Nearly all creep data are obtained under closely controlled constant conditions of load and temperature. Most high-temperature plant, however, is subject to cyclic variations of both, due to periodic off load or reduced load conditions.
Test data for a C-Mn steel are presented for various cycles of stress and/or temperature. The effects of cycling of stress or temperature, and of in-phase changes of both, are predictable within reasonable limits. It is shown, however, that with out-of-phase changes in stress and temperature, i.e. high stress/low temperature to low stress/high temperature conditions, a very rapid acceleration of strain can occur.
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References
1.
MansonS. S.‘Creep under non-steady temperatures and stresses’, Mechanical behaviour of materials at elevated. temperatures1961, edited by DornJ. E. (McGraw-Hill, London).
2.
‘Symposium on effect of cyclic heating, and stressing on metals at elevated temperatures’, ASTM Special Technical Publication No. 165, 1954.
3.
WilsonD. V.‘Creep under non-constant stress or temperature’, RAE Library Bibliography No. 24, 1962.
4.
KennedyA. J.Processes of creep and fatigue in metals1962 (Oliver and Boyd, Edinburgh).
5.
AveryH. S.‘Cyclic temperature acceleration of strain in heat resisting alloys’, Trans. Am. Soc. mech. Engrs193860, 253.
6.
ToftL. H.BroomT.‘Exploratory tests on the effects of temperature and load cycling on creep resistance and microstructure of two austenitic steels’, Joint Int. Conf. Creep, Proc. Instn mech. Engrs1963–64178 (Pt 3A), 3–77.
7.
MargraveD.WilloughbyG.‘Effect of temperature cycling and aging on the creep properties of Esshete 1250 bar and steam pipe’, J. Iron Steel Inst.1965203 (4), 286.
8.
TairaS.OhnamiM.SakatoM.‘Influence of temperature history on creep’, Bull. J.S.M.E.19625 (17), 1.
9.
GuarnieriG. J.‘The creep rupture properties of aircraft sheet alloys, subjected to intermittent load and temperature’, ASTM Special Technical Publication No. 165, 1954.
10.
BenhamP. P.‘Low endurance fatigue’, Thermal stress (based on Symposium at Imperial College, London) 1964, edited by BenhamP. P.HoyleR. (Pitman, London).
11.
WatsonS. J.‘Creep and stress relaxation with thermal cycling’, Thermal stress (based on Symposium at Imperial College, London)1964, edited by BenhamP. P.HoyleR. (Pitman, London).
12.
BrophyG. R.FurmanD. E.‘Cyclic temperature acceleration of strain in heat resisting alloys’, Trans. Am. Soc. Metals194230 (4), 1115.
13.
DayM. F.CummingsW. M.MillsG. H.‘Effect of stress relief on creep resistance of carbon-manganese steel’, Brit. Welding J.196512 (11), 531.
14.
MillerJ.‘Effect of temperature cycling on the rupture strength of some high temperature alloys’, ASTM Special Technical Publication No. 165, 1954, 53.
15.
GuarnieriG. J.YerkovichL. A.‘The influence of periodic overstressing on the creep properties of heat resistant alloys’, Proc. Am. Soc. Test. Mater.195252, 934.
16.
MontandonR.KirchnerF.‘The effect of varying temperature and stress on creep strength’, Brown Boveri Rev.196350 (11/12), 767; also Engrs Dig. 1964 25 (5), 98.
17.
BerkovitsA.‘Investigation of three analytical hypotheses for determining material creep behaviour under varied loads’, N.A.S.A. Technical Note D-799, 1961.
