| 摘要 |
PURPOSE:To obtain case hardening steel which prevents the formation of coarse grains of austenite crystals by subjecting steel contg. specific ratios of C, Si, Mn, sol.Al, Cr, N to heating and finish rolling at specific temp. then to cooling under specific conditions. CONSTITUTION:The steel contg. 0.01-0.30% C, 0.03-0.50% Si, 0.30-1.80% Mn, 0.015-0.060% sol.Al, 0.30-1.80% Cr, 0.006-0.025% N and if necessary, contg. 1 or >=2 kinds among 0.04-0.40% S, 0.05-0.40% Pb, 0.005-0.20% Bi, 0.005- 0.20% Te, 0.001-0.020% Ca, and consisting of the balance iron and unavoidable impurities is heated to >=1,000 deg.C. After such steel is subjected to finish rolling at >=900 deg.C, it is held for 5-120min in a 700-600 deg.C temp. region during the course of cooling. |
