Q420qD钢部分熔透角接接头焊接工艺与性能研究

Welding Process and Properties of Q420qD Steel Partially Penetrated Corner Joints

采用CO_(2)气体保护焊对16 mm厚Q420qD钢进行部分熔透角接焊,对平焊、立焊和仰焊的焊接工艺进行优化设计,并分析了焊接接头的显微组织和力学性能。结果表明:在13.25~19.77 kJ/cm的焊接热输入条件下,接头焊缝和热影响区组织稳定。焊缝显微组织主要为先共析铁素体和针状铁素体,粗晶区为贝氏体、针状铁素体和珠光体的混合组织,细晶区铁素体和珠光体组织均匀分布。不同位置焊接接头的硬度变化规律为:热影响区>焊缝>母材。焊接接头的屈服强度(558~669 MPa)明显高于母材(464 MPa),拉伸断裂位置均发生在热影响区;焊缝和热影响区在-20℃的冲击功≥69 J,表现出良好的冲击韧性。

The CO_(2) gas-shielded welding was used for partial penetration corner welding of Q420qD steel with 16 mm thick‐ness,the welding process of flat,vertical and elevation weld was optimized,and the microstructure and mechanical proper‐ties of the welded joints were analyzed.The results showed that the microstructure of the weld metal(WM)and the heat-affected zone(HAZ)was stable under different heat input conditions(13.25~19.77 kJ/cm).The microstructure of the WM was mainly pre-eutectic ferrite and acicular ferrite,the coarse grain zone has a mixed bainite,acicular ferrite and pearlite,the ferrite and pearlite in the fine grain zone were uniformly distributed.The hardness of welded joints varies as follows:HAZ>WM>base material(BM).The yield strength of welded joints(558~669 MPa)was significantly higher compared to the BM(464 MPa),and the tensile fracture location all occurred in the HAZ;The impact energy of the WM and HAZ at-20℃was above 69 J,exhibiting good impact toughness.