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球墨铸铁曲轴应具有很高的弯扭疲劳强度、耐磨性、一定的循环韧性和低的应力集中敏感性。但是球墨铸铁的铸造组织因铁素体含量波动于15～40％之间而不能满足上述要求。这个问题可以用曲轴轴颈感应淬火来解决。球墨铸铁淬火的效果主要取决于α→γ转变的完成情况和奥氏体的碳饱和度。铁素体向奥氏体的转变完成情况首先决定于感应加热速度。早先的研究得出,为了在以50～450℃/秒的速度加热球墨铸铁时完成奥氏体化,必须使基体铸造组织中的铁素体不高于30％。研究球墨铸铁(铁素体含量在40％以下)
Ductile iron crankshaft should have a high bending and torsional fatigue strength, wear resistance, a certain degree of cycle toughness and low stress concentration sensitivity. However, the ductile iron casting structure due to ferrite content fluctuations between 15 ~ 40% and can not meet the above requirements. This problem can be solved by crankshaft journal induction hardening. The effect of ductile iron quenching depends mainly on the completion of α → γ transformation and austenite carbon saturation. The transformation of ferrite to austenite is primarily determined by the induction heating rate. Earlier studies have found that in order to accomplish austenitization when the ductile iron is heated at a temperature of 50 to 450 ° C / sec, it is necessary to make the ferrite in the matrix cast structure not more than 30%. Research ductile iron (ferrite content of 40% or less)