预拉伸变形量对2050铝锂合金组织和性能的影响

通过拉伸试验、晶间腐蚀试验以及透射电镜(TEM)等方法对固溶处理后不同预拉伸变形量处理并人工时效后2050铝锂合金厚板室温拉伸性能、抗晶间腐蚀性能以及合金的微观组织形貌进行了研究。结果表明,随预拉伸变形量的增加,合金L向和LT向的屈服强度和抗拉强度逐渐增大,变形量＞4.0%后趋于平稳,伸长率逐渐降低后趋于稳定;随预拉伸变形量增加,腐蚀形貌由晶间腐蚀变为点蚀,点蚀深度逐渐减小。预拉伸变形促进了人工时效过程中晶内T₁相的弥散析出,降低了晶界处T₁相含量,因此提高了合金的强度和抗晶间腐蚀性能。预拉伸变形量为5.0%时,合金的强度和抗晶间腐蚀性能最佳。

Effect of pre-stretching amount on microstructure and properties of 2050 Al-Li alloy

Effect of pre-stretching processing after solution treatment on tensile properties, intergranular corrosion resistance and microstructure of the artificial aged 2050 Al-Li alloy were studied by means of tensile test, intergranular corrosion test and transmission electron microscope(TEM). The results show that the yield strength and ultimate tensile strength at L and LT directions of the 2050 Al-Li alloy increase gradually with the increase of pre-stretching amount, and tend to be stable when the pre-stretching amount is over 4.0%, elongation decreases rapidly at first and then finally keep stable. With the increase of pre-stretching amount, the corrosion morphology changes from intergranular corrosion to pitting, and the pitting depth decreases gradually. The pre-stretching processing promotes the T₁ phase precipitation in the grains and makes its distribution more dispersive and homogeneous, while the precipitation at grain boundary is restrained during the artificial aging, which consequently improves the tensile strength and the intergranular corrosion resistance. When the pre-stretching amount is 5.0%, the optimum tensile strength and intergranular corrosion resistance is obtained for the alloy.