2Cr13 马氏体不锈钢力学性能优异、耐蚀性适中且价格低廉,具有较好的利润空间,一直以来是钢铁企业尝试发展的焦点.先前研究表明激光-电弧复合工艺有望通过焊丝材料的合理选择,借助合金化的作用实现 2Cr13不锈钢的高质高效焊接,但存在合金元素分布不均的问题.为此,本文在 2Cr13 马氏体不锈钢激光-电弧复合焊接中引入激光束扫描,依靠其对熔池的强烈搅拌效应调控合金元素分布,改善熔池冶金行为,细化晶粒,从而增强焊缝韧性.本文着重探讨了激光束扫描频率对焊缝中合金元素分布特征、焊缝组织和力学性能的影响规律.结果表明,扫描激光束对熔池的高频搅拌效应加强了熔池对流,驱动 Ni 元素由电弧作用区域向激光作用区域转移,焊缝中 Ni元素分布不均匀程度减弱.在扫描半径 0.4 mm 情况下优化的扫描频率为 20 Hz,此时焊缝中激光作用区域 Ni 元素含量由不引入激光束扫描时的 1.52%提高至 2.03%,对应的奥氏体相含量由 4.7%增加至 10.1%.同时,激光束扫描行为降低了熔池温度梯度,有利于改善焊缝成形,热影响区粗晶区平均晶粒尺寸由 4.92µm降为 3.95µm,焊缝杯突测试中断裂位置由熔合线转向母材,且杯突值由 4.82 mm 提升至 5.89 mm,提升幅度达 22%.相关研究将对以后马氏体不锈钢焊接研究提供一定的理论指导,对扩大马氏体不锈钢的应用领域具有重要的推动作用.
Elemental Distribution,Microstructure,and Mechanical Properties of 2Cr13 Martensitic Stainless Steel Processed via Hybrid Oscillating Laser-Arc Welding
The development of 2Cr13 martensitic stainless steel has long been sought in the steel industry because of the excellent mechanical properties,moderate corrosion resistance,and affordable price of the steel,which provide high profit margins.Studies have shown that hybrid laser-arc welding holds promise for realizing high-quality and efficient welding of 2Cr13 stainless steel by rationally selecting welding wire materials and leveraging alloying effects.However,there is an issue of the uneven distribution of alloying elements in hybrid laser-arc welding.To solve this issue,an oscillating laser beam was used during the hybrid laser-arc welding of 2Cr13 martensitic stainless steel.The oscillating laser beam can regulate the distribution of alloying elements through its intense stirring effect,which im-proves the metallurgical behavior and refines grains,enhancing the toughness of the weld.Further,the influence of the oscillating frequency of laser beam on the distribution characteristics of alloying elements in the weld,as well as the weld microstructure and mechanical properties,were investigated.Results show that the high-frequency stirring effect of the oscillating laser beam on the molten pool enhanced convection in the molten flow,promoted the transfer of Ni from the arc zone to the laser zone,and reduced the nonuniform distribution of Ni in the weld.The optimized oscillating frequency was 20 Hz at an oscillating radius of 0.4 mm.For this frequency,the Ni content in the laser zone was increased from 1.52%when not using an oscillating laser beam to 2.03%when using an oscillating laser beam;the corresponding fraction of the austenitic phase was increased from 4.7%to 10.1%.In addition,the temperature gradient of the molten pool was reduced by the oscillating laser beam,which improved weld formation.The average size of the coarse grain area in the heat-affected zone was reduced from 4.92 μm to 3.95µm,the fracture location was shifted from the fusion line to the base metal during a cupping test,and the cupping value was increased from 4.82 mm to 5.89 mm,showing an increase of 22%.These results will help deepen our understanding of the hybrid laser-arc welding of martensitic stainless steel and broaden its application range.
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