摘要
采用硬度计、数字涡流金属电导仪、透射电镜(TEM)、万能拉伸试验机、扫描电镜(SEM)等对Al-6.8Zn-2.3Mg-2.0Cu-0.15Sc合金在高温回归再时效(RRA)过程中的性能与组织演变规律进行研究。结果表明:合金在170℃回归时,具有较高硬度与优良的抗电化学腐蚀性能,合金170℃回归1 h时主相η'细小弥散数量众多,在形变过程中借助位错切过与Orowan机制强化合金,强度可达625.1 MPa,伸长率达9.6%,获得了优于单级时效(T6)G.P.区强化达到的强度592.4 MPa、伸长率6.5%,强度提高32.7 MPa,伸长率提高47.7%,拉伸断口形貌SEM显示为完全的韧性断裂特征。Al-6.8Zn-2.3Mg-2.0Cu-0.15Sc合金的优秀RRA工艺为140℃×24 h+170℃×1 h+160℃×24 h。
Properties and microstructure evolution laws of Al-6.8Zn-2.3Mg-2.0Cu-0.15Sc alloy in the process of high-temperature retrogression and re-aging(RRA)were studied via technological means such as sclerometer,digital eddy current metal conductometer,transmission electron microscope(TEM),universal tensile testing machine and scanning electron microscope(SEM).The results show that in the retrogressive process at 170℃the alloy has high hardness and excellent electrochemical corrosion resistance.The principal phaseη'of the alloy is fine,dispersed and numerous after the retrogressive process at 170℃for 1 h,and it strengthens the alloy with Orowan mechanism by virtue of dislocation cutting in the process of deformation.Therefore,it achieves the strength of 625.1 MPa and the elongation of 9.6%,and is superior to one-step aging(T6)G.P.area with the strength of 592.4 MPa and the elongation of 6.5%.The strength is enhanced by 32.7 MPa and the elongation is increased by 47.7%.In addition,the appearance of tensile fracture presentes a complete ductile fracture characteristic via SEM.The excellent RRA process of the Al-6.8Zn-2.3Mg-2.0Cu-0.15 Sc alloy is aging at 140℃for 24 h,regression aging at 170℃for 1 h and re-aging at 160℃for 24 h.
作者
史文杰
王春华
Shi Wenjie;Wang Chunhua(College of Engineering,Yantai Nanshan University,Yantai Shandong 265713,China)
出处
《金属热处理》
CAS
CSCD
北大核心
2020年第7期63-67,共5页
Heat Treatment of Metals
基金
山东省重点研发计划(2017GGX20130)
山东省高等学校科技计划(J18KB046)。
关键词
高温回归再时效
导电率
强化机制
high-temperature retrogression and re-aging
electrical conductivity
strengthening mechanism
