Manufacturing light weight vehicles is a major trend in automotive industry. It is dictated by increasing requirements for emissions, which are constantly getting stricter. Automotive manufacturers are taking different approaches to achieve ultimate weight, composite materials, such as carbon fibre, are being used as well as aluminium. But another part of this quest is to maintain vehicle’s compatibility with safety requirements and manufacturing a rigid vehicle.
Where strength is needed, steel is usually used. Now scientists at Missouri University of Science and Technology have developed a high-strength steel, known as a “third-generation advanced high-strength steel”. It is created particularly with automotive industry in mind and its task to reduce emissions. Car manufacturers are already implementing improvements in exhaust treatment systems, transmission efficiency and aerodynamics, but light weight technologies are crucial to reach this goal.
Dr. Ronald J. O’Malley noted that scientists are still working with this new steel. They are “currently refining the steel design to achieve ‘Gen 3′ mechanical property goals while also maintaining manufacturability”. He also added that this is one of the most promising generation-three steels he has ever seen. Currently car and truck makers mostly use first-generation steel. There is, of course, a second-generation steel already developed and it is stronger and lighter than the first-generation material, but it is too costly to produce and more difficult to manufacture.
This new third-generation steel still being developed at Missouri University of Science and Technology is thought to be lighter, easier to manufacture and strong enough to address automakers’ safety concerns. Automakers have to make vehicles light and efficient, but to address requirements for safety as well.
For example, making a perfectly aerodynamic shape might be possible, but then car may not be safe enough in case of collision with pedestrians. Similarly, making cars extremely light and cheap is possible, but safety requirements require certain strength and rigidity in the chassis of the car, which asks for strong materials.
To create such steel that would meet the needs of the automakers, scientists are using a method known as TRIP or transformation-induced plasticity. This technique involves the transformation of an unstable crystal structure known as austenite, which normally exists in steel at high temperatures, into martensite, a harder substance that develops as the steel deforms. In fact, scientists are using a two-stage or ‘dual TRIP’ mechanism, which is intended to help automotive industry to reach emission goals as well as to maintain safety. Scientists are also using an atomic modelling method, known as density functional theory, to identify alloying elements to create the dual TRIP character of these new steels.
However, there are still challenges in the way of using this new steel in real life application. There are still questions about large-scale production of these new steels. University is working with industrial partners to test the properties of the steel as well as to examine the whole manufacturing process from melting to manufacturing the automotive parts.
These are very welcome news for automotive industry as lightweight materials are crucially needed for the cars of tomorrow. Requirements for emissions are getting stricter and ordinary cars are already using materials that would be commonly found in supercars. Therefore, new strong and lightweight steel could help manufacturers to meet new requirements, while still maintaining rigidity of the vehicle and safety of passengers.