Performance of weldments in advanced 9%Cr steel–‘FB2’

AbstractThe improvement of tensile and creep rupture strength, achieved by the development of martensitic-ferritic 9–12%Cr creep-resistant steels, known as creep strength enhanced ferritic (CSEF) steels, is attractive to designers who want to take advantage of them to improve power plant efficiency and reduce component wall thickness. However, although parent alloy developments have been making good progress, weldment performance has been of increasing concern. In particular, the cross-weld creep performance for CSEF steels is an issue, with Type IV cracking characterised by rupture in the outer region of the heat affected zone (HAZ) and low strain to failure being the typical features of failure in cross-weld tests. In this investigation, narrow gap TIG welding, flux-cored arc welding (FCAW) and reduced pressure electron beam (RPEB) welding were employed to produce a series of butt welds in a new European steel–FB2–a wrought, boron-containing 9%Cr steel. These welds were subjected to metallurgical examin...