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1 300 MPa级高强钢激光−电弧复合焊接工艺及接头微观组织演变

Laser-arc hybrid welding process and joint microstructure evolution of 1 300 MPa high strength steel

    摘要
  • 摘要:
    目的 旨在助力高强钢激光−电弧复合焊接技术在各大领域的进一步推广应用，指导生产实践。
    方法 针对9 mm厚屈服强度1 300 MPa级LG1300QT高强钢，开展激光−电弧复合焊接工艺研究、焊接相变模型开发及其接头微观组织演变仿真研究。
    结果 使用合适的工艺参数可以完成9 mm厚1 300 MPa级高强钢激光−电弧复合焊接，焊缝成形均匀一致，射线检测（Radiographic testing, RT）满足工作需求，接头抗拉强度达到母材的85%以上；仿真得到复合焊接温度场分布与焊缝截面对应一致，仿真的接头粗晶区及细晶区马氏体含量基本超过99%，与实际结果100%马氏体基本吻合，LG1300QT钢激光−电弧复合焊接接头热影响区微观组织转变以马氏体转变为主，电弧区的部分相变区（Critical heat affected zone, ICHAZ）与过渡区和激光区的ICHAZ接头微观组织演变过程差异较大，过渡区ICHAZ与激光区ICHAZ马氏体转变程度较高，而电弧区ICHAZ奥氏体化不充分，马氏体转变程度低。
    结论 对于屈服强度1 300 MPa级高强钢，激光−电弧复合焊可不开坡口单道焊成形，焊缝成形美观、接头强度较高，开发的“热−冶金”耦合模型可以较为准确地反应焊接过程中温度场及组织场特征，能够体现1 300 MPa级高强钢激光复合焊接的微观组织演变规律，对实际工程应用具有指导意义。

     

    Abstract: Objective In order to help the further popularization and application of laser-arc hybrid welding technology of high strength steel in various fields and guide production practice. Methods Aimed at the 9 mm thick yield strength of 1300 MPa grade LG1300QT high strength steel, the study on laser-arc hybrid welding technology, the development of welding phase transformation model and the simulation of the joint microstructure evolution are carried out. Results The laser-arc hybrid welding of 9 mm thick 1 300 MPa grade high strength steel can be completed by using suitable process parameters, the weld formation is uniform, RT detection meets the working requirements, and the tensile strength of the joint can reach more than 85% of the base metal.The simulation results show that the distribution of composite welding temperature field is consistent with the weld section, and the content of martensite in coarse-grained and fine-grained regions of the joint is more than 99%, which is basically consistent with the actual results of 100% martensite. The results show that the microstructure transformation in the heat affected zone of LG1300QT steel laser-hybrid welding joint is mainly martensitic transformation. The microstructure evolution of ICHAZ in arc region is quite different from that of ICHAZ in transition region and ICHAZ in laser region, the martensite transformation degree of ICHAZ in transition region and ICHAZ in laser region is higher, the ICHAZ Austenite in arc region is not sufficient and the martensite transformation is low. Conclusion For 1 300 MPa high strength steel with yield strength, laser-arc hybrid welding can be formed by single pass welding without groove, the weld formation is beautiful and joint strength is high. The developed “thermal-metallurgical” coupling model can accurately reflect the characteristics of temperature field and microstructure field in the welding process, and can reflect the microstructure evolution law of 1 300 MPa high strength steel with laser-arc hybrid welding, which has guiding significance for practical engineering application

     

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