Tensile properties, fracture toughness and crack growth study of alloy C-276

The results of tensile testing involving austenitic Alloy C-276 indicated that this material is capable of maintaining adequate structural strength at temperatures relevant to the H2SO4 decomposition process related to the nuclear hydrogen generation. This alloy exhibited a unique phenomenon known as dynamic strain aging, which has been studied as a function of both temperature and strain rate. An average value of 55 KJ/mole has been determined to be the activation energy for plastic deformation under tensile loading at different temperatures. Increased crack extension was observed in wedge-loaded double-cantilever-beam specimens exposed to an acidic solution and subjected to higher initial stress intensity factor values. The self-loaded specimens did not exhibit cracking in the same environment. Ductile failures were observed at temperatures up to 600°C. However, intergranular brittle failures were observed at higher temperatures.