The Affect of Martensite Laryer at Weld Bond On the Fracture Toughness of 9%Ni Steel Joints Welded by Austenitic Electrodes OK69.45

Optical microsope observarion and TEMA was used to study the microstructures at weld bond and HAZ of the 9%Ni steel joints welde by austenitic electrode-OK69.45.Special specimens were designed to measure the fracture toughness in the two regions during COD test,and the fractographic experiment was also made by SEM.The results shown that the structures in the martensite layer at weld bond is lath martensite,there is no significant difference in the COD valie between weld bond and over heated zone.The existence of martensite laryer does not reduce fractuer toughness value of the joints.