| 摘要 |
PURPOSE:To produce a shaft member having excellent strength and wear resistance by subjecting a steel material contg. a small amt. of V, Cr, etc. to a heat treatment under specific conditions then to a soft nitriding treatment. CONSTITUTION:A steel material contg. 0.15-0.4% C, <0.50% Si, 0.50-1.50% Mn, 1.00-3.00% Cr, 0.05-0.15% V, 0.006-0.02% N is heated to 1,000-1,250 deg.C and is hot-rolled to form a bar material. The rolled steel material is subjected to regulated cooling at a cooling rate of 0.2-4.0 deg.C/sec down to 800-500 deg.C and is thereafter air-cooled. Carbonitride of V is precipitated and bainite structure is precipitated by said heat treatment. The material is in succession machined to a shaft material which is then subjected to a gaseous soft nitriding treatment. The material may be heated and held for 5-60min at 900-1,100 deg.C after hot- rolling and subjected to regulated cooling. |
