Measurements of creep at high temperatures using helical springs

Abstract

A method is described of calculating the extension of a loaded helical spring due to creep in the material. Measurements are reported on the extension of springs of stainless steel En 58 J with different loads at 650°C up to stress levels of 3000 lb/in2. It is shown that the creep extension is dominated by a primary creep mechanism up to at least 500 h and estimates are obtained for the primary creep parameters. The time exponent is shown to be 0.3 and the stress exponent 0.87.