退火温度对GH3600合金箔材组织与性能的影响

目的 探究退火温度对GH3600镍基高温合金箔材微观组织及力学性能的影响。为制备综合性能良好的GH3600箔材提供参考。方法 将厚度为2 mm的铸态板材反复轧制退火得到组织均匀的0.3 mm厚度带材，再利用四辊冷轧机将带材轧制成厚度为0.1 mm和0.05 mm的箔材，然后将2种厚度箔材在950、1 000、1 050 ℃下保温1 h后空冷。通过金相观察、电子探针、EBSD检测及XRD分析来研究箔材的微观组织演变。通过拉伸实验检测箔材的室温拉伸性能。结果 随着变形程度的增大，轧制态箔材晶粒沿轧制方向被拉长得更加明显。在相同热处理参数下，0.05 mm退火态箔材晶粒尺寸更小。退火后，箔材晶粒发生了回复再结晶并析出了细小的碳化物。随着退火温度的升高，晶内碳化物逐渐减少，孪晶界比例增大，再结晶程度及晶粒尺寸增大。0.05 mm箔材在1 050 ℃退火时，其晶粒迅速粗化，在厚度方向上出现单层晶，导致箔材的抗拉强度及延伸率出现异常降低的现象，即“越小越弱”的尺寸效应。结论 适宜的热处理工艺有助于改善箔材的微观组织，进而提高其力学性能。0.05 mm箔材在950 ℃下退火1 h时，其延伸率为19.1%，屈服强度以及抗拉强度分别达到293 MPa和560 MPa，综合力学性能良好。

Effect of Annealing Temperature on Microstructure and Properties of GH3600 Alloy Foil

The work aims to explore the effects of annealing temperature on the microstructure and mechanical properties of GH3600 nickel-base superalloy foil and provide reference for preparing GH3600 foil with good comprehensive properties. The 2 mm thick cast sheet was repeatedly rolled and annealed to obtain uniform 0.3 mm strip, and then the strip was rolled to foils of 0.1 and 0.05 mm by a four-roll cold rolling mill. The foils of the two thicknesses were kept at 950, 1 000 and 1 050 ℃ for 1 h and then air-cooled. The microstructure evolution of the foils was studied by metallographic observation, electron probe, EBSD detection and XRD analysis. The mechanical properties of foils were measured by tensile test. With the increase of deformation degree, the grain elongation of rolled foils along the rolling direction became more obvious, and a large number of shear bands appeared. After annealing, the foil grains recrystallized and small carbides precipitated. With the increase of temperature, the carbide decreased gradually, the proportion of twin boundary increased, and the degree of recrystallization and grain size increased. Under the same heat treatment parameters, the grain size of 0.05 mm annealed foil was smaller than that of 0.1 mm recrystallized foil. When 0.05 mm foil was annealed at 1 050 ℃, the grain was coarsened rapidly, and a single layer crystal appeared in the thickness direction, resulting in an abnormal decrease in the tensile strength and elongation of the foil with the thinning of the thickness and the increase of the temperature, namely the "smaller and weaker" size effect. The appropriate heat treatment process is helpful to improve the microstructure of the foil and improve its mechanical properties. The elongation of 0.05 mm foil annealed at 950 ℃/1 h is 19.1%, and the yield strength and tensile strength reach 293 MPa and 560 MPa, respectively. The mechanical properties are good.