(沈陽工業(yè)大學(xué) 材料科學(xué)與工程學(xué)院，沈陽 110870)
摘 要: 采用欠時效代替?zhèn)鹘y(tǒng)峰值時效處理，再結(jié)合低溫回歸處理，可獲得良好的綜合性能指標(biāo)，采用透射電鏡觀察、拉伸及電導(dǎo)率測試等方法，研究RRA處理中預(yù)時效處理對低溫回歸和再時效后噴射成形7075合金組織與性能的影響。結(jié)果表明：采用120 ℃、16 h的欠時效預(yù)處理比120 ℃、24 h峰值時效預(yù)處理更有利于合金在160 ℃低溫回歸過程中晶內(nèi)析出相的回溶，并且晶界相粗化、斷開，合金抗腐蝕性能改善。欠時效預(yù)處理的合金經(jīng)低溫RRA處理后，其抗拉強度、屈服強度、伸長率和電導(dǎo)率分別為773 MPa、724 MPa、8.8%和37.2%(IACS)，力學(xué)性能均高于T6峰值時效和傳統(tǒng)低溫與高溫RRA的水平，且耐蝕性能也接近傳統(tǒng)高溫RRA制備小尺寸試樣的，此工藝更適用于大型件的工業(yè)化熱處理。
關(guān)鍵字: 7075鋁合金；噴射成形；再時效；低溫回歸；預(yù)時效；電導(dǎo)率
（School of Materials Science and Engineering, Shenyang University of Technology, Shenyang 110870, China）
Abstract: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.
Key words: 7075 Al alloy; spray forming; re-aging; low-temperature retrogression; pre-aging; conductivity
