AA8011铝合金高通量连铸连轧铸嘴堵塞的原因

Cause of nozzle clogging of HTCR AA8011 aluminum alloy

采用OM、SEM、EDS、XRD和辉光放电质谱仪研究了HTCR(高通量连铸连轧)AA8011铝合金铸嘴堵塞的机制。结果表明,经过净化处理后,AA8011铝合金熔体中固体非金属夹杂物含量不是造成铸嘴挂渣堵塞的主要原因。随着铸造时间的增加,铝合金熔体中接触到铸嘴表面的液态杂质随温度的降低析出凝固,造成铸嘴表面粗糙度增加,引起铸嘴挂渣。在高温下铝熔体长时间与铸嘴材料中的SiO_2颗粒接触,在铸嘴表面形成Al_2O_3颗粒,加剧了铸嘴堵塞的发生。熔融铝液在铸嘴凹凸不平的表面容易凝固,铸嘴型腔内逐渐变得狭窄,最终导致铸嘴堵塞。在堵塞的铸嘴型腔内形成三层结构分布—反应层、挂渣层与金属层。

The nozzle clogging mechanism of HTCR （high throughput casting and rolling） AA8011 aluminum alloy was investigated by OM, SEM, EDS, XRD and GDMS. The results show that clogging is not mainly caused by the content of solid nonmetallic inclusions in the melt of AAS011 aluminum alloy after purification. As casting time goes on, the liquid impurities in aluminum alloy melt contacting with the low-temperature surface of the nozzle will precipitate andsolidify, thus increasing the roughness of the nozzle＇s surface and causing the nozzle slag. A1203 is formed at the nozzle＇s surface when SiO2 particles of the nozzle material react with the melting aluminum after long time contact under high temperature, as a result significantly increasing the nozzle clogging. The aluminum liquid is prone to solidify on the protruding surface of the casting nozzle. The solidification narrows the nozzle cavity and leads to nozzle clogging. Reactive layer, slag layer and metal layer are then formed in the clogging nozzle cavity.