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| 热成形淬火对QP1180/22MnB5激光拼焊板组织与性能的影响 |
| Effect of Hot Forming on Microstructure and Mechanical Properties of Laser Tailor-welded Blank |
| Received:September 21, 2023 |
| DOI：10.3969/j.issn.1674-6457.2024.01.013 |
| 中文关键词: 异种高强钢 激光拼焊 热冲压成形 力学性能 微观组织 |
| 英文关键词: dissimilar high strength steel laser welding hot stamping forming mechanical properties microstructure |
| 基金项目:先进焊接与连接国家重点实验室开放课题基金(AWJ-23M25);中央引导地方科技专项基金(2019ZYYD023) |
| Author Name | Affiliation | | SU Wenchao | School of Materials Science and Engineering, Hubei University of Automotive Technology, Hubei Shiyan 442002, China | | WANG Jinfeng | School of Materials Science and Engineering, Hubei University of Automotive Technology, Hubei Shiyan 442002, China | | CHE Yajun | Dongfeng Motor Parts and Components Group Co., Ltd., Hubei Shiyan 442016, China | | GUO Yi | School of Materials Science and Engineering, Hubei University of Automotive Technology, Hubei Shiyan 442002, China | | WANG Jing | Hubei Changping Automobile Equipment Co., Ltd., Hubei Shiyan 442000, China |
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| 中文摘要: |
| 目的 对QP1180和22MnB5激光拼焊板进行热成形试验，以解决超高强钢板材焊后的软化问题。方法 选择QP1180和22MnB5异种高强钢作为母材进行激光自熔焊，对焊后的激光拼焊板进行热成形试验，通过体式显微镜、扫描电子显微镜、液压拉伸试验机和维氏硬度计等手段，分析热成形前后激光拼焊板微观组织和力学性能的变化。结果 与焊态拉伸试样相比，热成形试样抗拉强度提高了135%，断后伸长率降低了55%，拉伸试样都在22MnB5母材处断裂，均为塑性断裂。在热成形后，对焊接接头进行组织分析，发现QP1180母材区马氏体含量增加，22MnB5母材区和临界热影响区组织由珠光体和铁素体转变为马氏体，焊接接头热影响区各亚区的组织均转变为大小不同的板条马氏体。硬度测试结果表明，焊态试样焊接接头的QP1180临界区存在软化现象，硬度值最低为335HV，22MnB5侧硬度值由母材处向焊缝升高，母材硬度最低为170HV;而在热成形后，QP1180临界区软化现象消失，硬度值趋于平缓，22MnB5母材处硬度比焊态试样硬度高了2倍。结论 与焊态试样相比，经热成形后激光拼焊板的焊后软化问题得到了解决。 |
| 英文摘要: |
| The work aims to solve the softening problem of ultra-high strength steel plate after welding by hot forming test of QP1180 and 22MnB5 laser tailor-welded blanks. QP1180 and 22MnB5 dissimilar high strength steel materials were selected as the base metal for laser self-fusion welding. The hot forming test was carried out on the laser tailor-welded blanks after welding. The changes of microstructure and mechanical properties of laser tailor-welded blanks before and after hot forming were analyzed by means of stereo microscope, scanning electron microscope, hydraulic tensile testing machine and Vickers hardness tester. Compared with the as-welded tensile specimen, the tensile strength of the hot-formed specimen increased by 135%, and the elongation after fracture decreased by 55%. The tensile specimens all broken at the base metal of 22MnB5, all of which were subject to plastic fracture. After hot forming, the microstructure of the welded joint was analyzed. The martensite content in the QP1180 base metal area increased, and in the 22MnB5 base metal area and the critical heat affected zone pearlite and ferrite changed to martensite. The microstructure of each sub-zone of the heat affected zone of the welded joint was transformed into lath martensite of different sizes. The hardness test results showed that there was a softening phenomenon in the QP1180 critical zone of the welded joint under the as-welded sample, and the lowest hardness value was 335HV. The hardness value of the 22MnB5 side increased from the base metal to the weld, and the lowest hardness of the base metal was 170HV. After hot forming, the softening phenomenon in the critical zone of QP1180 disappeared, and the hardness value tended to be gentle. The hardness of 22MnB5 base metal was 2 times higher than that of the as-welded sample. Compared with the as-welded state, the laser tailor-welded blanks can significantly solve the post-weld softening problem of ultra-high strength steel after hot forming. |
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