Abstract：Due to the selective oxidation of Si and Mn during the annealing process of Si-Mn added high strength steel which significantly deteriorates the wettability of strip with liquid zinc,the galvanizability of hot dip galvanized high strength steel is still a challenge. To improve the coating adhesion of hot dip galvanized high strength steel,characterizations of the inhibition layer on coating/substrate interface and the internal oxidation in the subsurface of hot dip galvanized 0.2%C-1.8%Si-1.8%Mn high strength steel sheets with different coating adhesion were conducted by GD-OES,SEM,FIB and TEM. Annealing simulation experiments were used to study the effect of annealing atmosphere dew point on the formation of internal oxidation. The correlation between dew point,internal oxidation thickness,inhibition layer coverage and coating adhesion was revealed. The coating adhesion is determined by the inhibition layer on the coating/substrate interface,good coating adhesion can be obtained when the coverage of inhibition layer is greater than 80%. There exists a critical internal oxidation thickness which is approximately 0.58 μm. When the internal oxidation thickness gradually increases from 0 to 0.58 μm,the inhibition layer coverage increases from 10% to 80% approximately. When it further increases from 0.58 μm to 3.85 μm,the inhibition layer coverage increases slightly in the range of 80%-90%. The internal oxidation is promoted when the dew point of the annealing atmosphere is increased. When it is annealed at 800 ℃ and 870 ℃ and soaked 120 s in an atmosphere of N2-5% (volume percent)H2,the internal oxidation thickness increases from 0 to 3-5 μm as the dew point increases from -40 ℃ to +10 ℃. Therefore,it is suggested to control the dew point of annealing atmosphere in the range of -20 ℃ to -10 ℃ to get a favorable internal oxidation thickness.
储双杰, 金鑫焱, 毕文珍. 内氧化对热镀锌高强钢镀层/基板界面的影响[J]. 钢铁, 2021, 56(12): 126-133.
CHU Shuang-jie, JIN Xin-yan, BI Wen-zhen. Influence of internal oxidation on coating/substrate interface of hot dip galvanized high strength steel sheet[J]. Iron and Steel, 2021, 56(12): 126-133.
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2021, Vol. 56 
