作　　者： ; ; ;

机构地区： 东北大学材料与治金学院材料各向异性与织构工程教育部重点实验室

出　　处： 《中国材料进展》 2011年第5期15-20,33,共7页

摘　　要： 以国产蒸汽发生器传热管用GH690合金为研究对象，通过评价其断裂韧性及拉伸特性，结合光学显微镜、扫描电镜和透射电镜分析，研究了合金由室温～623K的力学性能。研究结果表明，室温下GH690合金低的层错能，易生成形变孪晶，使得合金在孪生的协调下塑性变形能力提高，同时孪晶促进裂纹扩展转向，使合金在断裂过程中吸收更多的能量，维持合金高的断裂韧性。随着温度的升高，合金的层错能增加，导致形变孪晶生成困难，合金应力集中程度加剧，裂纹从而平直扩展，合金的断裂韧性降低。由于合金的室温层错能较低，合金在拉伸时能够通过孪生协调变形，同时生成的孪晶阻碍了位错的滑移而提高了合金的强度和塑性。随着形变温度的升高，合金通过孪生协调变形的能力降低，导至合金的变形机制由孪生转变为滑移，滑移产生的加工硬化效应小于孪生，故合金的强度和延伸率随之降低。 GH690 alloy made in China was employed as the testing material in the present research. The mechanical behaviors of GH690 alloy were investigated with both fracture toughness testing and tensile testing from RT to 623 K, combined with the analysis of optical microscopy （OM） , scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. The results indicate that the lower stacking fault energy of GH690 alloy at room temperature easily leads forming of deforming twins, thus resulting in higher plastic deformation ability of the alloy with the twinning coordination. At the same time, crack turning caused by twinning makes the alloy absorb more energy and keep high fracture toughness. With the increasing of testing temperature, the stacking fault energy increases, which makes it hard to form deforming twins, and the degree of stress concentration increases and crack propagates straightly, therefore the fracture toughness decreases.

关 键 词： 合金 温度 断裂韧性 拉伸变形

领　　域： [金属学及工艺] [金属学及工艺]