GH350合金铸锭元素偏析及其均匀化热处理

Microsegregation and Homogenizing Treatment of GH350 Ingot

利用光学显微镜、扫描显微镜及能谱仪,研究了经双联真空(VIM+VAR)冶炼生产的130mm自耗锭GH350合金铸态和不同均匀化过程中显微组织和元素偏析的规律。结果表明,铸态GH350合金中存在复杂的第二相组织和严重的枝晶偏析,Nb、Ti、Ta等溶质元素大量偏聚于枝晶间的Laves相等第二相中,而Cr、Mo等元素则偏聚于枝晶干。并且发现铸态GH350合金经1 180℃×40h炉冷后,枝晶偏析基本消除,合金成分基本均匀。

The as casting microstructure and homogenization of the GH350 alloy ingot was investigated by means of optical microscopy,scanning electron microscopy（SEM） and EDX analysis.The precipitation of as-cast GH350 alloy is complicated and the dendritic segregation is severe.Nb,Ti and Ta are segregated to the interdendritic region and enriched in the precipitates such as Laves phase,while Cr and Mo are segregated to the dendrites.It is found that the dendritic segregation between the dendrites within the casting grains of the GH350 alloy ingot can be basically eliminated by annealing at 1 180 ℃×40 h.