STUDY OF CREEP EMBRITTLEMENT OF 2-1/4Cr-1Mo STEEL WELD METAL.

A study of creep embrittlement in 2-1/4 Cr-1 Mo steel weld metal has shown that heat treatment prior to creep has a greater effect on ductility than on rupture or creep strength. If the creep temperature is high enough to cause tempering, the rupture resistance and creep strength will be characteristic of the creep temperature. Prior heat treatment only affects weld metal strength when the temperature of creep is significantly below that of the prior heat treatment so that tempering does not occur during creep. The mechanism of creep embrittlement is shown to be related to the generation of intergranular voids. This is controlled by the formation of a denuded zone and the segregation of residual elements to the intergranular precipitate/matrix interfaces.