| 摘要 |
PURPOSE:To develop Pb-Sn alloy plated steel sheet superior in corrosion resistance and of small Fe dissolution from defective plated part, by forming substrate plated layer of Ni, Co or Ni-Co alloy on Cr bearing steel sheet, then plating Pb-Sn alloy thereon. CONSTITUTION:Cr bearing steel sheet contg. <0.10% C, 0.005-0.08% sol Al, 0.5-20% Cr or further 0.03-0.5% one or >=2 kinds among Ti, Nb, V, Zr respectively is pretreated, i.e. degreased or pickled, etc., then substrate plated layer of Ni, Co or Ni-Co alloy is formed. Next, said sheet is heated to 600-850 deg.C in nonoxidizing atmosphere, to change the plated surface to diffusion treated layer of Ni-Fe, Co-Fe, Ni-Co-Fe, etc. Pb-Sn plated layer contg. 7-15% Sn is formed by 2-10mu thickness on surface of the substrate diffusion treated layer. Dissolution of steel sheet from pinhole of plated layer is prevented, and Pb-Sn alloy plated steel sheet superior in corrosion resistance is manufactured. |
