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采用Fe-Cr-Ni系药芯焊丝在ZG25CrNiMn基体表面进行埋弧堆焊,焊后分别进行空冷及200、300、400、500、600℃不同温度回火处理。通过金相显微观察、硬度检测、摩擦试验以及冲击试验和SEM扫描等试验方法分析了焊后不同处理对堆焊层组织、硬度、耐磨性及断裂机理的影响规律。结果表明:焊后采取不同处理,堆焊层的组织形貌、硬度、耐磨性以及断口形貌存在较大差异。焊后空冷条件下,堆焊层主要为粗大的片状马氏体组织,硬度较高,耐磨性及冲击韧性较低,断裂面出现较多的大面积平整断裂面,表现为明显的脆性断裂。焊后200℃低温回火条件下,组织和力学性能变化较小,当回火温度超过200℃时,随着回火温度的升高,堆焊层中原有的粗大片状马氏体逐渐减少,细小的板条状回火马氏体逐渐增多,硬度逐渐降低,耐磨性逐渐提高,同时堆焊层的韧性逐渐得到改善,断裂面中逐渐出现一定数量的较小较深的断裂韧窝。当回火温度达到500℃时,堆焊层的硬度降低,耐磨性较高,断裂面的断裂韧窝较多,当回火温度达到600℃时,堆焊层主要表现为细小的粒状回火索氏体,耐磨性降低。
Fe-Cr-Ni flux cored wire was used for submerged arc welding on the surface of ZG25CrNiMn substrate. After welding, they were air-cooled and tempered at different temperatures of 200, 300, 400, 500 and 600 ℃ respectively. The influences of different post-welding treatments on the microstructure, hardness, wear resistance and fracture mechanism of overlay were analyzed by metallographic observation, hardness test, friction test, impact test and SEM scanning. The results show that there are great differences in the morphology, hardness, wear resistance and fracture morphology of the surfacing layer after different treatments. Under the condition of air-cooling after welding, the overlay welding mainly consists of coarse sheet-like martensite with high hardness, low wear resistance and impact toughness, and large flattened fracture surface with more fractures, showing obvious brittleness fracture. Under 200 ℃ low temperature tempering, the microstructure and mechanical properties change little. When the tempering temperature exceeds 200 ℃, as the tempering temperature increases, the original coarse lamellar martensite in the overlay decreases , Small lath tempered martensite gradually increased hardness gradually decreased wear resistance gradually increased at the same time, the toughness of the surfacing layer gradually improved, the fracture surface in the gradual emergence of a number of smaller deep deep dimples . When the tempering temperature reaches 500 ℃, the hardness of the overlay decreases, and the wear resistance is higher. There are more fracture dimples in the fracture surface. When the tempering temperature reaches 600 ℃, the overlay is mainly composed of fine granular Sorbitol fire, wear resistance reduced.