王巍,张宇,乔勇.DP1180激光焊接接头微观组织及力学性能[J].精密成形工程,2024,16(10):199-207. WANG Wei,ZHANG Yu,QIAO Yong.Microstructure and Mechanical Properties of DP1180 Laser Welded Joints[J].Journal of Netshape Forming Engineering,2024,16(10):199-207. |
DP1180激光焊接接头微观组织及力学性能 |
Microstructure and Mechanical Properties of DP1180 Laser Welded Joints |
投稿时间:2024-07-28 |
DOI:10.3969/j.issn.1674-6457.2024.10.021 |
中文关键词: DP1180双相钢 激光焊接 微观组织 拉伸性能 疲劳极限 |
英文关键词: DP1180 dual phase steel laser welding microstructure tensile properties fatigue limit |
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中文摘要: |
目的 探究DP1180(抗拉强度超过1 180 MPa双相钢)激光焊接接头微观组织演变规律并分析接头力学性能。方法 采用激光焊接技术对DP1180进行了拼焊连接,利用光学显微镜和扫描电子显微镜分析接头微观组织演变,通过单轴拉伸试验及疲劳试验分析接头力学性能。结果 热影响区各微区所经历的峰值温度及冷却速率存在差异,进而导致热影响区各微区的微观组织不同,细晶区和粗晶区为全马氏体组织,不完全相变区为马氏体和铁素体的双相组织,回火区为回火马氏体和铁素体,回火区为接头的软化区。后续的焊接单轴拉伸试验结果显示,接头试样于回火区发生韧性断裂;接头试样的抗拉强度、屈服强度和断裂总延伸率分别为1 250.6 MPa、978.8 MPa和4.5%,焊缝等脆硬区的出现,使接头的断裂总延伸率降低但屈服强度提高。在后期的疲劳试验中,激光焊接造成的接头试样凹面应力集中高于其他区域,导致接头试样的疲劳极限低于母材,母材试样的疲劳极限为390.4 MPa,接头试样的疲劳极限为245.1 MPa,接头试样的疲劳极限仅为母材的62.8%。结论 激光焊接技术实现了DP1180双相钢的充分拼焊连接,激光焊接导致DP1180接头各微区微观组织存在差异,但接头的拉伸性能和疲劳性能均会降低。 |
英文摘要: |
The work aims to investigate the microstructure evolution and mechanical properties of laser welded joints of DP1180 (dual phase steel with tensile strength exceeding 1 180 MPa). DP1180 was welded by laser welding technology. The microstructure evolution of the joint was analyzed by optical microscope and scanning electron microscope. The mechanical properties of the joint were analyzed by uniaxial tensile test and fatigue test. There were differences in the peak temperature and cooling rate experienced by each micro-zone in the heat-affected zone, which led to different microstructures in the heat-affected zone. For example, fine and coarse micro-grain zones were full martensite structures, the incomplete phase transformation zone was the duplex structure of martensitic and ferrite and the tempering zone was tempered martensitic and ferrite, as well as the softening zone of the joint. The uniaxial tensile test in subsequent welding showed that the joint specimen underwent ductile fracture in the tempering zone. The tensile strength, yield strength and total elongation at break of the joint specimen were 1 250.6 MPa, 978.8 MPa and 4.5%, respectively. In the subsequent fatigue test, the stress concentration on the concave surface of the joint specimen caused by laser welding was higher than that in other zones, resulting in the fatigue limit of the joint specimen being lower than that of the base metal. The fatigue limit of the base metal sample was 390.4 MPa, the fatigue limit of the joint sample was 245.1 MPa, and the fatigue limit of the joint sample was only 62.8% of the base metal. Laser welding technology has realized the full tailor-welded connection of DP1180 dual phase steel. Laser welding leads to differences in the microstructure of DP1180 joints, and the tensile and fatigue properties of the joint will be reduced. |
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