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采用激光焊接的方法对1.5 mm厚的DOGAL 800DP高强度镀锌钢板进行对接焊,通过用金相显微镜对接头显微组织进行观察,用万能拉伸试验机对接头抗拉强度及伸长率进行测试,研究了焊接速度对其焊接接头组织和力学性能的影响。结果表明,焊缝组织主要为贝氏体+少量的先共析铁素体及侧板条铁素体,热影响区组织主要为板条马氏体+贝氏体,马氏体含量明显高于焊缝;随着焊接速度提高,焊缝中铁素体含量减少,马氏体含量增加,热影响区组织细化,接头抗拉强度和伸长率均先升高后降低,当焊接速度为0.8 m/min时强度最高,1.0 m/min时伸长率最大;焊接速度高于1.2 m/min或低于0.6 m/min都不利于获得力学性能优良的焊接接头,当焊接速度为1.0 m/min时,接头具有最佳强塑性匹配。
The 1.5 mm thick DOGAL 800DP high strength galvanized steel sheet was butt welded by laser welding. The microstructure of the joint was observed with a metallographic microscope. The tensile strength and elongation of the joint were measured with a universal tensile testing machine The effects of welding speed on the microstructure and mechanical properties of the welded joint were studied. The results show that the microstructure of the weld is mainly bainite + a small amount of proeutectoid ferrite and side lamellar ferrite. The microstructure of the heat affected zone is mainly lath martensite + bainite, and the content of martensite is obviously high With the increase of welding speed, the content of ferrite in weld decreases, the content of martensite increases and the microstructure of HAZ refinement. The tensile strength and elongation of joint increase at first and then decrease. When the welding speed is 0.8 When the welding speed is 1.0 m / min, the elongation is the highest. If the welding speed is higher than 1.2 m / min or lower than 0.6 m / min, it is unfavorable to obtain the welded joints with excellent mechanical properties. When the welding speed is 1.0 m / min, the joints have the best plastic matching.