Creep Properties Assessment of P92 Steel by Small Punch Creep Tests

Abstract

Small punch creep (SPC) tests have the potential as an alternative to conventional uniaxial creep tests when limited amount of material is available. This paper investigates the applicability of SPC to evaluate the creep deformation behavior of P92 steel. SPC results have been compared with uniaxial creep test results in order to establish the correlation between the two tests. Small punch tests on P92 steel have been performed at 600 °C in the load range of 1000–400 N. The load dependence of minimum deflection rate was found to obey Norton’s power law but with a two slope behavior exhibiting distinct values of load exponents in the low and high load regimes. Transition in fracture mode of SPC specimens from ductile transgranular at high loads to brittle intergranular fracture at low loads was in accordance with the large variation in load exponent values. Monkman–Grant equation interrelating minimum deflection rate with rupture time has been found to be valid for SPC data. Correlations between SPC load and minimum deflection rate with uniaxial creep stress and minimum creep rate respectively, established based on empirical relations suggest the relevance of SPC for evaluating creep properties in relatively short time.