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分别对已预热及未预热的45钢基体采用高合金药芯焊丝进行堆焊,焊后均进行空冷。利用金相显微镜和显微硬度计对焊前不同处理条件下试样的熔合区组织和硬度梯度进行对比分析。研究结果表明:焊前不同处理条件下试样的熔合区组织和硬度梯度出现明显的差异,焊前未进行预热而直接堆焊的试样,其焊接热影响区主要为力学性能较差的魏氏组织,熔覆层主要为粒状回火索氏体和残留奥氏体混合组织,且在混合组织中出现焊接裂纹,同时熔合区硬度梯度较大;焊前进行350℃×1 h预热的堆焊试样,其焊接热影响区魏氏组织消失,主要为大小均匀的粒状铁素体和珠光体,熔覆层未出现明显的焊接裂纹,同时熔合线两侧的最大硬度梯度明显降低。
Respectively, have been preheated and not preheated 45 steel substrate with high alloy flux cored welding, were air-cooled after welding. The metallographic microscope and microhardness tester were used to analyze the microstructure and hardness gradient of the fusion zone under different pre-welding conditions. The results show that the microstructure and hardness gradient of fusion zone are obviously different under different pre-welding conditions. The welding heat-affected zone mainly has poor mechanical properties Westen microstructure, the cladding layer is mainly composed of granular tempered sorbite and retained austenite, and the weld cracks appear in the mixed microstructure, and the hardness gradient of the fusion zone is relatively large. Preheating is performed at 350 ℃ for 1 h before welding The Wiegand microstructure in the HAZ disappears, which is mainly composed of granular ferrite and pearlite with uniform size. There is no obvious weld crack in the cladding layer, and the maximum hardness gradient on both sides of the fusion line is obviously reduced .