| 摘要 |
PURPOSE:To improve the resistance of a cold rolled steel sheet to secondary working embrittlement by a box annealing method by adding a specified amount of Sb, As, Ge or Se to a steel having a specified composition contg. combinedly added Ti and Nb. CONSTITUTION:A steel consisting of <=0.008% C, <=0.10% Si, <=0.50% Mn, <=0.05% P, 0.01-0.10% Al, <=60ppm N, 4.00[C]+3.43[N]<=0.06% Ti, 0.002-0.040% Nb, 0.005-0.020% Sb, As, Ge or Se and the balance Fe is prepd. The steel is hot rolled, descaled, cold rolled and box-annealed at the recrystallization temp. or above. The resistance of the resulting cold rolled steel sheet to secondary working embrittlement is improved by the addition of 0.005-0.020% Sb, As, Ge or Se but <0.005% Sb, As, Ge or Se does not show the effect and >0.020% Sb, As, Ge or Se increases segregation on the grain boundaries and deteriorates the resistance to secondary working embrittlement.
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