非等溫回歸再時(shí)效對(duì)Al-8Zn-2Mg-2Cu合金厚板組織及性能的影響非等溫回歸再時(shí)效對(duì)Al-8Zn-2Mg-2Cu合金厚板組織及性能的影響Effect of Non-isothermal Retrogression and Re-aging on Microstructure and Properties of Al-8Zn-2Mg-2Cu Alloy Thick Plate 基于鋁合金厚板熱處理時(shí)客觀存在的非等溫現(xiàn)象，利用非等溫回歸動(dòng)力學(xué)模型、力學(xué)性能測(cè)試、電導(dǎo)率測(cè)試及TEM觀察，研究了非等溫回歸溫度場(chǎng)和時(shí)間的耦合效應(yīng)對(duì)Al-8Zn-2Mg-2Cu(質(zhì)量分?jǐn)?shù)，%)合金厚板組織及性能的影響。結(jié)果表明，隨著非等溫回歸時(shí)間的延長(zhǎng)，合金的電導(dǎo)率逐漸升高，硬度和強(qiáng)度逐漸下降。優(yōu)化的非等溫回歸再時(shí)效制度使MgZn2相的尺寸分布范圍寬化。位錯(cuò)切過和位錯(cuò)繞過強(qiáng)化機(jī)制的合理匹配在小幅度犧牲強(qiáng)度的前提下顯著提升了合金的電導(dǎo)率。以105 ℃，24h為預(yù)時(shí)效制度，經(jīng)過慢速升溫非等溫回歸處理120 min后再經(jīng)120 ℃，24h峰時(shí)效，Al-8Zn-2Mg-2Cu鋁合金厚板的抗拉強(qiáng)度、屈服強(qiáng)度及電導(dǎo)率分別為620 MPa、593 MPa和21.1 M S/m，其綜合性能優(yōu)于單級(jí)峰時(shí)效(T6)及雙級(jí)過時(shí)效(T73)，且包含慢速升溫的非等溫回歸再時(shí)效技術(shù)更適用于厚板的時(shí)效熱處理。 7000 series Al alloy has attracted so many attentions as applied for aeronautical structural materials because its high strength, high stress corrosion cracking resistance and good fatigue resistance when treated by retrogression and re-aging(RRA). Al-8Zn-2Mg-2Cu(mass fraction,%) thick plate is supposed to manufacture the aircraft wing in Chinese big plane project. Due to the non-isothermal environment in the process of heat treatment for aluminum alloy thick plate, the influence of coupling effect of non-isothermal retrogression temperature field and time on the microstructure and properties of Al-8Zn-2Mg-2Cu alloy thick plate was investigated by the non-isothermal kinetic model, mechanical properties tests, electrical conductivity test and TEM observations. The results show that, the electrical conductivity increases while the hardness and strength decrease with the non-isothermal retrogression time increasing. The optimized non-isothermal retrogression and re-aging (NRRA) treatment makes the size distribution range of MgZn2 phase wider. The logical matching between the dislocation cutting off mechanism and the dislocation bypassing mechanism improves the electrical conductivity significantly with a little strength sacrifice. After the treatment of 105 ℃, 24 h (pre-aging) and non-isothermal regression (120 min) with slow heating rate and 120 ℃, 24 h re-aging, the Al-8Zn-2Mg-2Cu alloy thick plate possesses an excellent comprehensive performance than those of T6 and T73 state. The tensile strength, yield strength and electrical conductivity are 620 MPa, 593 MPa and 21.1 MS/m, respectively. The NRRA treatment with slow heating rate is more suitable for the aging treatment of thick plate. 全文下載：https://pan.baidu.com/s/1sl5Gnr3
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