| 摘要 |
PROBLEM TO BE SOLVED: To provide an electrolytically surface roughened steel sheet having the good adhesion property of coating films in ordinary steel and special steel exclusive of stainless steel. SOLUTION: This surface roughened steel sheet is constituted by forming the electrolytically roughened surfaces of 1.0 to 4.0μm in arithmetic mean deviation of profile Ra, more preferably <=25μm in maximum height, and further preferably 0.03 to 0.1 mm in average spacing Sm of ruggedness on the surfaces of the steel sheet of the ordinary steel or special steel containing <=2.0 mass% Cr, <=5.0 mass% Ni and <=1.0 mass% Mo. The steel sheet can be manufactured by subjecting the steel sheet to an anode electrolysis for 5 to 12 seconds at a current density of 50 to 150 A/dm<2> while generating gaseous oxygen bubbles on the surfaces of the steel sheet with the steel sheet of the ordinary steel or special steel as an anode electrode of a potential of +1.5 to +2.2 V in a mixed aqueous solution of a nitric acid and a strong electrolytic nitrate, for example, an aqueous solution containing 5 to 30 mass % nitric acid and 50 to 100 g/L sodium nitrate at 20 to 40 deg.C.
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