Research on Redissolution Behavior of Nb and Ti in the High Strength Pipeline Steel

In this study,the redissolution and precipitation behaviors of niobium titanium carbonitride（Nb,Ti）（C,N） were researched by electrolytic phase analysis method and calculated by the simplified thermodynamic calculation method,and the dissolution law of Nb and Ti elements in high Nb pipeline steel was studied.The results showed that when the reheating temperature ranged at 1 180～1 280 ℃,the actual redissolution amount of Nb and Ti were lower than those of calculated values.When the reheating temperature was lower than 1 250 ℃,increasing temperature and heating time resulted into the significant solution amount of Nb in steel.When reheated at 1 250 ℃ for about 2.5 h,nearly 90% of niobium comes into solution and 11% of titanium into solution,since the titanium carbonitrides formed by have good stability.