Hydrogen embrittlement of ESR processed 12Cr-1Mo steel

Tensile tests were performed to determine the effect of hydrogen on the ductility of a quenched-and-tempered 12Cr-1Mo alloy from the National Fusion Heat-ESR processed. Specimens were cathodically charged with hydrogen at 0.003 A/cm2 and 0.006 A/cm2 for 15 to 150 minutes. In the uncharged condition, the ESR specimens failed by intergranular rupture with prominent secondary cracking along prior austenite grain boundaries. For the least severe cathodic charge (0.003 A/cm2 - 15 minutes), the tensile ductility (R/sub A/) decreased 33% and the degree of secondary cracking increased. At 0.003 A/cm2 for 150 minutes, the ductility decreased further and the fracture mode changed to classical intergranular fracture. Auger analysis indicates that there is segregation of phosphorous and the carbide-forming elements Cr, Mo, W to the prior austenite grain boundaries