Al-5Ti-1B细化剂作用下半固态7A04铝合金组织与性能研究
发布时间：2018-10-18 20:09
【摘要】：Al-Zn-Mg-Cu(7xxx系列)系铝合金由于具有低密度、高强度、高塑性等优点,广泛应用于轨道交通和航空航天领域,但该类合金常规铸造时容易产生热裂等缺陷,使其难以通过常规铸造方式直接生产高性能零件。本文系统地研究了 7A04铝合金流变成形中的半固态浆料制备、压铸成形及铸件热处理,以期为实现7A04铝合金流变成形工业生产奠定基础。本文通过对添加Al-5Ti-1B细化剂制备的7A04铝合金半固态浆料组织的分析,系统的研究了 Al-5Ti-1B细化剂添加量对初生α-Al颗粒及后续二次凝固产生的α2和α3颗粒的平均尺寸和圆整度的影响规律,同时研究了 Al-5Ti-1B细化剂对铝合金半固态浆料组织径向均匀性的影响。结果表明:添加Al-5Ti-1B细化剂可以明显改善7A04铝合金半固态浆料初生α-Al颗粒和α2颗粒,但对α3颗粒尺寸和圆整度及7A04铝合金物相无显著影响。在浆料温度630℃下,添加0.1%的Al-5Ti-1B细化剂制备的7A04铝合金半固态浆料的初生α-Al颗粒和α2颗粒的平均直径和圆整度分别为71μm和0.49、29μm和0.45。当Al-5Ti-1B细化剂的添加量超过0.1%,随着细化剂添加量的增加,细化效果无明显提高。添加Al-5Ti-1B细化剂可以改善7A04铝合金半固态浆料组织在径向上的均匀性,在635℃下,变异系数Cv为2.8%。本文通过对添加不同量的Al-5Ti-1B细化剂的7A04铝合金熔体进行压铸,系统的研究了在压铸温度、细化剂添加量和压射速度对铸件的初生α-Al颗粒及二次凝固组织、铸件内部的孔隙率及力学性能的影响。结果表明:添加A1-5Ti-1B可以细化圆整铸件的初生α-Al颗粒,细化圆整效果在压铸温度635℃时最明显;随着Al-5Ti-1B添加量的增多,细化效果无明显提高;Al-5Ti-1B添加量对铸件的孔隙率及力学性能的影响不明显。压铸温度分别为720℃和660℃时,铸件的颗粒尺寸随压射速度的增大无明显变化,圆整度略有提高;压铸温度为635℃时,7A04铝合金铸件的初生α-Al颗粒尺寸随压射速度的增大而减小,圆整度明显提高。铸件的二次凝固组织中α2颗粒平均尺寸和圆整度随压射速度的增大无明显变化。压铸温度相同,7A04铝合金压铸件的孔隙率、密度及抗拉强度和延伸率都是在速度控制阀第四圈时最优;压射速度相同时,铸件的孔隙率随压铸温度的降低而减小,而密度及力学性能增大。本文通过对添加Al-5Ti-1B细化剂的7A04铝合金压铸件进行热处理,研究了在不同压铸温度下、不同Al-5Ti-1B添加量下热处理对该合金压铸件内部的孔隙率及力学性能的影响。结果表明:Al-5Ti-1B添加量的增加对热处理后的铸件的孔隙率及力学性能无明显影响。热处理后的铸件与未热处理相比,孔隙率略微增加,密度略微减小,但抗拉强度和延伸率明显提高,最大值分别为391MPa和2.5%,但由于孔洞的存在,铸件的力学性能与锻件相比还有很大的差距。
[Abstract]:Al-Zn-Mg-Cu (7xxx series) aluminum alloys are widely used in rail transit and aerospace fields because of their advantages of low density, high strength and high plasticity. It is difficult to produce high performance parts directly by conventional casting. In this paper, the preparation of semi-solid slurry, die casting and heat treatment of 7A04 aluminum alloy rheological forming are studied systematically, in order to lay a foundation for the industrial production of 7A04 aluminum alloy rheological forming. In this paper, the microstructure of semi-solid slurry of 7A04 aluminum alloy prepared by adding Al-5Ti-1B refiner was analyzed. The effects of the addition of Al-5Ti-1B refiner on the average size and roundness of primary 伪 Al particles and 伪 2 and 伪 3 particles produced by subsequent secondary solidification were studied systematically. At the same time, the effect of Al-5Ti-1B refiner on the radial uniformity of aluminum alloy semi-solid slurry was studied. The results show that the addition of Al-5Ti-1B refiner can obviously improve the primary 伪-Al and 伪 2 particles of 7A04 aluminum alloy semi-solid slurry, but has no significant effect on the size and roundness of 伪 3 particles and the phase of 7A04 aluminum alloy. At 630 鈩，
本文编号：2280234
[Abstract]:Al-Zn-Mg-Cu (7xxx series) aluminum alloys are widely used in rail transit and aerospace fields because of their advantages of low density, high strength and high plasticity. It is difficult to produce high performance parts directly by conventional casting. In this paper, the preparation of semi-solid slurry, die casting and heat treatment of 7A04 aluminum alloy rheological forming are studied systematically, in order to lay a foundation for the industrial production of 7A04 aluminum alloy rheological forming. In this paper, the microstructure of semi-solid slurry of 7A04 aluminum alloy prepared by adding Al-5Ti-1B refiner was analyzed. The effects of the addition of Al-5Ti-1B refiner on the average size and roundness of primary 伪 Al particles and 伪 2 and 伪 3 particles produced by subsequent secondary solidification were studied systematically. At the same time, the effect of Al-5Ti-1B refiner on the radial uniformity of aluminum alloy semi-solid slurry was studied. The results show that the addition of Al-5Ti-1B refiner can obviously improve the primary 伪-Al and 伪 2 particles of 7A04 aluminum alloy semi-solid slurry, but has no significant effect on the size and roundness of 伪 3 particles and the phase of 7A04 aluminum alloy. At 630 鈩，
本文编号：2280234
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