effect of microstructure on hydrogen embrittlement of weld simulated HSLA-80 and HSLA-100 steels.pdf

I. INTRODUCTION LOW-CARBON, copper-precipitation-strengthened HSLA steels have emerged as suitable replacements for the conventional high-carbon quenched and tempered HY steels for the naval ship hull structure. The HY series of steels are vulnerable to weld cracking because of the formation of untempered martensite due to the combined action of high- carbon content and alloying elements. The possible means to obviate this difficulty is to follow stringent welding process control by preheating and postweld soaking treatments or with the reduction in carbon content to a level too low to form untempered martensite. The HSLA steels meet the property requirements at a significantly lower fabrication cost due to the elimination of preheating and postweld soaking treat- ments. However, as the ship hull is cathodically protected to prevent corrosion from seawater, usually by using sacrificial anode zinc, cathodic hydrogen makes its way into the mater- ial causing embrittlement. At the developmental stage of HSLA steels, Montemarano et al.[1] have certified that the fracture toughness and tearing modulus of HSLA-80 steel are comparable and in some cases much better than those of HY steels. The fracture toughness data from precracked cantilever beam stress corrosion cracking (SCC) tests at a zinc level of cathodic protection indicated immunity of this steel to SCC for both the base material and the weldment. A similar behav- ior for HSLA-100 steel has been reported by Czyryca et al.[2] Weld strength is a dominating factor in assessing the over- all performance of the materials for ship hull construction. This has been shown in the work of Zanis et al.[3] while Effect of Microstructure on Hydrogen Embrittlement of Weld-Simulated HSLA-80 and HSLA-100 Steels K. BANERJEE and U.K. CHATTERJEE HSLA-80 and HSLA-100 steels have been subjected to weld-simulated grain-coarsened heat-affected zone (GCHAZ) and grain-refined heat-affected zone (GRHAZ) treatments at peak temperatures of