浅冷处理和深冷处理对42CrMo钢硬度和冲击韧性的影响

Effects of Shallow and Deep Cryogenic Treatment on Hardness and Impact Toughness of 42CrMo Steel

对42CrMo钢首先锻造后淬火,再分别进行常规热处理、浅冷处理和深冷处理,之后进行中温回火,然后测试试样的硬度和冲击韧性,并采用扫描电子显微镜观察冲击试样的断口形貌和试样的微观组织,探索浅冷处理和深冷处理对42CrMo硬度和冲击韧性及微观组织的影响。结果表明,相比于常规热处理,42CrMo经浅冷处理和深冷处理后硬度略微下降,冲击韧性有所提升,并且试样经深冷处理后的冲击韧性提升程度高于浅冷处理的冲击韧性。冲击试样断口呈准解理断裂,属于脆性断裂。微观组织分析表明,浅冷处理和深冷处理均能促进试样组织中细小碳化物弥散分布析出。

42 CrMo steel was first forged and then quenched,followed by conventional heat treatment,shallow cryogenic treatment and deep cryogenic treatment respectively,then tempered at medium temperature.After this process,the hardness test and impact test of specimens were carried out.The fracture morphology and microstructure of the impact specimen were observed by scanning electron microscope.The effects of shallow and deep cryogenic treatment on hardness,impact toughness and microstructure of 42 CrMo were investigated.The results show that,compared with conventional heat treatment,the hardness of 42 CrMo steel decreases slightly after shallow cryogenic treatment and deep cryogenic treatment,and the impact toughness increases,and the impact toughness of the sample after deep cryogenic treatment is higher than that of shallow cryo genic treatment.The fracture of impact specimen is quasi-cleavage fracture,which belongs to brittle fractu re.Microstructure analysis show that both shallow cryogenic treatment and deep cryogenic treatment can promote the dispersion distribution of fine carbides in the specimen.