| 摘要 |
PURPOSE:To improve the corrosion and heat resistances of a Cr steel material for a fuel exhaust pipe system by forming a diffusion coated layer of Ni, Co or an Ni-Co alloy and a plated layer of Ni, Co or an Ni-Co alloy on the steel material contg. optionally Ti, Nb, Zr or V. CONSTITUTION:The diffusion coated layer of Ni, Co or an Ni-Co alloy and a plated layer of Ni, Co or an Ni-Co alloy are formed on a Cr stainless steel material consisting of, by weight, <=0.02% C, 3-20% Cr, 0.005-0.10% acid-sol. Al and the balance Fe with inevitable impurities or further contg. 0.03-0.5% one or more among Ti, Nb, Zr and V. The plated layer may further contain one or more among P, Mo and Cr. By this surface treatment, corrosion from the defective part of the plated layer is reduced, and the corrosion and heat resistances of the steel material are improved.
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