Liu Yan, Liu Zhaozhen, Chen Yongman, He Chunlin, Liu Ao, Liu Xiaoang
Liaoning Provincial Key Laboratory of Advanced Material Preparation Technology, Shenyang University, Shenyang 110044, China.
School of Mechanical Engineering, Shenyang University, Shenyang 110044, China.
Materials (Basel). 2022 Aug 25;15(17):5880. doi: 10.3390/ma15175880.
The increasing demand for the lightweight production of advanced high-strength steel puts forward higher requirements for the quality of welded joint forming. The common CMT welding process has certain limitations and is difficult to meet the needs of lightweight manufacturing. In this study, the CMT + P welding technology was used to weld the DP980 dual-phase steel plate with 1.2 mm thickness. The ER120S-G welding wire was used as the filling material to conduct a 70° angle lap welding experiment. The effects of wire feeding speed (3 m/min5 m/min) and welding speed (350 mm/min600 mm/min) on the forming, microstructures, and mechanical properties of DP980 dual-phase steel welded joints were analyzed. The results show that the CMT + P welding process can produce lap weldments with good formability and properties. The welded joints can be divided into the weld zone, the HAZ, and the base metal zone, where the HAZ can be divided into the coarse-grained zone and the softened zone. The role of the elements Ni and Si is to promote the production of martensite and to increase the ferrite strength in welded joints. As the wire feeding speed increases, the grain size of the coarse grain zone in the HAZ increases from 31.90 μm to 50.93 μm; while the welding speed increases, the grain size of the coarse grain zone decreases from 45.48 μm to 35.73 μm. The average microhardness of the weld zone is 420 HV. In contrast, the average microhardness of the softening zone in HAZ is reduced to 250 HV. When the wire feeding speed is 4 m/min and the welding speed is 550 mm/min, the tensile properties of the weldment are optimal, its tensile strength can reach 973 MPa, and the tensile fracture is ductile fracture.
对先进高强度钢轻量化生产的需求不断增加，对焊接接头成型质量提出了更高要求。常见的冷金属过渡（CMT）焊接工艺存在一定局限性，难以满足轻量化制造的需求。本研究采用CMT+P焊接技术对厚度为1.2mm的DP980双相钢板进行焊接。使用ER120S-G焊丝作为填充材料进行70°角搭接焊接试验。分析了送丝速度（3m/min5m/min）和焊接速度（350mm/min600mm/min）对DP980双相钢焊接接头的成型、微观组织和力学性能的影响。结果表明，CMT+P焊接工艺能够生产出成型性和性能良好的搭接焊件。焊接接头可分为焊缝区、热影响区和母材区，其中热影响区可分为粗晶区和软化区。元素Ni和Si的作用是促进马氏体的生成并提高焊接接头中铁素体的强度。随着送丝速度的增加，热影响区粗晶区的晶粒尺寸从31.90μm增大到50.93μm；而随着焊接速度的增加，粗晶区的晶粒尺寸从45.48μm减小到35.73μm。焊缝区的平均显微硬度为420HV。相比之下，热影响区软化区的平均显微硬度降至250HV。当送丝速度为4m/min且焊接速度为550mm/min时，焊件的拉伸性能最佳，其抗拉强度可达973MPa，拉伸断裂为韧性断裂。
