热机械加工对2099铝锂合金挤压材组织与抗腐蚀性能的影响

Effect of Thermo-Mechanical Processing on Microstructure and Corrosion Resistance of 2099 Al-Li Alloy Extrusions

采用金相组织观察、XRD分析、硬度和导电率测试等手段,研究了热机械加工(Thermo-Mechanical Processing,TMP)对2099铝锂合金挤压材组织、硬度、导电率、晶间腐蚀及剥落腐蚀性能的影响。结果表明:与经T83(540℃/2 h固溶、3%预压缩、121℃/14 h+181℃/48 h时效)热处理的2099铝锂合金挤压材相比,经TMP(540℃/2 h固溶、400℃/48 h过时效、约50%大应变变形、540℃/2 h再结晶/固溶)+(121℃/14 h+181℃/48 h时效)处理的2099铝锂合金挤压材发生了明显的再结晶,硬度(HV)降低(从2006.2 MPa到1865.3 MPa),位错强化亦降低,但导电率和抗晶间腐蚀性能明显提高,同时抗剥落腐蚀性能也有所提高。结果表明,热机械加工是不显著降低2099铝锂合金挤压材硬度,但显著提高其抗晶间腐蚀性能的有效途径。

The effects of Thermo-Mechanical Processing（TMP） on microstructure, hardness, electricity, intergranular and exfoliation corrosion resistance of extruded 2099 Al-Li alloy were investigated by microstructure observation, XRD analysis, hardness and electric conductivity testing. The results show that compared with the extruded 2099 A1-Li alloy after T83 heat treatment （540 ℃/2 h solid solution, 3% pre-compression, 121 ℃/14 h ＋ 181 ℃/48 h aging）, the samples after TMP （540 ℃/2 h solid solution, 400 ℃/48 h overaging, about 50% large strain deformation, 540 ℃/2 h solid solution）＋（121 ℃/14 h ＋ 181 ℃/48 h aging） recrystallize obviously. The HV hardness is a little lower（2006.2 MPa vs 1865.3 MPa） and so is dislocations strengthening. The electric conductivity and the intergranular corrosion resistance are improved significantly and the exfoliation corrosion resistance is also enhanced. This study shows that TMP is an effective method to improve the intergranular resistance with the hardness not greatly reduced.