手工电弧焊SS400钢焊接接头组织及硬度研究

采用不同热输入手工电弧焊对8nm厚SS400钢板进行焊接性试验，并通过金相观察和显微硬度测定得到了接头显微组织分布及硬度变化规律。试验结果表明，当焊接热输入为16kJ／cm时，焊接接头存在未焊透的现象；随焊接热输入的增加，热影响区的苋度从1．9mm增大到4．3mm，粗晶平均直径也咯有增大；热输入达到27kJ／cm时，焊缝组织得到较多的针状铁素体，但过热粗晶区晶粒粗大，占整个热影响区的比例达到了52％；不同热输入各区域的显微硬度较母材均有所提高，热输入为27KJ／cm时，焊缝硬度较母材增大30％左右，达到最大增幅．

Research on microstructure and micro-hardness in welded joints of SS400 using shielded metal arc

Shiehled metal are welding method wilh differen! heat inpul was used to carry on the wehlding tests for the 8mm SS400 plate. The mierostrueture and micro-hardness distribution in wehled joints were analyzed through lnetallographic microscopes and micro-hard- ness tesler. The resuhs shrew that the wehted joint was not eomplelely penetrated when the heat input came 1o 16KJ/cm. The width of HAZ ranges from 1.9 mm to 4.3 mm and the average diameters of the coarse grain increase slightly as well widl the increasing of heal input. When the heat input came to 27 KJ/em, more aeieular ferrites were obtained in the wehl zone, but tire grains in the Coarse-grain region grew bigger,aeeotmling for 52 pereenl of the whole HAZ. The micrn-hardness distribnlion wlries every different zone with the improvement of welding heal input. When the heat input came to 27 KJ/cm,the miern-hardness in wehl zone increases approximalely 30% more Ihan that of the base mental.