Investigation of Fracture Mechanism Before and After Thermal Cycling Stellite12 Cobalt-based Alloy with Tensile Tests
ZHANG Haiyan1, CAO Rui1, CHE Hongyan2, LIU Guohui2, CHEN Jianhong1
1 State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metal, Lanzhou University of Technology, Lanzhou 730050; 2 Advanced Technology ＆ Materials Co., Ltd., Beijing 100086
Abstract: By means of in-situ tensile tests of Stellite12 cobalt-based alloy (after the thermal cycling shock at 700 ℃ / 20 ℃ for different times and unshocked) with different notch size, in combination with the analysis of experiment data and SEM observation of fracture, the tensile fracture process and fracture mechanism were investigated before and after thermal cycling shock of Stellite12 cobalt-based alloy. The result of in-situ tensile experiment reveals that after the thermal cycling, the fracture process of specimen with different size notch has a little difference. There were micro surface cracks on the root of small circular notch specimen and many oxydic micropores on the specimen edge and side of the cracks after thermal cycling. When the sample experienced in-situ tensile test, cracks extended in the direction of the thickness of the specimen firstly on the process of thermal shock, to be connected in thickness direction, and then the substrate phase of the crack tip deformation occurred, black phase (white phase) transgranular cracking, oxydic micropores expanding, specimen instantaneously fracturing in the end. But the great circle specimen after thermal cycling shock generated no obvious crack on the surface. During in-situ tensile test, the substrate phase of the crack tip deformation occurred, with black phase (white phase) transgranular cracking, oxydic micropores expanding, specimen instantaneously fracturing. While, the original unshocked specimen experienced deformation, transgranular cracking and fracture when energy accumulating. Three kinds of original specimens are similar to the process of fracture because the stress concentration of the small arc radius specimen is bigger, so as to make its fracture stress lower than the tablet and the great circle sample.
张海燕,曹 睿,车洪艳,刘国辉,陈剑虹. Stellite12钴基合金热循环冲击前后拉伸断裂机理研究[J]. 《材料导报》期刊社, 2017, 31(24): 156-160.
ZHANG Haiyan, CAO Rui, CHE Hongyan, LIU Guohui, CHEN Jianhong. Investigation of Fracture Mechanism Before and After Thermal Cycling Stellite12 Cobalt-based Alloy with Tensile Tests. Materials Reports, 2017, 31(24): 156-160.
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2017, Vol. 31 
