采用欠时效代替传统峰值时效处理,再结合低温回归处理,可获得良好的综合性能指标,采用透射电镜观察、拉伸及电导率测试等方法,研究RRA处理中预时效处理对低温回归和再时效后喷射成形7075合金组织与性能的影响。结果表明:采用120℃、16 h的欠时效预处理比120℃、24 h峰值时效预处理更有利于合金在160℃低温回归过程中晶内析出相的回溶,并且晶界相粗化、断开,合金抗腐蚀性能改善。欠时效预处理的合金经低温RRA处理后,其抗拉强度、屈服强度、伸长率和电导率分别为773 MPa、724 MPa、8.8%和37.2%(IACS),力学性能均高于T6峰值时效和传统低温与高温RRA的水平,且耐蚀性能也接近传统高温RRA制备小尺寸试样的,此工艺更适用于大型件的工业化热处理。
The effects of low-temperature retrogression in RRA on the microstructure, mechanical and conductivity properties of spray formed 7075 aluminum alloy with different pre-aging treatments were investigated by transmission electron microscopy, extension and conductivity tests. The results show that, pre-aging treatment (at 120℃for 16 h) is more beneficial for the re-dissolution of precipitates in matrix than peak aging (T6, at 120℃ for 24 h) at low-temperature (160℃) retrogression, and the grain boundary precipitates are interrupted after RRA treatment. After pre-aging at 120℃ for 16 h and RRA treatment, the tensile strength, yield strength, elongation and conductivity of the alloy are 773 MPa, 724 MPa, 8.8% and 37.2%(IACS), respectively. The mechanical properties are higher than those after T6 or conventional RRA treatment (neither low-temperature or high-temperature) and the conductivity is close to the small sample after conventional high-temperature RRA treatment. This process is fitted for large workpiece in industrial heat treatment.
参考文献
[1] | T. Hu;K. Ma;T.D. Topping.Precipitation phenomena in an ultrafine-grained Al alloy[J].Acta materialia,20136(6):2163-2178. |
[2] | 张纪帅;陈志国;任杰克;陈继强;魏祥;方亮.新型热机械处理对Al-Zn-Mg-Cu合金显微组织与性能的影响[J].中国有色金属学报,2015(4):910-917. |
[3] | 湛利华;贾树峰;张姣.电脉冲时效对7075铝合金组织和性能的影响[J].中国有色金属学报,2014(3):600-605. |
[4] | George, S.L.;Knutsen, R.D..Composition segregation in semi-solid metal cast AA7075 aluminium alloy[J].Journal of Materials Science,201211(11):4716-4725. |
[5] | M. JEYAKUMAR;S. KUMAR;G. S. GUPTA.Microstructure and Properties of the Spray-Formed and Extruded 7075 Al Alloy[J].Materials and Manufacturing Processes,20107/9(7/9):777-785. |
[6] | 刘斌;汪明朴;雷前;段雨露;刘林贤;虞红春.喷射沉积法制备Al-Zn-Mg-Cu-Zr合金的显微组织与性能[J].中国有色金属学报,2015(7):1773-1780. |
[7] | G. Silva;B. Rivolta;R. Gerosa;U. Derudi.Study of the SCC Behavior of 7075 Aluminum Alloy After One-Step Aging at 163℃[J].Journal of Materials Engineering and Performance,20131(1):210-214. |
[8] | R.E. RICKER;E.U. LEE;R. TAYLOR.Chloride Ion Activity and Susceptibility of Al Alloys 7075-T6 and 5083-H131 to Stress Corrosion Cracking[J].Metallurgical and Materials Transactions, A. Physical Metallurgy and Materials Science,20133(3):1353-1364. |
[9] | Hamidreza Fooladfar;Babak Hashemi;Mousa Younesi.The Effect of the Surface Treating and High-Temperature Aging on the Strength and SCC Susceptibility of 7075 Aluminum Alloy[J].Journal of Materials Engineering and Performance,20106(6):852-859. |
[10] | Eric M. Arnold;Joel J. Schubbe;Patrick J. Moran;Robert A. Bayles.Comparison of SCC Thresholds and Environmentally Assisted Cracking in 7050-T7451 Aluminum Plate[J].Journal of Materials Engineering and Performance,201211(11):2480-2486. |
[11] | 孙擎擎;董朋轩;孙睿吉;陈启元;陈康华.时效制度对挤压Al-6.2Zn-2.3Mg-2.3Cu铝合金电化学腐蚀性能的影响[J].中国有色金属学报,2015(4):866-874. |
[12] | 李荣德;苏睿明;曲迎东.喷射成形7075合金回归再时效处理的组织和抗应力腐蚀性能[J].机械工程学报,2013(20):22-29. |
[13] | Peng, G.;Chen, K.;Chen, S.;Fang, H..Influence of repetitious-RRA treatment on the strength and SCC resistance of Al-Zn-Mg-Cu alloy[J].Materials Science & Engineering, A. Structural Materials: Properties, Misrostructure and Processing,201112(12):4014-4018. |
[14] | Reda Y;Abdel-Karim R;Elmahallawi I.Improvements in mechanical and stress corrosion cracking properties in Al-alloy 7075 via retrogression and reaging[J].Materials Science & Engineering, A. Structural Materials: Properties, Misrostructure and Processing,20081/2(1/2):468-475. |
[15] | 黄兰萍;陈康华;李松;宋旼.高温预析出后7055铝合金局部腐蚀性能和时效硬化[J].稀有金属材料与工程,2007(9):1628-1633. |
[16] | 宋丰轩;张新明;刘胜胆;韩念梅;花隆.时效对7050铝合金预拉伸板抗腐蚀性能的影响[J].中国有色金属学报,2013(3):645-651. |
[17] | Wang, D;Ni, DR;Ma, ZY.Effect of pre-strain and two-step aging on microstructure and stress corrosion cracking of 7050 alloy[J].Materials Science and Engineering. A, Structural Materials: Properties, Microstructure and Processing,20081/2(1/2):360-366. |
[18] | H. JIANG;R. G. FAULKNER.MODELLING OF GRAIN BOUNDARY SEGREGATION, PRECIPITATION AND PRECIPITATE-FREE ZONES OF HIGH STRENGTH ALUMINIUM ALLOYS--I. THE MODEL[J].Acta materialia,19965(5):1857-1864. |
[19] | H. JIANG;R. G. FAULKNER.MODELLING OF GRAIN BOUNDARY SEGREGATION, PRECIPITATION AND PRECIPITATE-FREE ZONES OF HIGH STRENGTH ALUMINIUM ALLOYS--II. APPLICATION OF THE MODELS[J].Acta materialia,19965(5):1865-1871. |
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