PURPOSE: To improve the heat resistance and high-temp. strength of an Al plated steel sheet obtd. in the stage of producing said steel sheet by incorporating a specific amt. of Ti and Nb into the steel sheet and coiling the steel sheet within a specific temp. range in a continuous hot rolling stage.
CONSTITUTION: A steel having the compsn. contg. 0.005W0.020% C, 0.05W0.40% Mn, <0.010% N, 0.10W0.50% Ti where the ratio of Ti/(C+N) is made to ≥10, 0.05W0.30% Nb and 0.01W0.10% Al is used for a steel sheet in the stage of producing an Al plated steel sheet by subjecting a cold rolled steel sheet to Al hot dipping. The coiling in the continuous hot rolling stage for the steel sheet is accomplished in a temp. range of 550W650°C. The (Ti, Nb) carbonitride is uniformly and finely dispersed by the combination of the improved resistance to oxidation at a high temp. by Ti, Nb and the temp. conditions for coiling of the steel sheet in the stage of hot rolling, by which the high-temp. strength after Al plating is improved.
SAKAI NORIYASU
KAWASE HISAO
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