Experimental investigation and kinetic analysis of Al–Zn–Mg alloy coating

IF 1.9 3区 材料科学 Q4 CHEMISTRY, PHYSICAL
Chengliang Xu , Huaxiang Teng , Yun Han , Guangrui Jiang , Huasai Liu , Yanhui Hu
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引用次数: 0

Abstract

The hot-dip 55 wt%Al–Zn-1.6 wt%Si-(0–3)wt.%Mg alloy coatings were experimentally investigated, and the solidification behaviors and hot cracking susceptibility were simulated by means of CALPHAD (CALculation of PHAse Diagrams) method. The scanning electron microscopy (SEM), electron probe micro-analyzer (EPMA) and glow discharge spectrometer method (GDS) were utilized to determine the microstructures and the distribution of elements of the Al–Zn–Mg alloy coatings with different Mg contents. It is discovered that with the increase of Mg content, the percentage of the eutectic microstructure scales up, and the surface quality of the alloy coating is improved. Meanwhile, the bending properties of Al–Zn–Mg coatings with different Mg contents still requires further improvement according to the present bending test. Subsequently, the equilibrium solidification processes of the coatings were calculated using thermodynamic approach. In general, the calculated results reflect the solidified phases and the precipitated temperatures according to theory of equilibrium solidification. However, there still exist discrepancies between the thermodynamic calculation results and the observed experimental results during the practical galvanizing process, because the cooling rates were not taken fully into consideration. Consequently, the kinetic analysis was carried out to obtain the secondary dendrite arm spacing under different cooling rates. The cracking susceptibility index (CSI) was also calculated to predict the hot workability of the Al–Zn–Mg alloy coating. In summary, the appropriate increase of the cooling rate turns out be the effective approach to benefit the microstructure and the corrosion resistance of the Al–Zn–Mg coatings in the practical galvanizing process, and the coating is not suitable for the hot stamping process.

铝锌镁合金涂层的实验研究和动力学分析
实验研究了热浸 55 wt%Al-Zn-1.6 wt%Si-(0-3)wt.%Mg 合金镀层,并采用 CALPHAD(CALculation of PHAse Diagrams)方法模拟了其凝固行为和热裂纹敏感性。利用扫描电子显微镜(SEM)、电子探针显微分析仪(EPMA)和辉光放电光谱仪(GDS)测定了不同镁含量的铝锌镁合金镀层的微观结构和元素分布。结果发现,随着镁含量的增加,共晶微观结构的比例增大,合金镀层的表面质量得到改善。同时,根据目前的弯曲试验,不同镁含量的 Al-Zn-Mg 涂层的弯曲性能仍有待进一步提高。随后,利用热力学方法计算了涂层的平衡凝固过程。总体而言,计算结果反映了根据平衡凝固理论得出的凝固相和析出温度。然而,在实际镀锌过程中,由于没有充分考虑冷却速率,热力学计算结果与观察到的实验结果之间仍存在差异。因此,我们进行了动力学分析,以获得不同冷却速率下的二次枝晶臂间距。此外,还计算了开裂敏感性指数(CSI),以预测铝锌镁合金镀层的热加工性能。总之,在实际镀锌工艺中,适当提高冷却速率是有利于 Al-Zn-Mg 涂层微观结构和耐腐蚀性能的有效方法,但该涂层不适合热冲压工艺。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
CiteScore
4.00
自引率
16.70%
发文量
94
审稿时长
2.5 months
期刊介绍: The design of industrial processes requires reliable thermodynamic data. CALPHAD (Computer Coupling of Phase Diagrams and Thermochemistry) aims to promote computational thermodynamics through development of models to represent thermodynamic properties for various phases which permit prediction of properties of multicomponent systems from those of binary and ternary subsystems, critical assessment of data and their incorporation into self-consistent databases, development of software to optimize and derive thermodynamic parameters and the development and use of databanks for calculations to improve understanding of various industrial and technological processes. This work is disseminated through the CALPHAD journal and its annual conference.
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