一种高强度Ti-6Al-4V钛合金丝材制备工艺的研究

Investigation on Preparation Process for High Strength Ti-6Al-4V Wire

对不同氧含量的Ti-6Al-4V钛合金采用控温热拉拔试验,制得准1.0 mm、准2.0 mm、准2.5 mm三种不同规格的丝材,研究Ti-6Al-4V钛合金中氧含量及控温热拉拔制备方法对材料组织和力学性能的影响。分析结果表明:氧含量对Ti-6Al-4V钛合金轧制坯料金相有明显的影响,氧含量越高,α相的相对含量越多,准8.0 mm轧制坯料等轴α相的尺寸为2～5μm,拉拔成准2.0 mm后获得约0.5μm的超细晶粒;随着合金中氧含量的增加、拉拔规格的细化,丝材的力学性能提高,塑性下降;含氧0.14wt%的Ti-6Al-4V准2.0 mm丝材抗拉强度和塑性分别达到1270 MPa和12%,综合力学性能优良;进一步分析发现,Ti-6Al-4V丝材室温拉伸时发生沿等轴α相晶界的韧性断裂,超细晶粒及高密度位错是材料获得高强度的根本所在。

Ti-6Al-4V alloy wire with different oxygen content was prepared by control-temperature hot drawing test,the Ti-6Al-4V alloy wires of three diameters of φ1.0 mm,φ2.0 mm and φ2.5 mm were obtained,the effects of oxygen content and control-temperature hot drawing on microstructure and mechanical properties of the alloy were investigated.The results show that the oxygen content of the alloys has obvious effect on the microstructure of as-rolled Ti-6Al-4V alloy.The higher the oxygen content,the more the α phase.The as-rolled Ti-6Al-4V alloy with φ8 mm shows the equiaxed α grains of 2～5 μm.And then ultra-fine grains（0.5 μm） are obtained by drawing to φ2 mm.Furthermore,with the increase of oxygen content in the alloys and the decrease of diameter,the mechanical properties increase,but the plasticity decreases.φ2 mm Ti-6Al-4V alloy wire with oxygen 0.14wt% exhibits Rm=1270 MPa and A=12%.Further investigation shows that the fracture and cracks occur across the equiaxed α grain boundary of Ti-6Al-4V alloy.The ultra-fine grains and high density dislocation in Ti-6Al-4V alloy result in high strength.