高强钢热镀锌板选择性氧化和润湿性研究

High strength hot-dip galvanized steel sheets are widely used as a means of realizing weight reduction in automo-bile bodies. However, in the annealing process selective oxidation occurs at the strip surface. This is known to cause the so-called barespot defect because these selective surface oxides deteriorate wettability between the molten zinc and the base materials. An understanding of the selective surface oxidation behavior is extremely important for practical application of high strength steel sheets. Fe-M-X-O(（M、X）=Mn、Cr、Al、Si、P、Mo、Ti and Nb) quaternary system will be experimentally determined and thermodynamically optimized, The thermodynamic description will be obtained. The influence of the steel chemistry and parameters of heat treatment on the selective oxidation behavior and the variety and morphology of the surface oxide will be investigated. The selective oxidation behaviors of high strength steel sheets during intercritical annealing based on thermodynamics and kinetics will be analyzed. To improve the wettability, the effects of the variety and morphology of the surface oxide on the wettability of liquid Zn with steel sheets will be evaluated by the sessile drop method. This research will accumulate knowledge for high strength hot-dip Zn galvanized steels，which is important reference for the quality improvement of coating and the development of new high strength steels.

为了减少汽车重量，高强钢热镀锌板得到广泛关注；然而钢板表面的选择性氧化恶化钢板润湿性，导致热浸镀锌时容易出现漏镀缺陷，严重影响钢板表面质量。为更好的应用高强钢热镀锌板，本项目将实验测定低露点条件下Fe-M-X-O（（M、X）=Mn、Cr、Al、Si、P、Mo、Ti和Nb)四元系相平衡，对体系进行热力学优化评估，获得体系的热力学参数；实验研究不同合金成分和工艺参数条件下选择性氧化的形成过程、氧化物种类和形貌，采用所获得的相平衡、热力学和动力学数据分析氧化反应过程；用液滴法系统研究氧化物种类和形貌对钢板表面润湿性影响，分析锌液与含氧化物表面的钢的界面反应过程，探索改善钢板表面润湿性能的方法。这些将丰富低露点高强钢合金体系基础数据和界面反应理论，对提高镀层质量和开发高强钢具有重要的参考作用。

为了减少汽车重量，高强钢热镀锌板得到广泛关注；然而钢板表面的选择性氧化恶化钢板的润湿性，导致热浸镀锌时容易出现漏镀缺陷，严重影响钢板表面质量。为更好的应用高强钢热镀锌板，本项目研究了不同露点和温度下以Fe、Mn、Al、Cr、Si等为主要组元的多元系相平衡和氧化物稳定性；基于初始氧化物相图的实验测定和热力学计算，构建了低氧压下高强钢选择性氧化的热力学数据库；通过选择性氧化实验，确定了工艺条件对不同高强钢选择性氧化的形成过程、氧化物种类和形貌的影响；通过研究锌液与含氧化物表面的高强钢的界面反应过程，明确了钢板表面氧化物和形貌对锌液润湿性的影响；结合热力学和动力学数据，提供了抑制高强钢钢板表面选择性氧化的工艺方案，改善后期钢板的可镀性。