新型熔炼工艺下GH4169合金的凝固组织控制研究

Microstructure control of GH4169 alloy during a new melting and solidification process

为探求新型熔炼工艺(三联)下GH4169合金大型重熔锭组织调控、元素偏析改善的方法,研究了熔速对氩气保护电渣重熔GH4169合金重熔锭枝晶间距、Laves相的尺寸及分布和显微疏松的影响,定量分析了熔速对组织与成分偏析的影响规律.研究发现:随着熔速的增加,GH4169合金重熔锭边缘处的枝晶间距基本保持不变;中心处二次枝晶间距呈增大趋势.边缘和中心处的疏松尺寸随熔速增加变化平缓,R/2处先增大后减小.心部的Laves相比例较高且随着熔速增加呈上升趋势,而R/2处趋势相反;重熔锭不同部位的偏析区比例随熔速无明显变化.枝晶间距越小,越有利于减轻偏析.

In order to reduce micro-segregation in large volume GH4169 ingot produced by electroslag remelting process and improve its quality by optimizing the microstructure,the influence of various melting rate on the dendrite arm spacing,size and distribution of Laves phase and micropores in different regions of the ingot were investigated. It was found that the dendrite arm spacing close to the edge of the remelting ingot almost remained the same despite the increase of the melting rate,while the secondary dendrite arm spacing became larger in the central part. Melting rate had weak impact on the dimension of micropores near the edge and center,however the dimension of micropores at R / 2 increased first and then decreased thereafter. In the center part,the Laves phase precipitates were more populated and the concentration increased with the melting rate,whereas it showed an opposite trend in the R / 2 region. The element segregation showed no significant changes in different area. The results also indicated that smaller dendrite arm spacing led to weaker microsegregation.