Determination of Annealing Process of Cold Rolling Steel Sheets of Hot Dip Galvanized Steel Sheets

The cold rolling hard steel sheets of SS Grade40,SS Grade33 and SS Grade50 hot dip galvanized steel sheet were annealed by salt-bath annealing method with different process. The effect of annealing process on the microstructure and mechanical properties of these three kinds of cold rolling steel sheets was studied,and the recrystallization temperature and optimum annealing temperature range for them were determined. The results show that the recrystallization temperature of SS Grade40 cold rolling steel sheet was approximately 720 ℃ and the optimum annealing temperature for it was also 720 ℃. The recrystallization temperature of SS Grade33 cold rolling steel sheet was approximately 680 ℃,and considering the stability of mechanical properties,the optimum annealing temperature for it was determined to be approximately 720 ℃. The recrystallization temperature of SS Grade50 cold rolling steel sheet was above 700 ℃,and in order to ensure the margin of strength and the stability of properties,the optimum annealing temperature was determined to be approximately 780 ℃.