1992 Volume 78 Issue 6 Pages 918-925
Creep curves of 1.3Mn-0.5Mo-0.5Ni steel were analyzed using the modified θ projection concept based on the following equation:
ε=ε0+A{1-exp(-αt)}+B{exp(αt)-1}
where ε is the strain, t is the time, and ε0, A, B and α are the parameters determined by curve fitting. The equation could describe the measured creep curves over the whole creep stages up to 90 percent of the rupture life. The modified θ projection concept could successfully predict long term rupture lives obtained independently on the same material.
Heat-to-heat variations in creep properties were discussed on the basis of the creep curve analysis. The parameters ε0, A and α were invariable among all the heats investigated. Only the parameter B related to the weakening process was different among the heats, indicating that the difference in the weakening parameter B was primarily responsible for the heat-to-heat variations.
