SYMPOSIA PAPER Published: 01 January 1956

Relaxation Properties of Steels and Super-Strength Alloys at Elevated Temperatures


Tabulated data and graphical presentations summarize relaxation strengths for low-alloyed Mo-, Cr-, and V- bearing steels with numerous other composition modifications, 12 per cent Cr type steels with many compositional variations, a number of super-strength alloys, and cast iron. Residual stresses for relaxation to 100, 500, 1000 and 10,0000 hr are the main measure of relaxation strength. A lesser amount of data for the 10-hr relaxation strengths are given in some cases. The temperatures covered mainly range from 750 to 1100 F with data at 1200 to 1500 F for super-strength alloys. One set of data shows relaxation of high-strength carbon-steel wires at room temperature. The tabulated data also include chemical composition, heat treatment, mechanical properties at room temperatures, and limited creep data. The relaxation strengths are shown graphically to indicate the ranges of values for the individual alloys. In this form, the range in strength for a given alloy was frequently rather wide. This was found to be mainly due to variations in initial stress, heat treatment and major alloying elements. When sufficient data were available, graphical correlations were included to define the effect of these variables. It was very evident that direct comparison of relaxation strengths of different alloys could only be made on the basis of nearly similar initial stress. Curves of relaxation strength versus temperature on a reasonably comparative basis were developed in so far as possible for a single initial stress at each temperature. These initial stresses were arbitrarily based on those stresses for which most data were available. The comparative curves are also based on data for most usual conditions of heat treatment for each alloy. It is important to clearly understand that the level of relaxation strength indicated by the comparative curves would be different for any other initial stress in a majority of the materials tested and are therefore in no sense average strengths.

Author Information

Freeman, James, W.
University of Michigan, Ann Arbor, Mich.
Voorhees, Howard, R.
University of Michigan, Ann Arbor, Mich.
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Developed by Committee: E01
Pages: 1–6
DOI: 10.1520/STP47588S
ISBN-EB: 978-0-8031-6979-1
ISBN-13: 978-0-8031-6543-4