Tensile Deformation of Alloy-22 at Ambient and Elevated Temperatures

Significant efforts are in progress to identify and characterize the tensile properties of structural materials for application in hydrogen generation using a thermochemical process known as the sulfur-iodine cycle. Austenitic Alloy-22 has been evaluated for its tensile properties at temperatures ranging from ambient to 1000°C. As expected, the tensile strength was gradually decreased with increasing temperature due to the ease of plastic deformation at these temperatures. However, the failure strain gradually decreased from room temperature to 600°C, possibly due to the occurrence of a phenomenon known as dynamic strain aging. Transmission electron microscopy revealed maximum dislocation density at 600°C. Fractographic evaluation of the tested specimens by scanning electron microscopy showed dimpled microstructures at the primary fracture surface indicating ductile failures. However, at higher temperatures intergranular brittle failures were observed