摘要
Hot stretch-creep forming （SCF） is a novel technique to produce hard-to-form thin-walled metal components. Comprehensively considering the analysis results of the springback angle, yield strength and microstructure, four hot SCF process parameters including temperature, stretch velocity, post stretch percentage and dwelling time of a Ti-6Al-4V alloy sheet were optimized using an orthogonal experiment. The results reveal that temperature is the most important factor on springback angle. The yield strength of the deformed material in 0° direction increases, while those in directions of 45° and 90° fluctuate around the original value. After hot SCF, the shape of some a phases changes from short thin grains to long slender ones, and the microhardness changes very little. The optimized parameters with temperature of 700 ℃, stretch velocity of 5 mm/min, post stretch percentage of 2% and dwelling time of 8 min are achieved finally.
热拉伸蠕变是一种加工常温难成形薄壁金属坯料的新技术。采用四因素、三水平正交表,优化了热拉伸蠕变Ti-6Al-4V板材的4个工艺参数:温度、拉伸速率、补拉伸量和保温时间。正交试验结果表明:温度是影响回弹角的最重要因素;沿拉伸方向成0°方向的变形材料屈服应力增加,沿45°和90°方向的屈服应力围绕未变形材料的屈服应力小范围波动。经过热拉伸蠕变成形,变形材料微观组织中a相由短细晶粒变成长细晶粒,变形材料显微硬度在成形前后变化很小。综合回弹角、屈服强度指标正交分析结果和材料微观组织变化情况,得出了热拉伸蠕变复合成形的优化工艺参数为:温度700°C,拉伸速率5 mm/min,补拉率2%,保温时间8 min。
基金
Project(51175022)supported by the National Natural Science Foundation of China
Project(51318040315)supported by the National Defense Pre-research of China
Project(09000114)supported by Initial Funding for the Doctoral Program of BIGC
Project(E-a-2014-13)supported by BIGC Key Project
