30CrMo板CMT再制造熔覆层成形及组织性能

目的 研究预制槽坡口角度对冷金属过渡(CMT)再制造30CrMo板熔覆层成形质量的影响规律，探明熔覆层的微观组织和力学性能，为30CrMo零部件CMT再制造提供参考。方法 利用CMT再制造含预制槽的30CrMo板，分析预制槽坡口角度对熔覆层成形质量的影响;基于优选的坡口角度，对30CrMo腰型槽进行CMT再制造，研究所得熔覆层的成形质量，利用金相显微镜表征熔覆层的微观组织，并测试熔覆层的力学性能。结果 预制槽坡口角度对最后一道焊缝与母材的熔合有显著影响，坡口的角度应不小于40°;腰型预制槽再制造时，焊道与母材、焊道间形成了良好的冶金结合，熔覆层主要由针状铁素体和粒状贝氏体组成，微观组织形态主要是柱状晶和等轴晶，不同区域的微观组织形态存在差异;40°坡口熔覆层的抗拉强度可达1 014 MPa、伸长率为10.88%，50°坡口熔覆层的抗拉强度可达1 128 MPa、伸长率为6.39%。结论 熔覆层和母材形成了良好的冶金结合，熔覆层具有良好的力学性能，满足30CrMo钢的再制造强度要求，采用CMT进行30CrMo板再制造是可行的。

Formation, Microstructure and Properties of Cladding Remanufacted by CMT on 30CrMo Plates

The work aims to study the effect of prefabricated groove angle on the forming quality of cladding layer remanufactured by cold metal transfer (CMT), and explore the microstructure and mechanical properties of the cladding layer to provide reference for CMT remanufacturing of 30CrMo components. Hence, the CMT was used to remanufacture 30CrMo plates with prefabricated grooves to analyze the effect of prefabricated groove angles on the forming quality of the cladding. Based on the optimized groove angle, the 30CrMo waist-shaped groove was subject to CMT remanufacturing to study the forming quality of the cladding remanufactured. The microstructure and mechanical properties of the cladding remanufactured were characterized and tested with a metalloscope. The results showed that the angle of the prefabricated groove had a significant impact on the fusion between the last weld seam and the base metal, so the angle of the groove should not be less than 40°. A good metallurgical combination was formed between the weld beads, the base metal and the weld beads when the waist-shaped prefabricated groove was remanufactured. The cladding was mainly composed of acicular ferrite and granular bainite. The microstructure morphology was predominant by columnar and equiaxed grains, and different regions were featured with different morphology. The tensile strength and elongation rate of the remanufactured cladding with a groove angle of 40° were 1 014 MPa and 10.88%, while that with a groove angle of 50° are 1 128 MPa and 6.39%, respectively. There is a good metallurgical combination between the cladding and the base metal. The cladding layer has good mechanical properties, which can satisfy the remanufacturing strength requirements of 30CrMo steel. Therefore, it is feasible to remanufacture 30CrMo plates by CMT.