电磁连铸和微合金化对5356铝合金组织性能的影响

The effects of the EMC technology and micro-alloying to 5356-Al alloy

摘要:

本文研究了不同电源功率、拉坯速率和冷却水量等参数以及微量Sc元素对5356铝合金组织和性能的影响。结果表明，在电源功率10kw，拉坯速率8cm/min，冷却水量1.7m3/h的工艺条件下，5356铝合金具有最优的表面和内部质量以及综合力学性能，抗拉强度、伸长率分别可达310.0MPa和16.3%，且铸锭表面无明显铸造缺陷，边部组织基本为等轴晶，心部组织呈破碎枝晶形态，第二相分布均匀。5356铝合金合理的均匀化处理工艺参数为440℃?30h，空冷，均匀化处理后合金元素Mg的微观偏析基本消除，在晶界连续分布的Al8Mg5相明显回溶。微量的Sc元素显著提高5356铝合金的强度和塑性。实验证明，5356-Al 0.4wt.%Sc合金晶粒明显细化，第二相数量减少，抗拉强度和伸长率达330.0MPa和29.0%，分别提高6.5%和77.9%。

Abstract:

The effects of the different power, casting rate, quantity of cooling water and trace amount of Sc to 5356-Al alloy are investigated. The experiment shows 5356-Al alloy has the optimal surface and internal quality and tensile properties with the process parameters which the power is 10kw, the casting speed is 8-9cm/ min, the quantity of cooling water is 1.7m3/h. The tensile strength and elongation of 5356-Al alloy can be up to 310.0MPa and 16.3%, and the surface has no obvious casting defects. At the same time, the microstructure of the edge is equiaxed crystals basically, while the center is broken dendrite crystals with an uniform distribution of the second phases. Besides, the homogenization heat-treatment of 5356-Al alloy has also been established: 440℃?30h with the air cooling. After the homogenization heat-treatment, the micro-segregation of Mg has been eliminated basically and the phase Al8Mg5 which is distributing along the grain boundaries continuously dissolves significantly. In addition, trace amount of Sc can significantly improve the strength and plasticity of 5356-Al alloy. The experiment proves 5356-Al 0.4wt. %Sc alloy can refine the grain size and reduce the number of the second phase, the tensile strength and elongation can be up to 330.0MPa and 29.0%, which increased by 6.5% and 77.9% respectively.