C2024-20899 Effect Of Heat Treatment And Manufacturing Method On The Susceptibility To Hydrogen Induced Stress Cracking Of UNS N06625

Roy Johnsen, Eivind Thorstensen, Atle Qvale, Vebjørn Andresen, Paal Bratland - HSC resistance was examined by use of hydrogen pre-charging and stepwise loading of tensile specimens in a hydrogen charging environment. The testing was followed by fractography characterization and microstructural examination by use of Optical Light Microscope (OLM) and Scanning Electron Microscope (SEM).The hot forged and the HIP’ed versions that subsequently were heat treated, were found to be susceptible to HSC. Among the hot forged and heat-treated versions, the samples heat treated at 1010°C were found to be the most susceptible, while heat treatment at 1100°C resulted in the lowest susceptibility. The solution annealed (1150 °C) and cold worked version showed a higher resistance, as no reduction in fracture strength, nor any secondary cracking were observed.The amount of grain boundary precipitations was found to be the main factor influencing the HISC susceptibility, where an increased amount