GH4169合金在冷轧和热处理过程中的组织演变和力学性能

Microstructure Evolution and Mechanical Properties of GH4169 Alloy During Cold Rolling and Heat Treatment

摘要:

采用扫描电子显微镜、电子背散射衍射和透射电子显微镜研究了GH4169合金在冷轧和热处理过程中的组织演变和力学特征。结果表明，随着冷轧变形的增加，晶粒被拉长成纤维状，微观组织中未观察到δ相。热处理后，原始变形晶粒被细小的再结晶晶粒取代，晶粒尺寸随着冷轧变形量的增加和热处理温度的降低而减小。但当变形量大于50%时，出现混合晶粒结构。热处理温度为950和990 ℃时，基体中存在δ相析出。随变形量的增加，δ相含量而增加，形态由短棒状变为球状。在冷轧状态下，当变形量为70%时，抗拉伸强度（UTS）达到1484.27 MPa，是冷轧态合金（772.5 MPa）的1.92倍，但延伸率（EL）降低到8.93%。然而经过990 ℃热处理后，延伸率提高到46.47%，是冷轧状态合金EL的5.2倍。冷轧变形量为50%、热处理温度为990 ℃时，获得了最佳的力学性能组合（UTS=943.59 MPa，EL=52.31%）。

Abstract:

The microstructure evolution and mechanical properties of GH4169 alloy during cold rolling and heat treatment were investigated by scanning electron microscope, electron backscatter diffraction, and transmission electron microscope. Results show that the grains are elongated into fibers with increasing the cold rolling deformation degree, and no δ phase can be observed in the microstructure. After heat treatment, the original deformed grains are replaced by small recrystallized grains, and the grain size is decreased with increasing the cold rolling deformation degree and decreasing the heat temperature. However, the mixed grain structure appears after cold rolling deformation of 50%. When the heat treatment temperature is 950 and 990 °C, the δ phase is precipitated in the matrix. The content of δ phase is increased with increasing the deformation degree and the morphology is changed from short rods into spherical shapes. When the deformation degree is 70%, the ultimate tensile strength (UTS) reaches 1484.27 MPa, which is 1.92 times higher than that of the cold rolled alloy (772.5 MPa). However, the elongation (EL) decreases to 8.93%, and it increases to 46.47% after heat treatment at 990 °C, which is 5.2 times higher than that of the cold-rolled alloy. The optimal combination of mechanical properties (UTS=943.59 MPa, EL=52.31%) can be achieved when the cold rolling deformation degree is 50% and the heat treatment temperature is 990 °C.