金属热处理 ›› 2025, Vol. 50 ›› Issue (10): 292-301.DOI: 10.13251/j.issn.0254-6051.2025.10.047

• 表面工程 • 上一篇    下一篇

热基板Zn-Al-Mg镀层的组织与耐蚀性影响因素分析

李冰1, 王世豪2, 陈利伟3, 何涛1,4, 李志超2, 熊俊伟1, 张毅1   

  1. 1.中冶南方工程技术有限公司, 湖北 武汉 430223;
    2.北京科技大学 钢铁共性技术协同创新中心, 北京 100083;
    3.武汉钢铁有限公司, 湖北 武汉 430080;
    4.东北大学 轧制技术及连轧自动化国家重点实验室, 辽宁 沈阳 110819
  • 收稿日期:2025-04-18 修回日期:2025-08-06 出版日期:2025-10-25 发布日期:2025-11-04
  • 通讯作者: 李志超,副教授,博士,E-mail: lizhichao1225@163.com
  • 作者简介:李 冰(1991—),男,高级工程师,博士研究生,主要研究方向为金属镀层钢新产品开发及工艺研究,E-mail: 405111648@qq.com。

Analysis of factors affecting microstructure and corrosion resistance of Zn-Al-Mg coating on hot-rolled steel

Li Bing1, Wang Shihao2, Chen Liwei3, He Tao1,4, Li Zhichao2, Xiong Junwei1, Zhang Yi1   

  1. 1. WISDRI Engineering and Research Co., Ltd., Wuhan Hubei 430223, China;
    2. Collaborative Innovation Center of Steel Technology, University of Science and Technology Beijing, Beijing 100083, China;
    3. Wuhan Iron and Steel Co., Ltd., Wuhan Hubei 430080, China;
    4. State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang Liaoning 110819, China
  • Received:2025-04-18 Revised:2025-08-06 Online:2025-10-25 Published:2025-11-04

摘要: 以1.2~3.0 mm厚SPHC板为基板,Zn-11%Al-2.8%Mg-0.2%Si锌锭熔化为热浸镀液,采用连续热浸镀模拟试验机制备了Zn-Al-Mg镀层,研究板厚、入锅板温以及镀后冷却速度对镀层组织与耐蚀性的影响。结果表明,在冷速固定的情况下,制备镀层的最佳板厚和入锅板温分别为2.4 mm和480 ℃。在此基础上,研究冷速对镀层耐蚀性的影响。随冷速增加,镀层中富Al相与MgZn2相细化且占比增多,共晶相变得粗大,当冷速超过10 ℃/s后,镀层中开始出现枝晶,并伴随着块状MgZn2相的出现,且共晶相面积减小,耐蚀性逐渐降低,同时结合565 h盐雾试验判断最佳冷却速度为10 ℃/s。最佳工艺参数(板厚2.4 mm、板温480 ℃及冷速10 ℃/s)制备镀层厚度达42.516 μm,且组织中富Al相尺寸稍大且饱满,分布连贯,共晶相的分布均匀,耐蚀性较好。

关键词: 热浸镀, Zn-Al-Mg镀层, 组织, 耐蚀性

Abstract: Using SPHC steel sheets with 1.2-3.0 mm thickness as the substrate and a molten Zn-11%Al-2.8%Mg-0.2%Si alloy ingot as the hot-dip bath, Zn-Al-Mg coatings were prepared by using a continuous hot-dip simulation test setup, then the effect of sheet thickness, pot entry temperature, and post-coating cooling rate on microstructure and corrosion resistance of the coating was investigated. The results show that with a fixed cooling rate, the optimal sheet thickness and pot entry temperature for preparing the coating are 2.4 mm and 480 ℃, respectively. Based on these findings, the effect of cooling rate on corrosion resistance of the coating was studied. As the cooling rate increases, the Al-rich phase and MgZn2 phase in the coating become finer and their proportion increase, while the eutectic phase becomes coarser. When the cooling rate exceeds 10 ℃/s, dendrites begin to appear in the coating, accompanied by the presence of block-shaped MgZn2 phase. Concurrently, the area fraction of the eutectic phase decreases, and the corrosion resistance is gradually deteriorated. Combined with 565 h of salt spray test results, the optimal cooling rate is determined to be 10 ℃/s. Under the optimal process parameters (sheet thickness of 2.4 mm, pot entry temperature of 480 ℃ and cooling rate of 10 ℃/s), the prepared coating achieves a thickness of 42.516 μm. Furthermore, the Al-rich phase in the microstructure is slightly larger and plumpier, with continuous distribution. The eutectic phase is uniformly distributed, and the corrosion resistance is good.

Key words: hot-dip galvanizing, Zn-Al-Mg coating, microstructure, corrosion resistance

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