连续定向凝固铜棒及其冷加工后的组织和力学性能

研究了连续定向凝固铜棒及对其进行大变形量冷加工后的线材的微观组织和力学性能。凝固铜棒具有纵向连续柱状晶组织,塑性优异,伸长率达到50．5%。经过冷轧和冷拔,柱状晶组织细化为纤维晶组织,并产生显著的加工硬化。经过真应变为3．6的冷变形加工,其抗拉强度由未变形的140MPa提高到418MPa,伸长率则下降了近70％。断口形貌观察表明：凝固铜棒、轧制后的铜杆及拉拔后的铜线都是穿晶韧性断裂．其微观断口均呈山峰状,且峰顶依次逐渐尖锐。

Microstructure and Mechanical Properties of Continuous Unidirectional Solidification Copper Bar and Cold Processed Wires

The microstructure and mechanical properties of continuous unidirectional solidification copper bar and succedent cold processed wires were investigated. The longitudinal microstructure of the copper bar is columnar crystals and the bar exhibits excellent plasticity with the tensile elongation attaining 50.5%. After cold rolled and drawn, the columnar crystals fined to fibrous crystals, which resulted in remarkable work hardening. At a true processing strain of 3.6, the tensile strength of the copper wires increased to 418MPa from 140MPa of the as-cast bar, while the elongation decreased by about 70%. The fracture morphology of the bar and succedent cold processed wires are all transgranular ductile fracture, and the micro-fracture is peak-like, gradually sharpening with increase of strain.