AbstractTwo recently developed mechanical tests–a stress versus strain rate relaxation test and a constant displacement rate notched bar test–are described as a basis for measuring the effect of prior creep exposure on 2·25Cr–1Mo steel. These tests were used to monitor property changes resulting from prior creep, in both laboratory tests and also following service exposure in T-pieces of fossil plant main steam piping. Significant changes of properties were measured. These post-exposure tests may be used to monitor damage evolution during service and could form the basis of a life management methodology.MST/1501