High-Temperature Intergranular Crack Growth in Martensitic 2-1/4 Cr-1Mo Steel

Micromechanisms of high-temperature crack growth in martensitic 2 1/4 Cr-1Mo steel have been studied in vacuum, under static loading at 500 C. Detailed metallographic and fractographic measurements have been combined with Scanning Auger Microscopy and crack growth resistance curves to characterize the micro-mechanisms of failure. At low Stress intensities, the mode of crack growth is high-temperature, brittle intergranular fracture (HTBIGF) and is controlled by the dynamic segregation of sulphur to crack-tip regions. Crack advance appears to occur by discrete jumps when a critical concentration of sulphur is achieved over the jump distance. Keyword: Great Britain.