Weldadility of Fe-36%Ni Alloy (Report V) : Behaviors of Grain-boundary Sliding and Cavity Formation Preceding Reheat Hot Cracking in Weld Metal(Materials, Metallurgy & Weldability)

To reveal the mechanism of reheat hot cracking in weld metal of Invar, microstructural behaviors concerning the cracking, namely grain-boundary sliding, cavity formation, grain-boundary migration and recrystallization during hot ductility test were studied. Main conclusions obtained are as follows: (1) Grain-boundary sliding and its resultant cavity formation are prerequisite to the cracking. (2) One of the reason for high ductility in the temperature below the temperature region giving ductility trough causing the crack is the difficulty of grain-boundary sliding. (3) Grain-boundary migration and dynamic recrystallization have important roles in raising the ductility in the high temperature region of the ductility trough.