Influence of Thermal Modification on Al-Si Coating of 22MnB5 Hot Stamping Steels: Microstructure, Phase Transformation and Mechanical Properties
Influence of Thermal Modification on Al-Si Coating of 22MnB5 Hot Stamping Steels: Microstructure, Phase Transformation and Mechanical Properties
复制标题
热变质对22MnB5热冲压钢Al-Si涂层的影响：显微组织、相变和力学性能
DOI：
10.1007/s12204-021-2267-7
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Hua Xueming
中科院分区：
文献类型：
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作者：
Wang Qiongyan;Lin Wenhu;Li Fang;Shen Chen;Hua Xueming
具有高强度的热冲压钢是一种很有前途的汽车零部件材料。然而，板表面上的涂层导致焊接接头中的软化问题。热处理是一种经济有效的扩散方法，可以降低涂层中的Al浓度，而不是昂贵的涂层去除过程。在这项研究中，进行预热处理的Al-Si涂层22 MnB 5热冲压钢的Al的均匀性，然后进行激光焊接和热冲压。研究了预热对激光焊接接头组织和力学性能的影响。预热处理后，Al-Si涂层转变为Fe-Al金属间化合物，涂层与基体之间的Al含量差异减小。与未预热处理的试样相比，预热处理的试样焊缝中的Al含量降低。激光焊接后焊缝中δ铁素体数量大大减少。偏析由原来的长条状分布变为细小均匀分布。经预热处理后，焊接接头的抗拉强度显著提高，与去膜接头相当。因此，焊前预热处理是抑制δ-铁素体生成、提高焊接接头力学性能的有效方法。
The hot-stamped steel with ultrahigh strength is a promising material for the fabrication of automotive components. However, the coating on the sheet surface leads to a softening problem in the welded joint. Instead of the costly coating removal process, heat treatment is an economical and effective method for the diffusion process, which can decrease the Al concentration in the coating. In this study, a preheating treatment was carried out on Al-Si-coated 22MnB5 hot-stamped steels for the homogeneity of Al, followed by laser welding and hot stamping. The effects of the preheating on the microstructure and mechanical properties of the laser-welded joints were investigated. With the preheating treatment, the Al-Si coating transformed into an Fe-Al intermetallic compound and the difference in Al content between the coating and substrate was reduced. The Al content in the weld of the specimen with the preheating treatment was reduced, compared with that without the preheating treatment. The amount ofδ-ferrite in the weld after laser welding was reduced largely. The distribution of long-bland-like segregation was changed to a fine and uniform distribution. With the preheating treatment, the tensile strength of the welded joint was significantly improved and comparable to that of the decoated joint. In conclusion, the preheating treatment before the welding is an effective method to suppress the formation ofδ-ferrite and improve the mechanical properties of the welded joint.