CREEP AND FRACTURE FEATURE OF SUPERALLOYS WITH DIFFERENT BOUNDARY MICROSTRUCTURES IN SULPHUR CONTAMINATED ENVIRONMENT
ZHANG Yuanhu;XIANG Yi;SUN Jian;HU Gengxiang;LI Tiefan Shanghai Jiaotong University Institute of Metallic Corrosion and protection Academia Sinica; Shenyang
Cite this article:
ZHANG Yuanhu;XIANG Yi;SUN Jian;HU Gengxiang;LI Tiefan Shanghai Jiaotong University Institute of Metallic Corrosion and protection Academia Sinica; Shenyang. CREEP AND FRACTURE FEATURE OF SUPERALLOYS WITH DIFFERENT BOUNDARY MICROSTRUCTURES IN SULPHUR CONTAMINATED ENVIRONMENT. Acta Metall Sin, 1990, 26(5): 44-49.
Abstract Studies by SEM and EDAX were carried out on the high temperaturecreep and fracture behaviour undergone tests in air or in SO_2 contaminated enviro-nment for both Fe-base wrought superalloy GH302 and Ni-base superalloy Rene 80,with two different microstructures: i. e., flat and zig-zag grain boundary or equi-exed and Columnar grain boundary respectively. Although the creep rupture strenqthof the superalloy GH302 of zig-zag GB was remarkably superior to that of flat GBin air, the properties of both dropped suddenly in 10% SO_2 contaminated air. Thecreep rupture properties of the directional solidification superalloy Rene 80 weremuch better than that of the conventionally casted alloy in air, and also remainedthe former ones in SO_2 contaminated air. Owing to the interaction between creepand sulphidation, the damage mechanism seems to be that the creep cracking ispropagated intergranularly by suffering sulphidation-oxidation corrosion under stress,and formation of a low melting point NiN_3S_2 eutectic leads to premature failure ofthe alloy.
