针对湿法冶金过程中传统线性搅拌工艺导致的多相介质混合不均,混合过程能耗高等问题,提出了变速机械搅拌耦合蒸汽喷吹强化混合工艺,增加了搅拌釜内部的混沌流区域,打破原有的混合隔离区,从而提高搅拌反应釜内部的整体混合效率。通过数...针对湿法冶金过程中传统线性搅拌工艺导致的多相介质混合不均,混合过程能耗高等问题,提出了变速机械搅拌耦合蒸汽喷吹强化混合工艺,增加了搅拌釜内部的混沌流区域,打破原有的混合隔离区,从而提高搅拌反应釜内部的整体混合效率。通过数值模拟的方法,构建volume of fraction(VOF)多相流模型和Lee蒸汽冷凝相变模型,对多相混合过程进行量化。结果表明,变速机械搅拌耦合蒸汽喷吹条件下搅拌流场合速度提高了38.04%,湍动能强度提升了40.01%。展开更多
The superplastic forming of Ti alloy welds has great application prospects in producing integrated components. However, the nugget zone（NZ） of the Ti alloy welds,produced by fusion welding or conventional friction s...The superplastic forming of Ti alloy welds has great application prospects in producing integrated components. However, the nugget zone（NZ） of the Ti alloy welds,produced by fusion welding or conventional friction stir welding（FSW）, consists of lamellar micro structure, which exhibits either low superplasticity or high superplastic temperautre and low strain rate. As a result, the NZ plays a leading role in hindering the superplastic forming of the whole welds.In this study, submerged friction stir welding（SFSW） was conducted in Ti-6Al-4 V alloy for the first time, and a defectfree weld with the NZ consisting of a strip microstructure was obtained. The NZ exhibited a low-temperature superplasticity at 600℃, which was the lowest superplastic temperature ever reported in the Ti alloy welds. Besides, at 800℃, the NZ showed high strain rate（3×10^（-2） s^（-1）） superplasticity and a largest elongation of 615% at 1×10^（-3） s^（-1）. Compared to conventional FSW joints, the NZ of SFSW joint exhibited a much lower flow stress and a decrease in optimal superplastic temperature by 100℃. This is mainly attributed to the easy globularization of the strip microstructure, enhancing the ability of grain/phase boundary sliding.展开更多
文摘针对湿法冶金过程中传统线性搅拌工艺导致的多相介质混合不均,混合过程能耗高等问题,提出了变速机械搅拌耦合蒸汽喷吹强化混合工艺,增加了搅拌釜内部的混沌流区域,打破原有的混合隔离区,从而提高搅拌反应釜内部的整体混合效率。通过数值模拟的方法,构建volume of fraction(VOF)多相流模型和Lee蒸汽冷凝相变模型,对多相混合过程进行量化。结果表明,变速机械搅拌耦合蒸汽喷吹条件下搅拌流场合速度提高了38.04%,湍动能强度提升了40.01%。
基金supported by the National Natural Science Foundation of China under Grant(51471171,51601194,and 51331008)
文摘The superplastic forming of Ti alloy welds has great application prospects in producing integrated components. However, the nugget zone（NZ） of the Ti alloy welds,produced by fusion welding or conventional friction stir welding（FSW）, consists of lamellar micro structure, which exhibits either low superplasticity or high superplastic temperautre and low strain rate. As a result, the NZ plays a leading role in hindering the superplastic forming of the whole welds.In this study, submerged friction stir welding（SFSW） was conducted in Ti-6Al-4 V alloy for the first time, and a defectfree weld with the NZ consisting of a strip microstructure was obtained. The NZ exhibited a low-temperature superplasticity at 600℃, which was the lowest superplastic temperature ever reported in the Ti alloy welds. Besides, at 800℃, the NZ showed high strain rate（3×10^（-2） s^（-1）） superplasticity and a largest elongation of 615% at 1×10^（-3） s^（-1）. Compared to conventional FSW joints, the NZ of SFSW joint exhibited a much lower flow stress and a decrease in optimal superplastic temperature by 100℃. This is mainly attributed to the easy globularization of the strip microstructure, enhancing the ability of grain/phase boundary sliding.
