressed and sigma-phase embrittlement at 700 degrees C is very slight.