Interpretation of creep crack growth data for ½ CMV steel weldments

Abstract½Cr½ Mo¼ V (½ CMV) steel has been used in high temperature power plant piping due to its enhanced weld properties. Creep crack growth testing has been performed on compact tension C(T) specimens of ½CMV (low alloy ferritic) steel at 540◦C on both parent metal specimens as well as fine and coarse grained heat affected zone (HAZ) specimens, where the initial crack is located within the HAZ. The data has been interpreted using the fracture mechanics parameter C* against the crack growth rate. The creep toughness parameter, Kcmat, is also evaluated for the material. It was seen that, for a given C* value, the fine grained HAZ material generally exhibits higher crack growth rates than the post weld heat treated coarse grained HAZ