Honda R&D developed a lead-free fuel tank. It combined plated steel sheet with excellent corrosion resistance, formability and productivity with a low-temperature soldering material, aiming to maintain productivity using existing equipment.
As a lead-free technology for fuel tanks, plated steel sheet using a hot-dip tin-zinc alloy containing 8% Zn, with excellent corrosion resistance, formability and productivity, was developed. In addition, a tin-silver alloy containing 3.5% Ag, with excellent low-temperature solderability and resistance to galvanic corrosion with the plating, was adopted as the soldering material.
A manufacturing technology challenge was identified: continuous spot weldability declined to approximately half the current level. The cause was electrode deterioration resulting from an alloying reaction between the electrode metal and plating metal. Improvements were made by controlling plated-surface resistance, reducing welding current and optimizing the electrode-tip geometry.
This enabled overall performance, including corrosion resistance, press formability and weldability, to be improved while maintaining productivity equivalent to the current level with existing equipment.
The paper was published in Vol.12 No.2 of Honda R&D Technical Review. Information on the related paper is provided on the journal's publication page.