Creep under Complex Stress Systems at Elevated Temperatures

Abstract

During the last few years a programme of creep tests under general stress systems at elevated temperatures has been carried out at the National Physical Laboratory (N.P.L.), using four metallic alloys (a cast 0.17 per cent carbon steel, an aluminium alloy—RR. 59, a magnesium alloy containing 2 per cent aluminium, and a nickel-chromium alloy—Nimonic 75) chosen as representative of basic groups of materials used in practice, and tested at temperatures lying within their normal working range. In this paper an effort is made at a general comparison of the complex stress creep characteristics of the materials, and such generalizations as appeared possible. Appendices are provided, dealing respectively with: experimental data for one of the materials (data for the others having been published elsewhere); the effect of hydrostatic stress on complex stress creep, and specific examples of application of the data.