An Investigation of Multi-Axial Creep Characteristics of Metals

Abstract

Conventionally, uniaxial creep test data provide the designer of engineering components at elevated temperature with an assessment of the creep behavior of the metal with which he is concerned. However for more rigorous design, methods are required whereby uniaxial creep data may be used to provide predictions of the behavior of those components for multi-axial stress conditions. This paper describes research, mainly at the author’s laboratory, into multi-axial creep relationships revealed by studies on a spectrum of engineering metals and the use of these relationships in the derivation of creep design methods for engineering components from tensile creep data. Finally the paper reports an application of recently developed reference stress methods to the prediction of the time-dependent behavior of a representative engineering component under a complex stressing history. Indications of the likely success of the reference stress technique as a tool for initial design assessment and its limitations are shown.