论文部分内容阅读
本文研究了渗碳后热处理工艺对18Cr2Ni4WA渗碳钢组织和性能的影响。结果表明:渗碳后油冷并于Ac_1～Ac_3之间淬火,试件心部得到细小的针状F+M复合组织;渗碳后炉冷并于Ac_1～Ac_3之间淬火,心部得到细小的颗粒状F+M复合组织。当淬火温度高于Ac_3时,渗碳后油冷或炉冷试件心部和表层均为粗大的M+A_R。渗碳后油冷再淬火的整体冲击韧性高于渗碳后炉冷再淬火者,特别是在接近Ac_1再淬火时差别更大。随淬火温度降低,炉冷者的整体冲击韧性随之下降;而油冷者变化不明显,并且比渗碳后二次淬火者稍高。试件渗碳后无论经油冷还是炉冷,心部硬度均随淬火温度的降低而下降,而表层硬度先增后降。建议此钢的渗碳热处理工艺采用渗碳后快冷+较低温度下的加热淬火,这样可在保证表层具有高硬度的前提下心部具有较高的韧性,以满足零件服役条件对性能的要求。
This paper studies the carburizing heat treatment process on the 18Cr2Ni4WA carburizing steel microstructure and properties. The results show that after carburizing, the oil is oil-cooled and quenched between Ac_1 and Ac_3. The fine needle-like F + M composite structure is obtained in the heart of the specimen. After carburizing, the furnace is cold and quenched between Ac_1 and Ac_3. Of granular F + M composite tissue. When the quenching temperature is higher than Ac_3, the carburized oil-cooled or furnace-cooled specimens are coarse M + A_R at the heart and the surface. The overall impact toughness of oil-cooled re-quench after carburizing is higher than that of re-quench after carburizing, especially when it is close to Ac_1. As the quenching temperature decreases, the overall impact toughness of the furnace cooling decreases; while the oil cooling changes are not obvious, and slightly higher than the second quench after carburizing. After carburizing, the hardness of core decreases with the decrease of quenching temperature, and the surface hardness first increases and then decreases after carburizing. It is suggested that the carburizing heat treatment process of this steel adopt quick cooling after carburizing and heating quenching at a lower temperature so as to ensure the toughness of the core under the condition that the surface layer has high hardness so as to meet the performance requirements of parts service conditions .