深冷处理对18Cr2Ni2MoNbA钢耐磨性的影响

Effect of deep cryogenic treatment on wear resistance of 18Cr2Ni2MoNbA steel

使用正交试验对18Cr2Ni2MoNbA钢渗碳钢深冷处理工艺参数进行筛选优化,分析深冷处理时间、低温回火温度和时间对试样耐磨性的影响,并对试样磨痕形貌、显微组织、残留奥氏体以及显微硬度进行分析。研究表明,18Cr2Ni2MoNbA钢渗碳淬火后的-196℃深冷工艺参数对磨损量影响的显著性排序为:深冷处理时间>低温回火时间>低温回火温度。深冷处理能够有效增加试样的耐磨性,在深冷温度-196℃,深冷处理时间1 h,低温回火温度120℃,低温回火时间2 h的工艺下试样磨损量最小,与未深冷时相比减少46.67%,磨损机制变为磨粒磨损与氧化磨损。经过深冷处理后渗碳层的碳化物沿晶界析出,同时有小颗粒碳化物在基体上弥散析出。深冷处理能够降低钢的残留奥氏体含量,增加马氏体含量,使表层渗碳层的显微硬度增加,从而改善18Cr2Ni2MoNbA钢的耐磨性。

Deep cryogenic treatment process parameters of 18 Cr2 Ni2 MoNbA carburized steel were selected and optimized by using orthogonal test. The effect of cryogenic time, low temperature tempering temperature and low temperature tempering time on the wear resistance of the steel was studied, and the wear scar morphology, microstructure, retained austenite and microhardness were analyzed. The results show that when cryogenic treated at-196 ℃ after carburizing and quenching, the influence of cryogenic parameters on the wear amount of the 18 Cr2 Ni2 MoNbA steel is in the following order of significance as cryogenic time, low temperature tempering time and low temperature tempering temperature. The cryogenic treatment can effectively increase the wear resistance of the steel, and the wear amount of the steel under the cryogenic parameters as cryogenic time of 1 h, low temperature tempering temperature of 120 ℃ and low temperature tempering time of 2 h is the smallest, which is reduced by 46.67% compared with the steel without cryogenic treatment, and the wear mechanism changes to abrasive wear and oxidation wear. The carbides in the carburized layer precipitate along the grain boundaries after cryogenic treatment, while small particles of carbides are diffused on the matrix. The cryogenic treatment can reduce the retained austenite content of the steel and increase the martensite content, which increase the microhardness of the surface carburized layer, and improve the wear resistance of the 18 Cr2 Ni2 MoNbA steel.