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本文通过渗碳后冷处理和改变淬火加热温度两种方法,研完了18Cr2Ni4WA钢渗层中的残余奥氏体(γ_R)对硬度、静弯强度、冲击韧性、耐磨性以及尺寸变化的影响。试验证明:18Cr2Ni4WA渗碳空冷后,渗层存在大量的γ_R(68～75%);γ_R对室温停留的陈化稳定不敏感;冷处理过程中未发现明显的恒温马氏体转变;渗层中γ_R量愈多,静弯强度和冲击韧性愈高;当表层中γ_R量稍低于42%时,其耐磨性最佳。渗碳后高温回火再800℃加热淬火后,性能比直接冷处理的显著改善。此外,本文尝试了通过测量薄壁圆筒穿透渗碳试样的轴向伸长率,来予测实际渗碳零件表层的残余轴向压应力。
In this paper, the effects of retained austenite (γ_R) on the hardness, static bending strength, impact toughness, wear resistance and dimensional change of 18Cr2Ni4WA steel infiltrated layer were studied by two methods: cold treatment after carburizing and changing heating temperature. The results showed that there was a large amount of γ_R (68-75%) in the infiltrated layer after carburizing air cooling in 18Cr2Ni4WA. Γ_R was not sensitive to the aging stability at room temperature. No significant thermostatic martensitic transformation was observed during the cold treatment. Γ_R The more the amount, the higher the static bending strength and the impact toughness; and when the amount of γ_R in the surface layer is slightly lower than 42%, the wear resistance is the best. After carburizing high temperature tempering and then quenching 800 ℃, the performance is significantly improved than the direct cold treatment. In addition, this paper attempts to measure the residual axial compressive stress on the surface of the actual carburized parts by measuring the axial elongation of the thin-walled cylinder penetrating carburized specimens.