Small punch test method assessment for the determination of the residual creep life of service exposed components: outcomes from an interlaboratory exercise

Abstract

The main aim of the experimental work described is the comparison of the results of the conventional creep tests with those of small punch creep tests, i.e. of miniaturized disc bending tests performed on 14 MoV 6 3 and X20 CrMoV 12 1 steels, respectively, in different laboratories. It turned out that, in the case of small punch tests, too, the time to fracture can be calculated using an equation of the Dorn type, in which load is substituted for stress. However, the creep activation energies calculated according to this equation are somewhat lower than those relating to the conventional uniaxial creep tests. A comparison of the results of the tests carried out in different laboratories showed that the repeatability of small punch tests carried out within an individual test laboratory or using the same item of testing equipment is very good and perfectly comparable with the repeatability of results using conventional creep tests.