精密铸件反重力铸造凝固组织与缺陷控制研究进展

Research Progress on Solidification Microstructure and Defect Control in Counter Gravity Casting of Precision Castings

镍基高温合金、钛合金和铝镁合金等精密铸件是航空航天重大装备中重要的热端部件,目前,更高的使用温度、更大的构效比和更高的机动性等航空航天装备建设的需求,促使精密铸件向大型化、复杂化和薄壁化方向发展。反重力铸造技术具有充型稳定、压力可控等优点,是生产优质精密铸件的理想方法。早在20世纪70年代,国外就能够利用反重力精密铸造技术制造大型精密铸件。近年来,我国一些高校和研究院所也相继在反重力铸造方面开展了大量研究,在铝镁轻合金方面积累了大量经验,也具备了小批量生产能力。目前,国内的产品技术水平与国外还有一定的差距,特别是在高温合金反重力铸造方面,国内还处于起步阶段。在精密铸造过程中,疏松、裂纹、变形和尺寸超差等各类铸造缺陷的形成严重影响了铸件的使用性能,降低了铸造产品的合格率。基于此,结合反重力铸造工艺原理及技术特点,概述了反重力铸造技术的应用现状,详细综述了精密铸件反重力铸造过程中组织、缺陷的形成规律和重要的铸造缺陷预测模型,并对反重力铸造技术的发展趋势进行展望。

Nickel-based superalloy,titanium alloy,aluminum-magnesium alloy and other precision castings are important hot end components in aerospace major equipment.At present,higher use temperature,larger structure-efficiency ratio,higher mobility and other aerospace equipment construction needs promote the development of precision castings towards large-scale,complex and thin-walled direction.Counter gravity casting technology is an ideal method for producing high-quality precision castings due to its advantages of stable filling and controllable pressure.As early as in the 1970s,foreign countries were able to use counter gravity precision casting technology to manufacture large-scale precision castings.In recent years,some universities and research institutes in China have also carried out a lot of research in counter gravity casting,accumulated a lot of experience in aluminum-magnesium light alloy,and also obtained the ability of small scale production.However,there is still a certain gap in product technology level between China and foreign countries,especially in the counter gravity casting of superalloy,which is still in the initial stage.The formation of various casting defects such as looseness,cracks,deformation and dimensional out-of-tolerance in the precision casting process seriously affects the performance of castings and reduces the qualification rate of casting products.Based on this,combined with the counter gravity casting process principle and technical characteristics,the work aims to review the application status of counter gravity casting technology,summarize the formation law of microstructure and defects in the process of counter gravity casting of precision castings and important casting defect prediction models in detail and prospect the development trend of counter gravity casting technology.