【摘要】 通过单轴超塑性拉伸试验,研究细晶1420铝锂合金在440℃~500℃温度范围和1×10-4s-1~1×10-2s-1初始应变速率范围内的超塑性变形行为,揭示其变形性能与工艺参数的相关性。结果表明,细晶1420铝锂合金超塑变形真应力-真应变曲线呈现两种典型的流变特征,即当变形初始应变速率低于0.0003s-1时,表现为稳态型;当初始应变速率高于0.0003s-1时,以软化型为主,且随着变形温度的升高和应变速率的降低,峰值应力降低。合金的最佳超塑性变形条件为480℃、1×10-4s-1,在该条件下,延伸率达到550%。随着应变速率的升高,延伸率降低;随变形温度的升高,延伸率则呈先升高后降低的趋势。利用多试样法进行线性拟合,获得试验条件下细晶1420铝锂合金的应变速率敏感性指数m值在0.41~0.48范围内,超塑变形激活能Q在43.5kJ/mol~79.7kJ/mol范围内。更多还原

【Abstract】 The superplastic deformation behavior,the relation between deformation properties and parameters of fine grained 1420 Al-Li alloy were investigated at a temperature range of 440℃~500℃ and at an initial strain rate range of 1×10-4s-1~1× 10-2s-1.The results indicated that the true stress-true strain curves of superplastic deformation showed steady-state type while the initial strain rate was under 3×10-4s-1,but it was softing type while the initial strain rate was over 3×10-4s-1.The peak stress reduced with the temperature increasing and strain rate decreasing.The optimum superplastic deformation was obtained at the temperature of 480℃and the initial strain rate of 1×10-4s-1,while the maximum elongation reached 550%.The elongation increased with initial strain rate decreasing,but it increased firstly and then decreased with temperature rising.Through multiple-sample method and linear-fitting,the strain rate sensitivity index m was 0.41~0.48,and the activation energy Q was 43.5kJ/mol~79.7kJ/mol.更多还原