| 摘要 |
PURPOSE:To improve corrosion resistance, coating property under severe corrosion circumstance, by forming substrate plated layer of Ni, Co or Ni-Co alloy on Cr bearing steel sheet, then forming covering layer of Zn alloy contg. 1 or 2 kinds among Ni, Fe, Co, Mo to Zn. CONSTITUTION:Steel sheet contg. <0.10% C, 0.005-0.08% sol. Al, 0.2-10% Cr, or further 0.03-0.5% 1 or >=2 kinds among Ti, Nb, V, Zr respectively is pretreated i.e. degreased or pickled, then substrate plated layer of Ni or Co or Ni-Co alloy is formed. This is heated to 600-850 deg.C in nonoxidizing atmosphere, and the plated surface is made to diffusion treated layer of Ni-Fe, Co-Fe, Ni-Co-Fe, etc. Thereon, plated layer of Zn alloy contg. 7.5-30% 1 or >=2 kinds among Ni, Fe, Co, Mo is formed to Zn by 1.5-8mu thickness. Steel sheet superior in corrosion resistance, costing property under severe corrosion circumstance can be manufactured. |
