热处理制度对GH706合金显微组织与拉伸性能的影响

Effect of Heat Treatment on the Microstructure and Tensile Properties of Superalloy GH706

采用金相显微镜和扫描电镜研究轧态GH706合金经标准热处理和直接时效热处理后的显微组织,测量合金的室温拉伸性能后,结果表明:直接时效热处理使合金晶粒组织显著细化,标准热处理合金晶界析出尺寸较大的短棒状、颗粒状或针状η相,直接时效热处理合金晶界η相以细小颗粒状析出;合金的室温屈服强度、抗拉强度、延伸率和断面收缩率分别提高了9.5%、7.5%、16.3%和45.5%。分析相关结果发现:直接时效热处理通过增加晶界面积,阻碍位错运动和协调晶粒间变形;同时,晶界细小颗粒状η相可以提高合金晶界强度,因而显著提升合金的室温拉伸性能。

The microstructure of as-rolled superalloy GH706 after standard heat treatment and direct aging treatment was studied by metallographic microscope and scanning electron microscope.The tensile properties of the alloy were measured at room temperature.The results showed that direct aging heat treatment produced finer grain size of the alloy.Short rod-like,granular or needle-likeηphases were observed at grain boundaries of the standard heat-treated alloy,while small granularηphases precipitated as fine particles in the alloy subjected to direct aging heat treatment.The yield strength,tensile strength,elongation and area reduction of the alloy at room temperature in the experiment increased by 9.5%,7.5%,16.3%and 45.5%respectively.The improvement in tensile properties for the direct aging alloy was attributed to its smaller grain size,which increased the grain boundary area and thus hindered dislocation movement and coordinated the deformation between the grains.In addition,theηphases presented as small granular at grain boundaries could improve the grain boundary strength of the alloy.