稀土变质处理对高性能铸造铝合金影响的研究

发布时间：2018-03-03 08:28

本文选题：Al-Zn-Mg-Cu　切入点：稀土　出处：《沈阳大学》2015年硕士论文　论文类型：学位论文

【摘要】：Al-Zn-Mg-Cu系列合金与其他系列铝合金相比,具有强度高,密度低等许多优点,综合性能比较好,具有很好的应用前景。稀土元素添加到合金中很常见,但是关于在合金中复合添加Ce与Er的报道不多。本文将采用了扫描电镜(SEM)、万能试样拉伸机、金相显微镜(OM)等手段研究单独添加Ce与复合添加(Ce、Er)对铸态Al-Zn-Mg-Cu组织和性能的影响,探讨不同的稀土添加量对合金的作用。铸态合金经过均匀化后,进行冷轧,探究在不同的时效时间处理下,对冷轧后的合金组织和性能的影响。(1)稀土元素Ce对铸态Al-Zn-Mg-Cu组织在一定范围内很好的的细化作用,添加Ce的量为0.1%时,合金的晶粒开始细化,合金的综合力学性能开始提高;本实验添加0.2%细化的效果比较好,抗拉强度达到220MPa,硬度值达到72HRB;当继续添加到0.3%,晶粒开始变的粗大,力学性能下降,但比未添加时效果要好。(2)Ce和Er复合添加对铸态的Al-Zn-Mg-Cu组织也有很好的细化作用,复合添加Ce与Er的含量0.1%时,合金抗拉强度比未添加时提高了20.1%。本实验复合添加量为0.2%时细化效果较好,抗拉强度比单独添加稀土含量为0.2%Ce的合金提高了10.5%,延伸率提高了7.8%,硬度值提高了6.4%。(3)铸锭均匀化处理后,进行冷轧,冷轧过后进行420保温退火处理,再进行不同时间的时效处理,当时效时间为120/8h,合金的性能最好,硬度出现峰值。
[Abstract]:Compared with other series of aluminum alloys, Al-Zn-Mg-Cu series alloys have many advantages, such as high strength, low density and so on. However, there are few reports on the addition of ce and er in the alloy. In this paper, the effects of ce and ce on the microstructure and properties of as-cast Al-Zn-Mg-Cu are studied by means of scanning electron microscope (SEM), universal specimen drawing machine and metallographic microscope. The effects of different rare earth additions on the alloy were discussed. After homogenization, the as-cast alloy was rolled in cold, and the effect of different aging time was investigated. Effect of rare Earth element ce on the Microstructure and Properties of Cold rolled Alloy. The rare earth element ce has a good refining effect on the as-cast Al-Zn-Mg-Cu structure within a certain range. When the addition of ce is 0.1, the grain size of the alloy begins to refine and the comprehensive mechanical properties of the alloy begin to improve. In this experiment, the effect of adding 0.2% thinning is better, the tensile strength is 220 MPA, the hardness value is 72 HRB.When the addition of 0.2% is continued, the grain size becomes coarse and the mechanical properties decrease. But the effect is better than that without adding. The addition of ce and er can also refine the Al-Zn-Mg-Cu structure of as-cast state, and when the content of ce and er is 0.1%, the structure of as-cast Al-Zn-Mg-Cu can be further refined. The tensile strength of the alloy was increased by 20.1g than that of the alloy without addition. The tensile strength was increased by 10.5, the elongation by 7.8 and the hardness by 6.4. after the ingot was homogenized, the alloy was cold-rolled and annealed with 420 heat preservation after cold rolling, compared with the alloy with 0.2 RE content added alone, and the tensile strength was increased by 10.5%, the elongation of the alloy was increased by 7.8%, and the hardness value was increased by 6.44%. When the aging time is 120 / 8 h, the properties of the alloy are the best and the hardness peak.
【学位授予单位】：沈阳大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG146.21

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