吹砂、抛光及其电解腐蚀后处理对单晶高温合金表面组织和再结晶行为的影响

Effects of Grit Blasting,Polishing and Their Electro-etched Post-treatment on Surface Microstructures and Recrystallization Behavior of Single Crystal Superalloy

采用吹砂处理、砂带抛光、毡轮抛光3种表面处理使铸态单晶(SX)Ni基高温合金叶片表面形成塑性变形层,对叶片表面变形层进行电解腐蚀实验,然后进行标准热处理,研究了单晶高温合金叶片表面处理的变形层及其电解腐蚀后显微组织。结果表明:3种表面处理的铸态单晶高温合金叶片表面变形层深度分别约为6,3.5μm和2μm,并在吹砂处理和砂带抛光的表面变形层周围存在显微裂纹;表面变形层电解腐蚀过渡区内存在大量γ′变形组织,且3种表面处理的塑性变形残存量依次递减,而变形层完全电解腐蚀区内无塑性变形痕迹;标准热处理后,变形层未电解腐蚀区存在凹陷特征和再结晶晶粒,但无塑性变形痕迹;变形层完全电解腐蚀区无明显凹坑和再结晶晶粒。

Plastic deformed layers of as-cast single crystal （SX） nickel-based superalloy blade surface were formed by using three kinds of surface treatment process （grit blasting, abrasive belt polishing, felt wheel polishing）. The deformed layers were electrolytic etched by using a specially designed electrolytic device, followed by standard heat treatment. Surface-treated deformed layers of single crystal superalloy blade and its electro-etched microstructures were investigated. The results show that the depths of deformed layers on as-cast SX blade surface are respectively about 6, 3. 5μm and 2μm by using three kinds of surface treatment process. The microcrack fracture characteristics exist around the surface deformed layers by grit blasting and abrasive belt polishing. Large amounts of deformed 7＇ structure is existed in the electro-etched transition region of surface deformed layers, and the residual plastic deformation of three kinds of surface treatment process decreases successively in electro-etched transition region. Plastic deformation is not found in totally electro-etched region. After standard heat treatment, sag characteristics and recrystallized grains exist in non electro-etched region of deformed layers, but neither obvious pits nor recrystallized grains are found in totally electro-etched region.