| 摘要 |
PURPOSE:To produce a high tensile steel material which consists of inexpensive components and has high strength and high toughness, by srolling Mn-Cr alloy steel having a specific compsn. contg. B then subjecting said steel to tempering treatment under specific conditions. CONSTITUTION:The steel contg. 0.15-0.35% C, 0.05-0.50% Si, <=0.025% P, <=0.025% S, 1.00-1.60% Mn, 0.40-1.00% Cr, satisfying <=2.20% Mn+Cr, and further contg. 0.0008-0.0025% B, and 1 or 2 kinds of 0.02-0.10% SolAl and 0.005-0..25% Ti and the balance Fe and unavoidable impurities, is used as a blank material, and after rolling, said steel is subjected to a tempering treatment at 480-550 deg.C, whereby a high tensil steel material having the strength of about >=80kg/mm.<2> yield point and about >=90kg/mm.<2> tensile strength is obtained. Said steel material is improved in strength and toughness by forming a solid soln. of B in the Mn-Cr steel and tempering the same at lower temps. |
