Abstract: Through the study of continuous annealing process of hot dip galvanized structural steel strip S550GD+Z without adding precious metal, the influence of different annealing soaking temperatures and holding time on the microstructure and properties was studied. The results show that when the annealing soaking temperature is 605 ℃ and the holding time is 105-132 s, the yield strength and tensile strength of the specimen can reach or being more than 570 MPa and 600 MPa respectively, and the elongation can reach or being more than 10%, which can meet the standard requirements for mechanical properties of the S550GD+Z steel strip.

Key words: hot dip galvanized S550GD+Z steel strip, annealing soaking temperature, holding time, mechanical properties