高屈强铝硅合金组织和性能的研究
发布时间：2019-01-29 02:55
【摘要】：铝合金被用于船舶制造已有上百年的历史。随着造船业的发展,船舶轻量化越来越受重视,舰船材料对于铝合金材料的屈服强度和耐蚀性的要求越来越高。A357合金铸造性能优异,抗疲劳、抗腐蚀性能、气密性好,在航空航天、汽车工业已广泛使用。通过优化A357合金的成分和工艺,在不降低其耐蚀性的前提下提高屈服强度,具有非常重要的实用价值。本文研究了Si、Cu、Mg、Mn合金元素对金属型铸造铝硅合金屈服强度和耐蚀性能的影响。设计四因素三水平正交实验,综合各因素对合金屈服强度、延伸率和耐蚀性的影响,确定最优成分;分析了不同Sr浓度对优化成分合金的变质效果;通过金相显微镜、SEM观察合金的微观组织;研究了最优成分合金的最佳时效工艺;观察合金的断口形貌并分析断裂机理;分析对比了最优成分合金和A357合金的耐腐蚀性。研究表明随着Si、Mg、Cu元素浓度的升高,合金的屈服强度增大;随着Si元素浓度的升高,合金的延伸率减小,耐蚀性先略微减弱后增强;随着Cu元素浓度的升高,耐蚀性显著减弱;优化后的成分为Si:8.3 wt.%,Cu:0.1 wt.%,Mg:1.0 wt.%,Mn:0.1 wt.%。0.06 wt.%Sr对最优成分合金中的硅具有良好的变质和细化效果;热处理后硅相呈颗粒状分布在基体中,粒度在5μm左右;富锰相呈细小颗粒状分布;Cu、Mg元素主要以弥散的脱溶相的形式分布在基体中;过变质的铝合金晶界元素富集严重,延伸率很低。最优成分的合金的最佳时效工艺为时效温度170℃时,时效时间为8h;此工艺下合金的屈服强度为322.5MPa,延伸率3.2%,耐蚀性优于A357铝合金。不同成分的合金断口形貌均为穿晶韧性断口;硅含量不同对断口形貌影响显著,随着硅含量的升高,韧窝面积逐渐变小,深度逐渐变浅;基体中脆性相逐渐增多,撕裂棱也逐渐增多,合金塑性变差。
[Abstract]:Aluminum alloys have been used in shipbuilding for hundreds of years. With the development of shipbuilding industry, more and more attention has been paid to the lightening of ships, and the requirements of ship materials for the yield strength and corrosion resistance of aluminum alloy are higher and higher. A357 alloy has excellent casting performance, fatigue resistance, corrosion resistance and air tightness. In aerospace, the automobile industry has been widely used. By optimizing the composition and process of A357 alloy, it is of great practical value to improve the yield strength without reducing the corrosion resistance of A357 alloy. In this paper, the effect of Si,Cu,Mg,Mn alloy elements on the yield strength and corrosion resistance of Al-Si alloy in metal mold casting has been studied. The orthogonal experiment of four factors and three levels was designed to determine the optimum composition by synthesizing the effects of each factor on the yield strength, elongation and corrosion resistance of the alloy, and the modification effect of different Sr concentration on the alloy with optimized composition was analyzed. The microstructure of the alloy was observed by SEM; the optimum aging process of the alloy was studied; the fracture morphology of the alloy was observed and the fracture mechanism was analyzed; and the corrosion resistance of the optimum composition alloy and A357 alloy was analyzed and compared. The results show that the yield strength of the alloy increases with the increase of the concentration of Si,Mg,Cu element, the elongation of the alloy decreases with the increase of the concentration of Si element, and the corrosion resistance of the alloy decreases slightly and then increases with the increase of the concentration of Si element. The corrosion resistance decreased with the increase of Cu concentration. The optimized composition is Si:8.3 wt.%,Cu:0.1 wt.%,Mg:1.0 wt.%,Mn:0.1 wt.%.0.06 wt.%Sr, which has good modification and refinement effect on silicon in the optimal composition alloy. After heat treatment, the silicon phase is granular in the matrix, the particle size is about 5 渭 m, the manganese rich phase is a fine granular distribution, and the Cu,Mg element is mainly distributed in the matrix in the form of dispersive desolvent phase. The overmodified aluminum alloy is rich in grain boundary elements and its elongation is very low. The best aging process of the alloy with the optimum composition is that the aging temperature is 170 鈩，
本文编号：2417568
[Abstract]:Aluminum alloys have been used in shipbuilding for hundreds of years. With the development of shipbuilding industry, more and more attention has been paid to the lightening of ships, and the requirements of ship materials for the yield strength and corrosion resistance of aluminum alloy are higher and higher. A357 alloy has excellent casting performance, fatigue resistance, corrosion resistance and air tightness. In aerospace, the automobile industry has been widely used. By optimizing the composition and process of A357 alloy, it is of great practical value to improve the yield strength without reducing the corrosion resistance of A357 alloy. In this paper, the effect of Si,Cu,Mg,Mn alloy elements on the yield strength and corrosion resistance of Al-Si alloy in metal mold casting has been studied. The orthogonal experiment of four factors and three levels was designed to determine the optimum composition by synthesizing the effects of each factor on the yield strength, elongation and corrosion resistance of the alloy, and the modification effect of different Sr concentration on the alloy with optimized composition was analyzed. The microstructure of the alloy was observed by SEM; the optimum aging process of the alloy was studied; the fracture morphology of the alloy was observed and the fracture mechanism was analyzed; and the corrosion resistance of the optimum composition alloy and A357 alloy was analyzed and compared. The results show that the yield strength of the alloy increases with the increase of the concentration of Si,Mg,Cu element, the elongation of the alloy decreases with the increase of the concentration of Si element, and the corrosion resistance of the alloy decreases slightly and then increases with the increase of the concentration of Si element. The corrosion resistance decreased with the increase of Cu concentration. The optimized composition is Si:8.3 wt.%,Cu:0.1 wt.%,Mg:1.0 wt.%,Mn:0.1 wt.%.0.06 wt.%Sr, which has good modification and refinement effect on silicon in the optimal composition alloy. After heat treatment, the silicon phase is granular in the matrix, the particle size is about 5 渭 m, the manganese rich phase is a fine granular distribution, and the Cu,Mg element is mainly distributed in the matrix in the form of dispersive desolvent phase. The overmodified aluminum alloy is rich in grain boundary elements and its elongation is very low. The best aging process of the alloy with the optimum composition is that the aging temperature is 170 鈩，
本文编号：2417568
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