时效时间对7150铝合金组织和性能的影响

通过维氏硬度测试、电导率测试和拉伸、晶间腐蚀等测试方法,研究了预时效、回归及再时效三个阶段中的时效时间对7150铝合金组织和性能的影响,借助透射电镜观察时效处理各阶段合金的微观组织演变。结果表明:120℃×20 h欠时效作为预时效工艺,比120℃×24 h峰时效的晶内析出相更细小,高温回归时更利于回溶。在190℃短时回归5、15和30 min中,15 min回溶效果最好,硬度最低,再经120℃×24 h再时效后合金抗拉强度Rm、屈服强度RP0.2、伸长率A分别为622 MPa、573 MPa、10.8%,显微硬度为204 HV,力学性能与120℃×24 h单级峰时效时相近。经120℃×20 h+190℃×15 min+120℃×24 h处理后7150铝合金综合性能好,耐晶间腐蚀性能佳。

Effect of aging time on microstructure and properties of 7150 aluminum alloy

The effects of aging time on microstructure and properties of 7150 aluminum alloy in three stages of pre-aging, regression and re-aging were studied by means of Vickers hardness test, electrical conductivity test and tensile test and intergranular corrosion. The results show that the size of the intragranular precipitation phase of the alloy after pre-aging at 120 ℃ for 20 h is smaller than that of after peak aging at 120 ℃ for 24 h, and is more favorable for re-dissolution when regression at high temperature. Among the short-time regression at 190 ℃ for 5, 15 and 30 min, the alloy has the best dissolution effect and the lowest hardness after regression for 15 min. After re-aging at 120 ℃ for 24 h, the tensile strength, yield strength, elongation of the alloy are 622 MPa, 573 MPa and 10.8%, respectively, the microhardness is 204 HV, and the mechanical properties are similar to that of single-stage peak aging at 120 ℃ for 24 h. After pre-aging at 120 ℃ for 20 h, then regression at 190 ℃ for 15 min and finally re-aging at 120 ℃ for 24 h, the 7150 aluminum alloy has good comprehensive properties and good intergranular corrosion resistance.