Principal metallurgist, The Welding Institute, Cambridge,
Pages: 71 Published: Jan 1990
Weldments in structural and pipeline steels have been characterized in terms of hardness and microstructure (using light and electron microscopy) and resistance to stress corrosion cracking (SCC) in NACE TM-01-77 test solution. In addition, the propensities of the steels for pitting and hydrogen pickup in NACE solution have been determined, and stress corrosion fracture surfaces have been examined in the scanning electron microscope.
The principal factor affecting susceptibility to SCC was hardness, after which the presence of martensite was the only factor that clearly increased risk of cracking. While there were marked differences in hydrogen pickup and pitting tendency, no direct correlation with risk of cracking was observed.
It is concluded that the use of hardness limits is applicable to carbon-manganese steel weldments operating in sour environments, but that compositional ranges over which such limits are used need to be determined. Attention is also drawn to the fact that the inter/sub critical heat affected zone (HAZ) could be the most susceptible region for cracking in some steels.
fatigue (materials), environmental effects, carbon-manganese steels, welded joints, structural steels, pieplines, microalloyed steels, hardness, microstructure, electron microscopes, metallography, stress corrosion, cracking, pitting corrosion, fractography, martensite, hydrogen, heat affected zone
Paper ID: STP24068S