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采用扫描电子显微镜、维氏显微硬度计及成形机分析表征了冷连轧带钢焊接接头从焊缝到热影响区的显微组织与力学性能。结果表明,冷连轧带钢焊接接头的显微组织由粒状贝氏体、板条贝氏体及少量的马氏体-奥氏体组元组成,在临界粗晶区还出现大量多边形铁素体;显微硬度值在焊缝区域最高,在热影响区出现波动,在临界粗晶区明显下降并逐渐接近母材硬度;杯突测试后发现裂纹源于临界粗晶区,经少量塑性变形后呈韧性断裂。
The microstructure and mechanical properties of cold-rolled strip welded joints from weld to HAZ were characterized by scanning electron microscopy, Vickers microhardness tester and forming machine. The results show that the microstructure of cold-rolled strip welded joint consists of granular bainite, lath bainite and a small amount of martensite-austenite. In the critical coarse grain region, a large amount of polygonal ferrite The microhardness value is the highest in the weld zone and fluctuates in the heat affected zone, decreases obviously in the critical coarse grain zone and gradually approaches the hardness of the base material. After the cup test, it is found that the crack originates from the critical coarse grain zone and undergoes a small amount of plastic deformation After the ductile fracture.