冷轧DP980电阻点焊接头断裂模式特征与组织分析  

Fracture mode characteristics and microstructure analysis ofresistance spot welded joint of cold rolled DP980

作　　者：吕冬[1] 芦延鹏 刘仁东[1] 林利[1] 丁庶炜[1] Lü Dong;Lu Yanpeng;Liu Rendong;Lin Li;Ding Zhewei(Angang Steel Company Limited,Anshan 114009,Liaoning,China)

机构地区：[1]鞍钢股份有限公司

出　　处：《焊接》2019年第10期52-57,I0005,共7页Welding & Joining

摘　　要：采用中频逆变点焊机对1.2 mm厚冷轧DP980进行电阻点焊试验,确定球形电极下焊点的断裂模式,对不同断裂模式下的熔核直径、剪切力、破坏能量及断裂位移等参数进行表征。此外,针对典型熔核组织和显微硬度进行分析。结果表明,球形电极下焊点断裂模式表现为界面断裂和熔核拔出两种。两种断裂模式下,熔核处组织均为板条马氏体+孪晶马氏体,在热影响区中存在软化区域,该组织为回火马氏体+铁素体。界面断裂模式下,熔核直径、剪切力及断裂位移均呈现为数值较小的特点,破坏能量随焊接电流的增加呈快速增长的特征。熔核拔出模式下,熔核直径、剪切力和断裂位移均呈现为数值较大的特点,破坏能量随焊接电流的增加呈稳定状态。Resistance spot welding test was applied to DP980 steel with 1.2 mm thickness by a medium frequency inverter welding machine,through which fracture mode of welding points under the spherical electrode was determined.Moreover,parameters of diameter of nugget,shear force,failure energy and fracture displacement under different fracture modes were characterized.In addition,typical microstructures and microhardness of welding points were analyzed.The results indicated that the fracture mode of welding points under the spherical electrode exhibited with interface fracture and nugget draw.Both in the two fracture modes,microstructures of nugget were composed of lath martensite and twinning martensite.The soften zone could be observed in HAZ,in which microstructures consisted of tempered martensite and ferrite.Under the mode of interface fracture,values of diameter of nugget,shear force and fracture displacement exhibited low,and failure energy fast increased with the increasing of welding electricity.Under the mode of nugget draw,values of diameter of nugget,shear force and fracture displacement exhibited high,and failure energy waved little with the increasing of the welding electricity.

关 键 词：DP980 点焊 双相钢 断裂模式 

分 类 号：TG406[金属学及工艺—焊接]