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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。
Hot tensile creep is a new technology for processing difficult-to-shape thin-wall metal blanks at room temperature. Four factors and three levels of orthogonal table were used to optimize the four process parameters of Ti-6Al-4V hot-tensile creep Ti-6Al-4V sheet: temperature, tensile rate, elongation and holding time. The results of orthogonal test show that temperature is the most important factor affecting the rebound angle. The yield stress of the deformed material in the 0 ° direction along the tensile direction increases, and the yield stress in the directions of 45 ° and 90 ° around the undeformed material is small Range fluctuations. After hot tensile creep forming, the a phase in the deformed material changes from short and fine grains to long and thin grains, and the microhardness of the deformed material changes little before and after forming. Based on the results of orthogonal analysis and the analysis of the microstructure of the material, the optimum technological parameters of hot-tensile creep composite forming are obtained as follows: the temperature is 700 ° C, the stretching rate is 5 mm / min, 2% rate, holding time 8 min.