"The codes covering fabrication of virtually all steel structures and pressure vessels require that weldmetal strength equal or exceed base-metal strength. Until recently@ however@ it was rare that consideration would be given to how much weld-metal strength in excess of basemetal strength was acceptable. There are certain instances@ such as when machining of the weld is to be done@ or when the weld is to see service in a corrosive environment@ that an overly strong or hard weld causes problems. The particular situation of hard welds in corrosive service has caused concern in the petroleum-refining industry and has provided the motivation for the study to be described herein@ which was sponsored by the American Petroleum Institute's Division of Refining@ Subcommittee on Corrosion@ under the direction of the Task Group on Corrosion Research. A number of failures have occurred recently in plain carbon-steel (70 ksi ultimate tensile strength or less) vessels containing among other substances@ water and hydrogen sulfide@ as might occur near the end of a petroleumrefining operation. Frequently@ failure has consisted of transverse weld cracking in submerged-arc welds. The cracked welds are usually substantially harder than the base metal. Some instances of weld heat-affected-zone cracking are also known to occur. The cracking mechanism is variously referred to as ""sulfide-corrosion cracking"" ""hydrogen-stress cracking@"" ""stress-corrosion cracking@"" ""wet sulfide cracking@"" and the like. A combination of high-strength metal@ stress and a source of nascent hydrogen (usually a corrosion reaction) seems to be required to produce the cracking."
BULLETIN 184-1973 history
1973BULLETIN 184-1973 SUBMERGED-ARC WELD HARDNESS AND CRACKING IN WET SULFIDE SERVICE