Effects of microstructure on the high temperature constitutive behavior of IN100

Document Type

Conference Proceeding

Publication Date

2004

Department

Department of Materials Science and Engineering

Abstract

An experimental program was conducted in order to determine the effects of microstructure on the high temperature constitutive behavior or powder-processed IN 100. The relevant application is the high pressure turbine disk in a gas turbine engine. Eight different microstructures were prepared, with 260°C yield strengths ranging from 945 to 1165 MPa. For each microstructure, tensile tests and cyclic constitutive tests were conducted at 260°C and 650°C. This paper reports on the tensile test results. The tensile curves were fit to a modified Ramberg-Osgood constitutive model, which contains four material constants. It was found that two of the constants were sensitive to microstructure, while two others were not. The constant K 1 which is analogous to the strength coefficient in the traditional power-law hardening expression, varied in exactly the same way as the yield strength. The variations in yield strength and K1 were consistent with the Huther-Reppich strength model, with the secondary γ′ size being the dominant microstructural term. There was also a smaller effect of tertiary γ′and grain size. The hardening exponent n, which is basically the inverse of the hardening exponent in the traditional power-law hardening expression, was sensitive to secondary γ′ size and also to the presence of primary γ′, but not to grain size.

Publication Title

Proceedings of the International Symposium on Superalloys

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