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研究了添加不同含量的稀土元素对Al-Mg-Si汽车板材的时效特性及微观组织的影响。研究表明,提高时效温度可使合金达到硬度峰值的时间缩短,但硬度值较低。稀土可以细化晶界析出物,改善第二相的分布和形状,减小第二相沉淀质点的几何尺寸,增大粒子的分布密度且分布较均匀,加速了合金的时效过程,使得合金达到峰值时效的时间变短,硬度值有所提高。预时效可以形成细密、均匀、弥散的G.P.区,使得在随后的时效过程中形成高密度的强化相,减少自然时效的不利影响,提高合金的硬度。含有稀土的合金预时效后硬度提高约28%,加入稀土后较为适宜的预时效工艺为140℃10 min。
The effects of adding different amounts of rare earth elements on the aging characteristics and microstructure of Al-Mg-Si automotive sheet were studied. Studies have shown that increasing the aging temperature can make the alloy shorten the time to reach the peak hardness, but the hardness value is low. Rare earths can refine grain boundary precipitates, improve the distribution and shape of the second phase, reduce the geometric size of the precipitated particles in the second phase, increase the distribution density of the particles and distribute them more evenly, accelerate the aging process of the alloy, Peak aging time shorter, the hardness value has increased. Pre-aging can form a fine, uniform, dispersed G.P. zone, resulting in the subsequent aging process to form a high-density reinforcing phase, reducing the adverse effects of natural aging and increasing the hardness of the alloy. The hardness of the rare earth-containing alloys increases about 28% after pre-aging, and the more suitable pre-aging process after adding rare earth is 140 ° C for 10 min.