喷射成形工艺的理论研究进展

Theoretical models in spray forming

喷射成形是人为地控制凝固条件,经过金属熔体的分散、飞行快速冷却、半固态凝固及锭坯进一步冷却等阶段,得到特殊的锭坯组织的成形过程。沉积锭坯组织是上述四个阶段金属熔体凝固的综合结果。近终形成形是喷射成形技术的另一特点,喷嘴形式、喷嘴数量、沉积器的形状与运动方式影响和决定沉积锭坯的外形。材料的凝固与成形受众多因素影响,很多工艺参数的作用规律尚不明确,因此喷射成形过程的模拟研究十分必要。笔者介绍了目前喷射成形工艺中所涉及的理论问题与相关模型。

Spray forming involves sequential stages of the melt atomization, the droplet quenching, the droplet consolidation on collision and the preform cooling in continued processing step. These sequential stages control and change the solidification conditions of the melt and determine the spray formed preform＇s microstructure. Near-netshape manufacturing is another characteristic of the spray forming. The preform＇ s shape depends on the structure and amount of jet, the shape and movement of the substrate. Material microstructure and shape of the spray formed preforms are influenced by many factors. However, the effects of the processing parameters have not been made clear yet. So it is still necessary to study the spray forming process by experimental and numerical simulation. Theoretical models applied to spray forming were discussed in this paper.