Effect of precipitates on the creep rupture behavior of GH4141 superalloy
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摘要: 研究了析出相与GH4141合金蠕变持久断裂行为的交互作用，涉及蠕变裂纹萌生和扩展。表征手段采用二次电子和电子背散射衍射技术，重点关注了析出相（包括MC、M6C、M23C6型碳化物和γ′弥散强化相）、孔隙和晶界裂纹，同时分析了晶粒塑性变形和强化机制。孔隙主要发生在晶界与M6C和M23C6碳化物的界面处，相邻孔隙聚合形成涟漪形貌，裂纹生长加剧了其前端区域的塑性变形。晶粒内部强化涉及γ′析出相对位错运动的抑制，由于应变激活多个滑移系统，加快了位错塞积和缠结现象，起到强化晶粒的效果。Abstract: This study focused on the effect of precipitates on the creep rupture behavior of GH4141 superalloy, involving creep crack initiation and propagation. Microstructures including carbides, γ′ precipitate hardening phase, void and intergranular crack were characterized by SE and EBSD. Meanwhile, plastic deformation and hardening mechanisms for crystal grains were analyzed. Voids occurred at the interfaces of grain boundary and carbides. Voids coalescence with wavy morphology were observed. The increase in crack length enhanced plastic deformation degree in front of the crack tip. The crystal grain strengthening was caused by the suppression of dislocation motion resulting from γ′ pinning effect. Due to the activation of multiple glide systems, dislocation piled up and tangled to enable crystal grain strengthening.
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Key words:
- GH4141 superalloy /
- creep rupture /
- precipitate /
- crack propagation /
- precipitates hardening
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图 1 背散射成像下的GH4141合金微观组织
（a）蠕变持久试验前；（b）蠕变持久试验39 h 后
Figure 1. BSE images of microstructures in GH4141
图 2 蠕变持久39 h 后断口形貌及局部放大
（a）断口全局形貌；(b)剪切滑移导致的穿晶断裂形貌；（c）不同方向的滑移带；（d）沿晶断裂形貌（图中标记1～3所示）和穿晶断裂形貌（图中标记4和5）；（e）伴有滑移带和密集韧窝的穿晶断裂面；（f）嵌入在韧窝（黄色曲线区域）内部的MC型碳化物
Figure 2. Fracture morphology and local magnified images after 39 h creep tests
图 4 (a) 沿晶微裂纹及其周边碳化物；（b）不同视角下的微裂纹及其（c）断裂面局部放大
Figure 4. (a) Intergranular small cracks and the surrounding carbides, (b) the same crack observation in different view and (c) the magnified image of fracture surface
图 5 塑性应变区域二次电子图像及其EBSD数据
（a）孔隙聚合导致的涟漪形貌局部放大；（b）碳化物附近形成孔隙聚合现象；（c）碳化物关联的裂纹；图（a）对应的EBSD数据以不同形式呈现：（d）菊池带衬度图；（e）KAM图；（f）取向图
Figure 5. Secondary electron images of the plastic strain region and the corresponding EBSD data
表 1 GH4141合金化学成分
Table 1. Chemical composition of GH4141 superalloy
% C Cr Al Ti Co Mo B Mn Si S Fe Ni 0.06～0.12 18～20 1.4～1.8 3～3.5 10～12 9～10.5 0.003～0.01 <0.1 <0.5 <0.015 <5.0 Bal. 
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