基于45钢基体焊前预热对熔合区组织及硬度梯度的影响  

Study on Effect of Pre-weld Preheating on Microstructure and Hardness Gradient of 45 Steel Surfacing Welding Fusion Zone

作　　者：冯大鹏[1] 

机构地区：[1]湖北理工学院机电工程学院,湖北黄石435003

出　　处：《热加工工艺》2015年第9期221-223,共3页Hot Working Technology

基　　金：湖北省教育厅资助项目(B20114408)

摘　　要：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。Using high alloy flux-cored wire, the preheated and not preheated 45 steel were surfacing welded,respectively, after welding, air cooling treatment was taken. Then microstructure and microhardness gradient of the samples under different pre-weld processing conditions were studied by microscope and microhardness meter. The results show that the microstructure and hardness gradient of the fusion zone generate obvious differences under different preweld heat treatment conditions for substrate. There are a large number of the poor mechanical properties of widmanstatten structure in heat affected zone under the condition of unpreheating before welding, and the cladding layer is mainly granular tempered sorbite and retained austenite hybrid microstructre, and some welding cracks appear among the hybrid organization,meanwhile, the hardness gradient of fusion zone is larger. But preheating 45 steel substrate of 350 ℃×1 h before welding, the widmanstatten structure disappears in heat affected zone, which is mainly the uniform granular ferrite and pearlite. The cladding layer has no obvious welding cracks, at the same time, the maximum hardness gradient on both sides of the fusion line decreases obviously.

关 键 词：堆焊 45钢 显微组织 硬度梯度 

分 类 号：TG455[金属学及工艺—焊接]