Investigation of Hydrogen Assisted Crack in Welding by using Y-Groove Test

Abstract

Ferritic steel with Cr and Mo as major alloying elements are used extensively in nuclear power plants, fossil power plants, and petrochemical industries where the material is exposed to temperatures in the range of 550C to 630C. These steels are widely used because of their high strength, good creep resistance, and low coefficient of thermal expansion. These steels have martensitic or bainitic structure in the normalized condition and hence are susceptible for hydrogen assisted cracking (HAC) during welding. Modified 9Cr-1Mo steel, grade 91 has been selected for steam generator of Proto type Fast Breeder Reactor (PFBER). During fabrication of steam generator component, welding is unavoidable. Indigenous design of PFBR and fabrication of components is under way. Along with development of different materials for PFBR, modified 9Cr-1Mo steel electrodes were also developed indigenously to meet the PFBR specification of impact energy of minimum 45 J at ambient temperature from Charpy V-notch impact testing. In the present study the susceptibility of the weld joint made by these electrodes to HAC has been evaluated using widely used Y-groove test.