梁文, 冯彬, 朱国明, 康永林, 林利, 刘仁东. 1800 MPa热成形钢与CR340LA低合金高强钢激光焊接性能[J]. 工程科学学报, 2020, 42(6): 755-762. DOI: 10.13374/j.issn2095-9389.2019.06.24.005
引用本文: 梁文, 冯彬, 朱国明, 康永林, 林利, 刘仁东. 1800 MPa热成形钢与CR340LA低合金高强钢激光焊接性能[J]. 工程科学学报, 2020, 42(6): 755-762. DOI: 10.13374/j.issn2095-9389.2019.06.24.005
LIANG Wen, FENG Bin, ZHU Guo-ming, KANG Yong-lin, LIN Li, LIU Reng-dong. Laser welding properties of 1800 MPa press hardening steel and low-alloy high-strength steel CR340LA[J]. Chinese Journal of Engineering, 2020, 42(6): 755-762. DOI: 10.13374/j.issn2095-9389.2019.06.24.005
Citation: LIANG Wen, FENG Bin, ZHU Guo-ming, KANG Yong-lin, LIN Li, LIU Reng-dong. Laser welding properties of 1800 MPa press hardening steel and low-alloy high-strength steel CR340LA[J]. Chinese Journal of Engineering, 2020, 42(6): 755-762. DOI: 10.13374/j.issn2095-9389.2019.06.24.005

1800 MPa热成形钢与CR340LA低合金高强钢激光焊接性能

Laser welding properties of 1800 MPa press hardening steel and low-alloy high-strength steel CR340LA

  • 摘要: 采用光纤激光焊接设备对1800 MPa级热成形钢与CR340LA低合金高强钢进行对接激光拼焊,研究了不同激光焊接功率和焊接速度下焊接接头的组织演变规律及热冲压成形性能,并对焊接接头的力学性能和硬度进行了分析。结果表明,3种焊接工艺下激光拼焊原板综合力学性能相差较小,由焊接接头造成的伸长率和抗拉强度的损失均在母材的28.3%和9.1%以内。激光焊接后焊缝区均为粗大、高硬度的马氏体结构;两侧热影响区组织主要为铁素体和马氏体,接头未出现明显的软化区。激光拼焊原板拉伸试样均断裂于CR340LA母材区,距离焊缝12 mm左右,且存在焊缝隆起现象。选取焊接功率和焊接速率分别为4000 W和0.18 m·s−1的焊接试样在高温下进行热冲压成形检测,未出现焊缝开裂,热成形后拼焊板具有良好性能,满足汽车激光拼焊板使用要求,拉伸结果表明,试样断裂位置与未热冲压成形前一致,均位于CR340LA母材区,拉伸过程中,焊缝向高强度母材侧偏移,在弱强度母材侧产生应力集中并缩颈断裂。

     

    Abstract: A laser tailor welding experiment of 1800 MPa press hardening steel and low-alloy high-strength steel CR340LA was carried out using an optical fiber laser. The microstructure evolution and hot stamping formability of tailor-welded blanks were investigated under different laser welding powers and welding speeds, and the mechanical properties and distribution of the microhardness of the welding joints were analyzed and studied. Results show that the comprehensive mechanical properties of the laser tailor-welded blanks have little difference under three welding processes. The loss of elongation and tensile strength caused by welding joints is within 28.3% and 9.1% of the base metal. After laser welding, the fusion zone of the tailor-welded blanks is a martensite structure, which is bulky and has high hardness. The microstructure in the heat-affected zone on both sides is mainly ferrite and martensite, and there is no obvious softening zone in the joint under the welding processes. The tensile specimens of the tailor-welded blanks are all broken in the CR340LA base metal zone, approximately 12 mm away from the weld center, and a weld heave phenomenon occurs, which may be due to the uneven distribution of material properties after welding. Hot stamping of the tailor-welded blanks with a welding power and welding speed of 4000 W and 0.18 m·s−1, respectively, was carried out at high temperature, and no weld cracks were found during the experiment. Thus, these tailor-welded blanks have good performance and meet the requirements of automobile laser tailor-welded blanks. The tensile test results show that the fracture location of the specimens is the same as that before hot stamping, both of which are located in the CR340LA base metal area. During the stretching process, the fusion zone shifts to the side of the high-strength base metal, which results in a stress concentration and necking fracture on the side of the weak-strength base metal.

     

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