含铒铝合金TIG焊接头组织与性能

Microstructure and properties of Er-containing aluminum alloy TIG weld joints

关键词:  初生相  次生相  细晶强化  析出强化

Key words:  primary phase  secondary phase  fine-grain strengthening  precipitation strengthening

摘要:

为了研究Er元素对焊缝的强化作用及机理,对含Er元素铝合金进行TIG重熔焊试验,通过对接头组织结构观察和力学性能测试,发现在焊缝的晶界处有初生Al₃Er相析出,但与母材相比析出相数量较少,在晶界处未形成连续的环状,次生Al₃Er相在焊缝中也有析出,但数量极少,Er元素将以固溶态和偏析的形式存在.Er元素对焊接接头的强化作用主要以初生相Al₃Er粒子的细晶强化为主,而次生相对位错和亚晶界的钉扎作用很小.结果表明,Er元素对焊缝的强化作用有限,焊接接头力学性能明显下降,焊接接头的抗拉强度为297 MPa,是母材强度的72%,拉伸断裂位置主要是分布在焊缝中心或熔合区附近.

Abstract:

To study the strengthening effect and mechanism of Er element on the weld, the remelting welding of Al-Mg alloy with Er was adopted, and the organizational structure and mechanical properties of the joint were observed. The results show that there is primary Al₃Er phase precipitation on the grain boundaries in weld, but the quantity of it is fewer than that of in the base material, and the precipitation doesn't form a continuous ring. The secondary Al₃Er precipitation also can be found in the welding, but the precipitation phase quantity is very few. Er elements will presence in the solid solution or segregation way. The strength of Er element on the weld joint is mainly based on the primary Al₃Er to refine the grain. The effect of the secondary phase on the weld joint is small, and so the weld joint mechanical properties decrease evidence. The tensile strength of welded joints is 297 MPa, and the strength coefficient of welded joints is 72% of base material. Tensile fracture position is mainly in the center of the weld and near the fusion zone.