A carefully drilled 1mm hole in the rear mid-frame of a 12 year-old Duple 425 coach has provided rather unusual evidence of the zero-corrosion performance of a high-performance stainless steel. Water, trapped inside sections of the Cromweld stainless steel tube frame following the corrosion of mild steel body panel fastening screws, was perfectly clear when engineers at Blackpool Design Engineering drained the tubing during the early stages of refurbishment of the 900,000-mile vehicle. Blackpool Design Engineering Director John Mollart said: “We were amazed to discover clear water pouring out of the tubing when we tilted the coach during a routine inspection. The water had obviously built up over the years after the body panel fastening screws had corroded and sheered off. “Had the frame being made of mild steel, not only would the water have been discoloured, but the frame would probably have disintegrated as well. It is further evidence of the benefits of using this remarkable material”.
Manufactured from 3CR12, a 12% chromium stainless steel, the body structure of the 1989 Ellison Coaches owned Duple 425 was perfect, showing no signs of corrosion whatsoever, despite almost one million miles arduous and continuous service.
3CR12 stainless steel is chosen as an optimum material in many vehicle designs, sometimes as the main material of construction for chassis, frames, doors, floors and side panels, or as a secondary material in particular corrosion zones or areas where extra strength is required.
Developed to provide a superior alternative to coated carbon steels and other materials which have poor corrosive/abrasive resistance, 3CR12 offers the user the benefits of such resistance in addition to its strength, durability and low maintenance. And all this in a material that offers good weldability and formability, thus allowing fabrication by conventional means.
