不等厚DC56D+Z/HC180BD+Z钢激光拼焊焊接接头性能分析

Performance Analysis of Laser Tailor Welded Joints of DC56D+Z/HC180BD+Z Steel with Dissimilar Thicknesses

对1.5 mm厚的DC56D+Z与0.7 mm厚的HC180BD+Z两种常用汽车板材进行激光拼焊,测试了不等厚激光拼焊板的金相组织、显微硬度和力学性能。结果表明:焊缝处与基体的金相组织均为铁素体,在焊接热循环的作用下,焊缝与基体的组织形貌差异较大。焊缝两侧硬度呈非对称分布,焊缝处最高硬度达到200 HV,高于母材。接头的单向拉伸断裂发生在HC180BD+Z钢侧,强度略低于HC180BD+Z钢母材,但断后伸长率仅为HC180BD+Z钢母材的56.8%。杯突试验后,断裂位置均发生在薄板侧,随着薄板侧占比增大,其焊缝由直线型转变为抛物线型。

Laser tailor-welding of DC56 D+Z with 1.5 mm thickness and HC180 BD+Z with 0.7 mm thickness was carried out. The metallographic microstructure, microhardness and mechanical properties were tested. The results show that the metallographic microstructure of the weld seam and the matrix is ferrite, and the difference between the weld seam and the matrix is great under the action of welding thermal cycle. The hardness of both sides of the weld seam is asymmetrical distributed, and the maximum hardness of the weld seam reaches 200 HV, which is higher than that of the base metal. The tensile fracture of the joint occurs on the side of HC180 BD+Z steel and its strength is slightly lower than that of the base metal of HC180 BD+Z steel. However, the elongation after breaking is only 56.8% of the HC180 BD+Z steel base metal. After cupping test, the fracture locations occur at the side of the thinner sheet. With the increase of the proportion of the thinner sheet, the welding seam changes from linear type to parabolic type.