A personal computer based system to evaluate J-integral by a single specimen unloading compliance method—part II: Results on A533B class I steel and corona-5

Abstract

A PC-based single specimen unloading technique was described in Part I of the paper. In this paper the applicability of the technique is demonstrated using two different materials: a nuclear grade pressure vessel material, A533B Class I steel and an α- β titanium alloy, CORONA-5. Experimental parameters investigated in the case of steel include the effect of test temperature, loading rate and neutron irradiation. Results revealed the effect of dynamic strain aging (DSA) as a drop in the critical crack initiation fracture toughness ( J q ); the minimum in J q shifts to higher temperatures at higher test speeds as predicted from DSA models. In CORONA-5, the effects of microstructure and heat treatment for two different sizes of equiaxed α morphology in a β-matrix heat treated to different yield strengths were investigated. It is found that the observed higher values of J q and tearing modulus result from a greater tortuosity of the crack path and ease of crack blunting. The largest increase in J q occurred in fine equiaxed α microstructure aged to a nominal yield strength of 896 MPa. Results reveal potential application of the low cost technique for determining fracture toughness of engineering materials.