【摘要】 目的 采用CMT电弧增材制造技术，在高强度模具钢表面构建具有梯度过渡特征的高强耐磨复合熔覆层，旨在提升模具钢表面硬度与耐磨性能，从而延长模具的使用寿命。方法 基于CMT电弧增材制造技术，通过选择合适的焊接材料设计出具有硬度梯度过渡的复合熔覆层。以通用的H13模具钢为基材，采用FK1000焊丝作为中间过渡层、YD322焊丝作为高强耐磨层进行逐层熔覆，以达到硬度和韧性梯度过渡的目的。结果 对熔覆后的复合材料进行微观组织和力学性能研究，结果表明，熔覆试样宏观成形良好，无明显冶金缺陷。高强耐磨层主要由细小的板条马氏体以及残余奥氏体组成，过渡层主要为贝氏体及铁素体，二次受热区和热影响区均有回火组织出现。该复合熔覆层从基材到过渡层再到高强耐磨层硬度呈梯度式提升，硬度逐级升高。该复合材料硬度从基材的248HV提升至耐磨层的581HV，硬度提高了135%。冲击韧性较基材略有下降，从基材的12 J下降到复合试样的9.3 J，其断裂方式为解理断裂。耐磨层的磨损质量为1.3 mg，磨损系数为0.365，与基材相比，磨损质量减少了69.7%，平均磨损系数从0.43降低至0.365。更多还原

【Abstract】 The work aims to study the formation of a gradient transition high-strength wear-resistant layer on the surface of high-strength die steel by CMT arc additive manufacturing, so as to obtain a composite cladding layer to improve the surface hardness and wear resistance and prolong the service life of the die. Based on CMT arc additive manufacturing technology, a composite cladding layer with hardness gradient transition was designed by selecting appropriate welding materials. With the general H13 die steel as the substrate, FK1000 welding wires were used as the intermediate transition layer, and YD322 welding wires were used as the high-strength wear-resistant layer for layer-by-layer cladding to achieve the purpose of gradient transition of hardness and toughness. The microstructure and mechanical properties of the composites after cladding were studied. The results showed that the macroscopic forming of the cladding samples was good and there were no obvious metallurgical defects. The high-strength wear-resistant layer was mainly composed of fine lath martensite and retained austenite. The transition layer was mainly bainite and ferrite, and the tempering structure appeared in the secondary heating zone and the heat-affected zone. The hardness of the composite cladding layer from the substrate to the transition layer to the high-strength wear-resistant layer was gradient, and the hardness increased step by step. The hardness of the composite increased from 248HV of the substrate to 581HV of the wear-resistant layer, and the hardness increased by 135%. The impact toughness decreased slightly from 12 J of the substrate to 9.3 J of the composite sample. And the fracture mode was cleavage fracture. The wear mass of the wear-resistant layer was 1.3 mg, and the wear coefficient was 0.365. Compared with the substrate, the wear mass was reduced by 69.7%, and the average wear coefficient was reduced from 0.43 to 0.365.更多还原