Automotive High-strength stainless steel motorcycle frame developed

A pioneering stainless steel racing motorcycle has been developed by Highland Group and Outokumpu. The bike showcases the potential of high-strength stainless steel for the transportation industry.

This year at Scandinavia’s largest subcontractor trade show, Elmia, there was a real crowd catcher at the Outokumpu exhibition booth. On display was a prototype racing steel motorcycle by Highland Group of Sweden, custom-designed and manufactured with the help of Outokumpu using high-strength grades of stainless steel. The steel motorcycle, named Highland 450cc Supermoto, has drawn a lot of worldwide attention after Martin Lind of Sweden rode the bike to finish in second place at the Swedish Supermoto 2008 championship. With the help of the pioneering bike, he also clocked up a number of wins in the United States. The problem Supermoto is a combination of motocross and road racing, where the racing course alternates between a racing track and a dirt section in the infield. The motorcycles combine road-racing and off-road features. Compared to normal motorcycle racing, the tracks are short, twisty and incorporate high jumps. This means that manufacturers need to consider many other features aside from outright machine performance. Highland Group is a spearheading motorcycle design house that develops complete motorcycles for established brand owners. In early 2006, Highland were looking for a new focus in their product development. For them, Supermoto presented the ultimate environment to test motorcycle performance against stress, shock and fatigue loads. Their first idea was to develop a new motorcycle frame replacing carbon steel with aluminum. But when Outokumpu’s R&D unit for automotive applications, Prinox, caught wind of Highland’s ambitions, they jumped in, and suggested that Highland introduced high-strength stainless steels as optimal materials to create a frame with superior stiffness and strength. Highland was convinced by the pitch and saw the benefits of using Outokumpu’s high-strength stainless steels to create a superior steel motorcycle. The solution Highland engineers lacked experience with stainless steel, so they partnered with Prinox in product development. As a result of the partnership, a complete prototype steel motorcycle with a stainless steel chassis was presented at the Milan Motorcycle Fair in November 2006, nine months after the beginning of the product development process. The main frame of steel motorcycle Highland 450cc Supermoto is in austenitic HyTens1200®, and the engine cradle and rear sub-frame are in duplex LDX 2101®. The chassis weight is 20 percent less than that of the best rivaling motorcycles. The precisely tuned chassis stiffness gives Highland 450cc Supermoto steel motorcycle additional competitive advantage over its competitors. A number of factors put a stainless steel motorcycle frame at a distinct cost advantage over an aluminum frame. For example, austenitic high-strength stainless steel has excellent formability in the cold conditions. But aluminum requires lengthy procedures and elevated temperatures to transform it to a state where it can be used for applications such as this. Stainless steel also requires no surface treatment, whereas aluminum requires anodizing. HyTens® stands for high-strength austenitic stainless steel grades specifically developed for the needs of automakers. Among their many benefits, HyTens® products can reach strengths many times higher than carbon steel in cold deformation, allowing considerable weight savings in structural components. HyTens® is highly formable, putting few limitations to component shapes. The engine cradle and rear sub-frame of Highland 450cc Supermoto steel motorcycle are made from LDX 2101® square tubing. This is the first tubular application of this duplex grade. It features a combination of high strength and formability unmatched by competing tubular products. It is expected to find many uses in the automotive and other sectors, according to Stefan Ekblad of Prinox. The result The success of Highland 450cc Supermoto steel motorcycle, on and off the track, is a testament to Outokumpu’s strength as providers to the transportation industry. Supermoto racer Martin Lind comments on his ride: “The Highland bike is very stable, yet nimble and easy to flick from side to side in turns. This is because we have achieved a favorable distribution of stress throughout the frame. Also, we have managed to reach a very low frame weight and, as a result, achieved a low center of gravity.” He continues: “A major difference from my previous bikes is that this one is very predictable in its response when you’re over the limit. You don’t get into trouble as easily on this bike as you do on the competition.”

Martin Lind on Highland 450cc Supermoto. Courtesy of Highland Group Highland 450cc Supermoto at Elmia 2008 The stainless frame of Highland 450cc Supermoto. Courtesy of Highland Group Elmia is the largest subcontractor trade show in Scandinavia, catering for the needs of all manufacturing industries. There were more than one thousand exhibitors at the Elmia show of November 2008, among them Outokumpu as the only stainless steel producer. Visitors numbered approximately 15,500.