Effect of galvannealing parameters on coating properties of DP590 steel plate

Abstract

To analyze the effect of galvannealing (GA) parameters on the alloying behavior of DP590 dual phase steel plate, SEM, surface roughness measuring instrument were applied to investigate the surface morphology, cross-sectional structure and surface roughness of the galvannealed coatings under different GA processes. The results show that with GA temperature rising and GA time prolonging, the content of ζ phase decreases and the content of δ phase increases, and small holes appear on the surface of the coating. When GA temperature is 480℃, surface roughness of the galvannealed coating on DP590 steel plate increases with the prolonging of time. While GA temperature is 500℃ and 520℃, the surface roughness decreases with time extension. When GA time is 25 s, the surface roughness decreases with the rising of temperature. While GA time is 20 s, with the rising of GA temperature, the surface roughness decreases first and then increases. With GA temperature rising and GA time extending, alloying degree deepens, and Γ phase appears in the galvannealed coating when GA temperature is 520℃ and GA time is 25 s.