Life Extension of Creep Damaged Low Alloy Steel Welds by Regenerative Heat Treatment

Weldments in high-energy piping of fossil power plants are known to suffer extensive creep damage over the course of long-term operations. This damage appears in the form of macro cracks, which result from the formation and linkage of creep cavities at the grain boundaries. It has been reported that creep cavities become sintered when subjected to compressive stress at high temperatures, and, if they could be eliminated before they develop into macro cracks, it was considered that this would enable life extension of components. This paper presents a process of regenerative heat treatment for the life extension of low alloy steel weldments by means in localized high-temperature heating of deteriorated locations. It is shown that recovery of creep life is attained as a result of high temperature compression tests and heat cycles around the A3 transformation temperature.