Abstract: Continuous annealing tests were conducted on tinplate with different nitrogen contents at different temperatures (595-710 ℃) using a continuous annealing testing machine. The microstructure, grain size, hardness, and tensile properties of the annealed tinplate were analyzed. The results show that the increase in nitrogen content raises the recrystallization temperature of the tinplate, while also refines grain size and inhabits grain growth. The hardness and strength of tinplate with higher nitrogen content are both higher than those with lower nitrogen content. The main nitrogen precipitates are dispersed rectangular TiN and AlN, which increase with the increase of nitrogen content. When the annealing temperature is raised to above 690 ℃, the lamellar pearlite in tinplate with different nitrogen contents is distributed along grain boundaries, replacing the granular pearlite distributed along the rolling direction. Based on the experimental results, controlling the continuous annealing temperature for the production of high-hardness tinplate in the industrial production within the range of 645-660 ℃ can reduce the hardness fluctuation and improve the canning efficiency.

Key words: tinplate, nitrogen content, continuous annealing, precipitate, microstructure, properties