铝合金空心锭内孔拉裂漏铝原因及防止措施

Causes for the cracking and aluminum leakage of aluminum alloy hollow ingot bore and corresponding preventive measures

为了解决热顶铸造铝合金空心铸锭生产中产生的内孔拉裂及漏铝问题,对漏铝部位纵向切片检查,发现漏铝前通常会出现拉痕和拉裂,但也发现没有出现拉裂现象的突发性漏铝特例。查阅相关文献,结合生产实际分析了空心锭内孔产生拉痕、拉裂及突发性漏铝的原因。基于铸造机制,从铸造工具、铸造参数和操作工艺等方面提出了防止内孔拉裂、漏铝的措施,成功研制了加装排气装置的铝合金空心锭热顶铸造结晶器。研制的热顶铸造结晶器可有效降低铸管内气体压力,解决了铸井溢流排水情况下频发漏铝问题。在满足使用性能的前提下,提高合金强度、降低材料应力、提高材料塑性等降低裂纹敏感性的措施均可避免热顶铸造空心锭内孔裂纹、拉裂缺陷的产生。

The longitudinal section examination was carried out on the position of cracking and leakage to solve the problem of cracking and aluminum leakage in hot-top casting of aluminum alloy hollow ingot bore. It is found that stretching mark and drawing cracking usually occur before aluminum leakage, but there is also sudden aluminum leakage without cracking. On the basis of production practice and literature research, the main causes for stretching mark, drawing cracking and sudden aluminum leakage in hollow ingot bore were analyzed. Based on the casting mechanism, the measures to prevent bore cracking and aluminum leakage were proposed from the aspects of casting tools, casting parameters and operation technology. A hot top casting mold for aluminum alloy hollow ingot with exhaust device was successfully developed, which can effectively reduce the gas pressure in the casting pipe and solve the problem of frequent aluminum leakage caused by overflow and drainage of the casting well. On the premise of meeting the service performance, the measures to reduce the crack sensitivity, such as increasing the alloy strength, reducing the material stress, and improving the material plasticity, can avoid the occurrence of bore cracking and drawing cracking in hot top casting hollow ingot.