| 摘要 |
PURPOSE:To obtain a spheroidal graphite cast iron provided with high strength, toughness and wear resistance by subjecting the spheroidal graphite cast iron to an imperfect austemper treatment under an adequate condition then to a subzero treatment to harden the cast iron into a perfect state then tempering the hardened cast iron at a low temp. CONSTITUTION:A spheroidal graphite cast iron is heated and is held for 0.5- 3hr at 850-950 deg.C and is thus austenitized and then it is quickly dipped in a salt bath kept at 210-430 deg.C and is held until the residual austenite attains 5- 80vol%, thereafter, the cast iron is cooled down to a room temp. Such cast iron is subjected to a subzero treatment for 10-120min at -30--196 deg.C to convert thoroughly the residual austenite to martensite thereby hardening the cast iron in a perfect state. Such cast iron is subjected to low temp. tempering for 1- 5hr at 150-200 deg.C. High strength, toughness and wear resistance are thus provided in combination to the spheroidal graphite cast iron. |
