Laser welding technology may hold the key to building lighter, sturdier, and more fuel efficient ships. The German firm Laser Zentrum Hanover (LZH) is leading a joint project to develop a laser welding process that will let shipbuilders use advanced materials like hybrid steel aluminum to significantly reduce the weight of these titanic vessels without compromising quality.
The hulls, superstructures and other components of many ships are already made with steel and aluminum, and this has gone a long way in reducing the weight of these massive vehicles. Not only has this improved fuel efficiency, but the lighter vessels have a lower center of gravity that improves stability. Unfortunately, the aluminum and steel pieces of the superstructure must be joined using an adapter piece and explosive cladding. Explosive cladding, in which two metals are joined using the speed and force from carefully placed explosives, is a complicated and expensive joining process.
Until recently, more efficient heat-based welding processes that could replace the cladding process were too risky to use on ship components because of the potential weakness of seams made of hybrid-steel aluminum. The problem is, when steel and aluminum are welded together, the seam they form tends to become brittle and can crack under stress. Brittle seams can be especially dangerous at sea, where they’re exposed to extreme conditions and salt water.
Engineers at Ohio State University recently developed a method to join difficult-to-weld dissimilar metals such as aluminum and steel, a method that may revolutionize welding in the auto industry. And NASA has turned to friction stir-welding in order to use advanced materials and alloys in their spacecraft. For ships, however, a solution has been harder to come by, especially given that the weight and balance of each component is so critical to the ship’s ability to stay afloat. Yet in times of scarcity and environmental degradation, fuel efficiency and ecological footprint can be just as important.
The ten-company partnership led by LZH plans to use laser welding technology to render explosive cladding in ship construction obsolete, replacing the complicated process with precision laser welders capable of fusing aluminum and steel without creating dangerous, brittle seams.
The partnership behind the research, funded by the German Federal Ministry for Economics and Energy, is in the process of developing a specialized laser welding head that can precisely control the depth of the beam’s penetration. This control will allow researchers to analyze the structural strength of different ratios of mixed steel and aluminum, as well as how the structure of these hybrid seams are affected by the depth of laser penetration.
The research group hopes to use these lab tests to develop a robust and reliable laser welding process to join steel and aluminum ship components. In short, find an ideal recipe of steel, aluminum and laser penetration depth to form a lightweight, reliable seam that isn’t too brittle for use at sea.
If you are interested in learning about laser beam welding and/or other high energy processes, stay tuned for the release of Welding Fundamentals II in 2016. This interactive, online course will cover laser beam welding, electron beam welding, plasma arc welding, and resistance welding. Like all AWS online courses, Welding Fundamentals II will feature audio narration, animated graphics and video footage that make even the most complex topics engaging and easy-to-understand.
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