摘要
【目的】可热处理强化Al-Mg-Si合金由于高的比强度、良好的成形性、优异的耐腐蚀性和良好的焊接性能,广泛应用于交通运输,是车辆轻量化的首选材料之一。然而,高含量Zn对合金组织和晶间腐蚀性能的影响有待进一步研究。【方法】采用室温拉伸和晶间腐蚀试验,结合SEM/EDS、EBSD和TEM表征,分析Zn元素对Al-Mg-Si合金微观组织、力学性能及晶间腐蚀性能的影响。【结果】添加Zn合金的晶粒尺寸比不添加Zn合金的大。室温拉伸性能表明,添加Zn合金的强度明显高于不添加Zn合金,但添加Zn合金的断后伸长率降低。晶间腐蚀结果表明,添加Zn合金的最大晶间腐蚀深度大于不添加Zn合金。【结论】添加Zn元素有利于减少第二相颗粒的数量,减弱对晶界的钉扎作用,增大合金的晶粒尺寸。添加Zn元素增加细小β"相的数量密度,同时促进少量的η'相析出,提高合金的强度。添加质量分数为4%的Zn能够促进晶界析出相由β相向富Zn相转变,减小晶界析出相的间距,增大PFZ的宽度,降低合金的抗晶间腐蚀性能。
[Purposes]Heat-treatable Al-Mg-Si alloy is widely used in transportation due to its high spe⁃cific strength,good formability,excellent corrosion resistance and good welding performance,which is one of the preferred materials for vehicle lightweight.However,the effect of high Zn content on the micro⁃structure and IGC properties of the alloys need to be further investigated.[Methods]Room temperature tensile and IGC tests,combined with SEM/EDS,EBSD and TEM characterization,were used to analyze the effect of high content of Zn on the microstructure,mechanical properties and IGC properties of Al-Mg-Si alloy.[Findings]The grain size of Zn-containing alloy was larger than that of Zn-free alloy.The room temperature tensile properties showed that the strength of the Zn-containing alloy was significantly higher than that of the Zn-free alloy,but the elongation of the Zn-containing alloy was lower.The IGC re⁃sults revealed that the maximum IGC depth of Zn-containing alloy was higher than that of the Zn-free al⁃loy.[Conclusions]The addition of Zn can reduce the amount of second phases,weaken the nailing effect on grain boundaries.and increase of the grain size of the alloy.The addition of Zn increases the number density of the fineβ"phase,and promotes the precipitation of a small amount ofη'phase and improve the strength of the alloy.The addition of 4 wt.%Zn promotes the transition of grain boundary precipitates fromβprecipitate to Zn-rich phase,reduces the grain boundary precipitates spacing,and increases the width of PFZ.As a result,the IGC resistance of the alloy is reduced.
作者
陈玉祥
许雪红
邓运来
CHEN Yuxiang;XU Xuehong;DENG Yunlai(Henan Zhongliming New Material Co.,Ltd.,Zhengzhou 451200,China;Central South University,Chang-sha 410083,China)
出处
《河南科技》
2024年第18期73-79,共7页
Henan Science and Technology
