EFFECT OF WELD THERMAL CYCLE ON PARTICLES IN Ti-Nb-V MICROALLOYED STEEL

By using carbon extraction replica technology, the response of particle in Ti-Nb-V microalloyed X-60 Steel to Weld Thermal Cycle is investigated. Experiment results and analysis show that the particles in the steel change from irregular shape to cubicle one after thermal cycle. t sub 8/5 has a great effect on the chemical composition, mean size and number per unit area of the particles after weld thermal cycle. When t sub 8/5 change from 10 s to 45 s, all particles remain rich in Ti, the mean size increases and the number per unit area decreases, indicating that no re-precipitation occurs. When t sub 8/5 changes from 45 s to 120 s, particles rich in Nb + V appear, the mean size decreases and the number per unit area increases, indicating that re- precipitation occurs in case of large t sub 8/5 .