多向锻造2099铝锂合金挤压材的组织和性能

Microstructure and Property of Multi-Directional Forged 2099 Al-Li Alloy Extrusions

2099铝锂合金因其良好的综合性能广泛应用于航空航天领域。将2099铝锂合金挤压材棒料进行540℃/2 h固溶水淬处理和400℃/24h过时效处理后,对其进行6道次多向锻造。经过540℃/2 h固溶和121℃/14 h+181℃/66 h时效处理后,采用金相显微镜(OM)观察,电子背散射衍射(EBSD)分析,晶间腐蚀及剥落腐蚀实验和拉伸性能测试,研究多向锻造对2099铝锂合金挤压材的组织和性能的影响。结果表明:多向锻造可以有效地改善2099铝锂合金挤压材组织的方向性,多向锻造后组织方向性已明显减弱,沿轴向方向的带状组织消失;并且细化合金晶粒,晶粒尺寸由5004.49 nm降低到2808.59 nm;提高了合金强度,使抗拉强度由418.85 MPa提高到550.649 MPa,并且各个方向的拉伸性能一致;还使合金具有较好的抗腐蚀性能,抗晶间腐蚀等级为2级,抗剥落腐蚀等级为PA^PB级,并且在各个方向上的抗腐蚀性能处于同一等级,不存在方向差异性。

2099 Al-Li alloy is widely used in the aerospace field for its excellent performance. 6 passes multi-directional forging was taken to 2099 Al-Li alloy extrusion samples after a pretreatment of 540 ℃ /2 h solid solution and 400 ℃ /24 h over-aging treatment. After 540 ℃ /2 h solid solution and 121 ℃ /14 h ＋ 181 ℃ /66 h aging treatment,the influences of multi-directional forging on the microstructure and property of 2099 Al-Li alloy extrusion were studied by optical microscrope（ OM） observation,electron backscattered diffraction（ EBSD） analysis,inter-granular corrosion resistance and exfoliation corrosion resistance experiments and tensile test. The results showed that multi-directional forging could refine the directivity of the extrusions,in which the directional texture was significantly weakened,and the band structure disappeared in the axial direction after multi-directional forging. Besides,the grain was refined,the grain size reduced from 5004. 49 to 2808. 59 nm; tensile strength was improved with the extension strength increasing from 418. 85 to550. 649 MPa; the alloy was kept in a high corrosion resistance level,that was,the inter-granular corrosion resistance was in Level 2and the exfoliation corrosion resistance was in Levels PA － PB; and the corrosion resistances of each direction were in the same level with few differences.