____________ is a form of environmental cracking that can initiate on the surface of high strength low alloy steels and carbon steels with highly localized zones of high hardness in the weld metal and HAZ as a result of exposure to aqueous HF acid service.
Hydrogen stress cracking is a form of environmental cracking that can occur in high strength low alloy steels and carbon steels with highly localized zones of high hardness in the weld metal and heat-affected zone (HAZ) as a result of exposure to aqueous hydrofluoric acid (HF) environments. This type of cracking is characterized by the introduction of hydrogen into the steel, which leads to embrittlement and subsequent cracking under tensile stress.
Hydrogen stress cracking is a form of environmental cracking that can occur in high-strength low-alloy (HSLA) steels and carbon steels with highly localized zones of high hardness in the weld metal and HAZ, as the result of exposure to aqueous HF acid environments.
Carbon steels and low-alloy steels are of prime concern, particularly older steels. 400 series SS are also susceptible even if not embrittled. In addition, materials susceptible to an embrittling mechanism such as sigma phase embrittlement (3.56), 885 °F (475 °C) embrittlement (3.1), temper embrittlement (3.63), strain-aging embrittlement (3.60), or titanium hydriding (3.66) pose a risk for brittle fracture if they are sufficiently embrittled.