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采用末端淬火实验、光学显微镜、扫描电子显微镜、透射电子显微镜和差示扫描量热法,研究了时效制度对7055铝合金厚板淬透性的影响.结果表明:人工时效前进行长时间的自然时效可提高板材的淬透性,自然时效和人工时效的淬透深度分别约为78和45 mm,而自然+人工时效的淬透层深度可达100 mm.冷却速率减小时,析出了粗大的η平衡相,溶质和空位浓度降低,时效后的η′沉淀强化相数量减少,尺寸增加,因此硬度降低.人工时效前的长时间自然时效有利于慢速冷却处形成稳定的GP区,最终得到数量更多、分布更均匀弥散、尺寸更细小的η′沉淀强化相,硬度升高,提高了淬透性.
The effect of aging system on the hardenability of 7055 aluminum alloy plate was studied by means of end quench test, optical microscope, scanning electron microscopy, transmission electron microscopy and differential scanning calorimetry.The results showed that: Aging can improve the hardenability of the sheet, natural aging and artificial aging hardened depth of about 78 and 45 mm, respectively, and the natural + artificial aging depth of hardened layer up to 100 mm cooling rate decreases, the precipitation of coarse η equilibrium phase, the concentration of solute and vacancy decreases, the number of precipitated η ’precipitates decreases and the size increases after aging, thus reducing the hardness.The long time natural aging before artificial aging is conducive to the formation of a stable GP zone at slow cooling, and finally More number, more evenly distributed dispersion, size smaller η ’precipitation strengthening phase, the hardness increased, increased hardenability.