Oxidation behavior and mechanical properties of Inconel 617

Abstract

Inconel 617 is commonly used as a heat exchange tube and hot gas ducting material for high temperature gas-cooled reactors (HTGRs). In the present study, the oxidation behavior and mechanical p ropc πi es of Incone1 61 7 ‘,\`ere studied after exposure to high temperature (1050 t ) in air and He environments. Oxidc layers were analyzed by SEM and EDS The dominant oxide layer was Cr-ox idc. An intemal oxide and Cr-depleted zone wasobserved below the Cr-ox ide layer The thickness of theinternal oxide and Cr-dcplcted zone representedthe degrcc of oxidation. The degree of oxidation increased with exposure ti me. In the air environment, thc intcmal oxide layer and Cr-depleted zone 、，vere thicker than those in the He environmenl because of higher oxygen partial pressure. Thc grain size of thc specimen increased with exposure time. The prec ipitated phases in the matrices region were identified. The major phases were M23C6 and M6C-type carbides. The composition of M23C6 and M6C were determined by EDS to be Cr-rich and Mo-rich carbides, respectively. Measuring the hardness of thc Inconel 617 in different environments was carried out by a Rockwell hardness tester