将超声场引入7050铝合金半连续铸造过程中，用Leica光学显微镜观察了铸锭的组织，结合RDG热裂纹判据和凝固补缩理论分析了超声场对热裂纹形成的影响机理。结果表明：在未施加超声场的铸锭中心发现有热裂纹，而施加超声场的铸锭中没有发现热裂纹；施加超声场的铸锭组织均匀，晶粒显著细化，组织由未加超声场时的柱状晶变为等轴晶；施加超声场可有效抑制热裂纹的形成。
Ultrasonic field was applied to prepare 7050 aluminum alloy semi-casting aluminum alloy ingot, the microstructure of the ingots were observed by Leica optical microscopy and the effect mechanism of ultrasonic field on hot tearing forming was analysed by combining the RDG hot tearing criterion and solidification shrinkage theory. The result show that a crack was found in the center of the ingot without ultrasonic field and no crack was found in the ingot with ultrasonic field. The microstructure of ingot with ultrasonic field was homogeneous, the grain size was obviously refined and the microstructure was changed into equiaxed grains from dendritic crystals without ultrasonic field. The ultrasonic field could effectively depress hot tear forming.
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