The effects of V, Nb and Ti on the creep property and the toughness of weld metals for high Cr ferritic heat resisting steels were investigated. The following were clarified:
(1) Increasing V from 0mass% to 0.11mass% improves the creep property and impairs the toughness. Increasing V by more than 0.11mass% impairs the creep property and improves the toughness.
(2) The creep property is improved and the toughness is impaired by adding a small amount of Ti.
(3) Addition of Nb improves the creep property and impairs the toughness. However it improves the balance between the creep property and toughness more than the addition of V and Ti.
(4) The changes of the properties due to V, Nb and Ti could be explained by changes in the morphology of MX.
(5) The changes in morphology of MX could be explained by changes of driving force and grain growth kinetics.
