摘要
本文研究了90 mm厚度2195-T8铝锂合金不同厚度层和不同方向的拉伸力学行为、织构及时效析出相.结果表明:厚板纵向屈服强度最高,45°方向最低.纵向内层(T/2和3T/8层)屈服强度比外层(T/4和T/8层)高约40 MPa,而横向与45°方向不同厚度层的屈服强度差异很小.内层变形织构(Brass和S织构)较多,而外层再结晶织构含量较高.固溶体纵向预拉伸导致人工时效后变形织构晶粒中的高Schmid因子滑移系所在{111}面上T1相(Al2CuLi)密度较高;T8态时效合金纵向拉伸性能测试时,高Schmid因子滑移系所在{111}面与T1相高密度析出{111}面一致;而横向和45°方向拉伸性能测试时,这两种{111}面不完全一致.织构的不同导致了取向因子的差异和不同{111}面上T1相密度的差异,以上两种差异产生了协同作用,一方面导致纵向拉伸时内层屈服强度显著高于外层,另一方面也造成纵向的屈服强度高于横向和45°方向,以及合金纵向屈服变形后具有较低的应变硬化速率和较小的屈强差(抗拉强度与屈服强度的差值).
Abstract
The tensile mechanical behaviors,textures and aging precipitates of 90 mm thick 2195-T8 Al-Li alloy plate at different layer along different direction were investigated. The results show that the alloy possesses the highest yield strength (YS) along rolling direction (RD),but the lowest YS along 45° direction. Along RD,the internal layers (T/2 and 3T/8 layers) has YS 40 MPa higher than the outer layers (T/4 and T/8 layers). However,along 45° direction and transverse direction (TD),there exist little difference in the YS between different layers. The internal layer possesses more deformation textures,the outer layer possesses more recrystallization texture. Due to pre-strain performed on the solid solution along RD,there exists denser T1 precipitate (Al2CuLi) on the {111} slip face with high Schmid factor in the internal layer grains with deformation texture after aging. During the tensile test of the T8-aged alloy along RD,the {111} face of the slip system with high Schmid factor is consistent with the {111} face with high T1 precipitate density. However,during the tensile test along TD and 45° direction,these two types of {111} faces are not fully consistent in some texture grains. Due to the synergistic role of the orientation factor difference caused by texture and the T1 precipitate density difference on different {111} face,the internal layers along RD possesses much higher YS than the outer layers,the alloy also has higher YS,smaller strain hardening rate after yield deformation along RD,and lower difference between YS and UTS (ultimate tensile strength),than the TD and 45° directions.
维普
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