6082铝合金热轧带材表面鼓包原因及对策

Reasons and countermeasures for surface bubble of 6082 aluminum alloy hot-rolled strip

我公司生产6082铝合金热轧带材时部分产品表面出现了类似气泡的小鼓包缺陷,最初按气泡缺陷攻关,强化熔铸精炼和除气,然而收效甚微;进一步研究发现,这不是一个简单的铸锭氢含量高引起的热轧带材表面鼓包,而是铸锭内部有未溶解的大尺寸Si颗粒导致的,是原辅材料Al-Si中间合金质量异常,内部有大量未溶解的、表面已氧化的Si颗粒残留造成的.质量异常的Al-Si中间合金与夹渣类似,热轧剧烈变形时,在表面氧化的残留Si颗粒位置发生应力集中出现微裂纹,富集的氢在微裂纹处膨胀,将带材表面顶起,最终在带材表面形成类似于气泡的鼓包缺陷.鉴于此,熔铸换用了优质Al-Si中间合金,新生产的铸锭热轧带材没有再出现这种类似气泡的小鼓包缺陷,实现了产品稳定供货.

Small bubble-like defects appeared on the surface of some products of 6082 aluminum alloy hot-rolled strip produced by our company.We initially focused on the bubble defects and strengthened the melting and refining and degassing,but the effect was very tiny.Further research found that this was not a simple bulge on the surface of hot-rolled strip caused by high hydrogen content in the ingot,but caused by undissolved large size Si particles inside the ingot.It was caused by the abnormal quality of the raw and auxiliary material Al-Si master alloy and a large number of undissolved and oxidized Si particles inside.The Al-Si master alloy with abnormal quality is similar to the slag inclusion.When the hot rolling causes severe deformation,microcracks appear at the stress concentration at the position where there are surface oxided residual Si particles,and the enriched hydrogen expands at the microcracks,which will lift the thin shell,and finally form bubble-like bulging defects on the surface of the strip.In view of this,high-quality Al-Si master alloy was used for melting and casting,and the newly produced ingot hot-rolled strip did not have this kind of bubble-like small bulge defect again,realizing consistent product supply.