Zn元素对7072Al合金微观组织与性能的影响

发布时间：2018-01-25 22:05

本文关键词： 7072Al合金 Zn元素微观结构力学性能耐蚀性　出处：《上海交通大学》2015年硕士论文　论文类型：学位论文

【摘要】：7072Al合金是一种重要的热传输材料,广泛应用于热交换器。本文通过微结构分析、拉伸试验、电化学测试等方法系统研究了Zn元素含量对模拟钎焊态和退火态7072Al合金的微观组织、力学性能与电化学性能的影响。对于模拟钎焊合金,增加Zn元素含量可促进7072Al合金中析出相的析出,且当Zn元素添加量为1.3%时,促进析出作用最为明显,进一步增加Zn元素含量,析出相密度变化不大。力学实验结果表明,Zn元素有利于提高7072Al合金的机械性能,随着Zn含量的增加,其屈服强度、抗拉强度和延伸率均有所提高。电化学实验结果表明,提高Zn含量会使7072Al合金在0.5%NaCl,3.5%NaCl和1M NaCl+0.3M H2O2溶液体系中的腐蚀电位负移。但当Zn元素添加量由1.5%提高到2.5%时,合金的腐蚀电位在三种溶液中均无明显改变,此时Zn元素的添加对合金腐蚀电位影响作用不再明显。对于退火态合金,不同Zn添加量的7072Al合金中析出相密度相差不大,因此合金的屈服强度、抗拉强度以及延伸率都相近,且合金的断裂方式为韧性断裂。7072Al+1.3%Zn与7072Al+1.5%Zn合金在0.5%NaCl,3.5%NaCl和1M NaCl+0.3M H2O2溶液体系中的抗腐蚀性能相近。相对于7072Al+1.3%Zn与7072Al+1.5%Zn合金,7072Al+2.5%Zn合金的腐蚀电位负移,腐蚀电流增大,腐蚀程度加剧。此外,对于所有合金,随着NaCl溶液中氯离子浓度的增大,合金表面点蚀坑更为密集,合金的腐蚀程度加剧;在1M NaCl+0.3M H2O2溶液中,合金的腐蚀电流较大,点蚀更为严重。
[Abstract]:7072Al alloy is an important heat transfer material, which is widely used in heat exchangers. The effects of Zn content on the microstructure, mechanical properties and electrochemical properties of the simulated brazed and annealed 7072Al alloys were systematically studied by electrochemical measurement. Increasing the content of Zn can promote the precipitation of precipitated phase in 7072Al alloy, and when the content of Zn is 1.3, the effect of promoting precipitation is the most obvious, and the content of Zn is further increased. The results of mechanical experiments show that Zn element can improve the mechanical properties of 7072Al alloy, and the yield strength of 7072Al alloy increases with the increase of Zn content. The results of electrochemical experiments show that the increase of Zn content will make 7072Al alloy in 0.5 NaCl. The corrosion potential of NaCl and 1m NaCl 0.3 M H _ 2O _ 2 solutions shifted negatively, but when Zn content increased from 1.5% to 2.5, the corrosion potential shifted negatively. The corrosion potential of the alloy has no obvious change in the three solutions, and the effect of Zn addition on the corrosion potential of the alloy is no longer obvious, but for the annealed alloy, the effect of Zn on the corrosion potential of the alloy is not obvious. The precipitation phase density of 7072Al alloy with different Zn content is not different, so the yield strength, tensile strength and elongation of the alloy are similar. And the fracture mode of the alloy is ductile fracture. 7072Al 1.3Zn and 7072Al 1.5and Zn alloy in 0.5NaCl. The corrosion resistance of 3.5% NaCl and 1m NaCl 0.3 M H _ 2O _ 2 solution was similar to that of 7072Al 1.3Zn and 7072Al. 1. 5 Zn alloy. The corrosion potential of 7072Al 2.5and Zn alloy moves negatively, the corrosion current increases and the corrosion degree intensifies. In addition, for all alloys, with the increase of chloride concentration in NaCl solution. The pitting pits on the surface of the alloy are denser and the corrosion degree of the alloy is more severe. In 1m NaCl 0.3M H _ 2O _ 2 solution, the corrosion current of the alloy is larger and the pitting corrosion is more serious.
【学位授予单位】：上海交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG146.21

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