PURPOSE: To obtain the steel sheet combining superior corrosion resistance with strength and low temp. brittleness by subjecting a builtup sandwich slab consisting of a cladding material of stainless steel, etc., and a steel with a specific composition to rolling under the prescribed conditions.
CONSTITUTION: A cladding material composed of a stainless steel or an Ni alloy, such as 'Inconel(R)', and a base material composed of a steel having a composition consisting of, by weight, 0.02-0.06% C, ≤0.5% Si, 1.0-2.0% Mn, ≤0.03% P, ≤0.005% S, 0.01-0.15% Nb, 0.005-0.03% Ti, ≤0.05% Al, 0.002-0.006% N, and the balance iron with inevitable impurities are prepared. At the time of rolling a slab assembled by laying the above-mentioned cladding material and base material one on top of the other and welding the periphery, heating is done up to 1100-1250°C and rolling is temporarily interrupted at ≥900°C surface temp., and then, water cooling is performed at 5-40°C/sec cooling rate until a surface temp. of 200-800°C is reached and air cooling is exerted for 30-500sec. Successively, after rolling is finished at ≤900°C temp. in the central part of sheet thickness, the sheet is air-cooled for 30-200sec and then cooled at 5-40°C/sec cooling rate until the surface temp. reaches an arbitrary temp. not higher than 550°C, followed by air cooling.
OGATA YOSHINORI
NISHIOKA KIYOSHI
TAMEHIRO HIROSHI
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