Li Muyu, Yao Dan, Guan Yingping, Duan Yongchuan, Yang Liu
Key Laboratory of Advanced Forging & Stamping Technology and Science, Yanshan University, Ministry of Education of China, Qinhuangdao 066000, China.
School of Mechanical Engineering, Yanshan University, Qinhuangdao 066000, China.
Materials (Basel). 2020 Oct 18;13(20):4645. doi: 10.3390/ma13204645.
In this research, B1500HS high-strength steel with different thicknesses were laser welded, and the effects of welding speed and post quenching were investigated by analyzing the microstructure, microhardness distribution, and high-temperature tensile properties of weld joints. The results show that an obvious difference can be found in the metallographic structure and grain morphology of the weld joint at different locations, which also lead to the significant uneven distribution of hardness. After quenching, the grain size of the original heat-affected zone was uniform, the columnar grains in the fusion zone were transformed into fine equiaxed grains, and no obvious hardness difference can be found in the weld joint. For the weld joint without quenching, the increase of welding speed can reduce the dimensions of grains of fusion zone and coarse grain zone, and slightly increase the hardness of these regions. In contrast, welding speed change has little influence on the microstructure and hardness of the weld joint after quenching. The high-temperature flow stress-strain curves of fusion zone welded under different welding speeds were calculated based on the mixture rule. The analysis results indicated that the fusion zone has higher strength but lower elongation than the base metal. In addition, the change of welding speed has a small impact on the high-temperature tensile properties of the fusion zone.
在本研究中，对不同厚度的B1500HS高强度钢进行了激光焊接，并通过分析焊接接头的微观结构、显微硬度分布和高温拉伸性能，研究了焊接速度和焊后淬火的影响。结果表明，在不同位置的焊接接头金相组织和晶粒形态存在明显差异，这也导致了硬度的显著不均匀分布。淬火后，原始热影响区的晶粒尺寸均匀，熔合区的柱状晶转变为细小等轴晶，焊接接头中未发现明显的硬度差异。对于未淬火的焊接接头，焊接速度的增加可减小熔合区和粗晶区的晶粒尺寸，并略微提高这些区域的硬度。相比之下，焊接速度的变化对淬火后焊接接头的微观结构和硬度影响较小。基于混合法则计算了不同焊接速度下焊接的熔合区高温流变应力-应变曲线。分析结果表明，熔合区的强度高于母材，但伸长率低于母材。此外，焊接速度的变化对熔合区的高温拉伸性能影响较小。
