With all the possibilities of technical advancement, there are endless ways to be innovative these days. With that in mind, what is the significance of technology and innovation in shipbuilding? We can go back to the American Civil War in 1862, wherein two ironclad warships battled for the first time. Not one ship sunk; thus, both parties claimed victory.
For naval technology, this was an important milestone. Why? Because ironclad warships had shown an increase in survivability compared to their wooden-hulled predecessors. Presently, the battlefield is evolving faster than ever and the need has emerged for a new breed of warships with increased speed, agility, and stealth.
Look no further! The answer is aluminum.
5xxx aluminum alloys
Aluminum allows vessels to be made lighter and faster at one-third the density of steel. The corrosion resistance and strength of new alloys, especially the 5xxx series of aluminum alloys, make it an ideal choice for constructing sea-going vessels. Adding elements to pure aluminum produces a chemical composition with improved properties creating an aluminum alloy that increases strength. A 4-digit number is then assigned in which the first digit represents a general series that characterizes its main alloying elements.
The primary agent for the 5xxx series is magnesium which gives the alloy strength and good weldability, amongst other things. In naval ships alone, 6,000 tons of aluminum are used each year on destroyers. For more than a decade now, 5456 plate and extrusions have become the benchmark for the welded deckhouse structures of destroyers. The weight-saving ability of the 5xxx series allows the ship to maintain stability with a narrow hull that is crucial in reaching high speeds.
Advantages of 5xxx aluminum alloys
The structures save 55-67% of their weight by using a 5xxx aluminum alloy. The ships can increase payload, haul more equipment, and lower the energy required to power the boat. The 5xxx series has good weld ductility without post-weld treatments due to the weld yield strengths of 100-200 MPa. It has lower corrosion resistance which is ideal for any structure encountering water or chemicals. The tensile strength of the alloy showed reductions of only 2-5% throughout a 10-year seawater test.
Friction stir welding for marine vessels
The growth of new metal forming processes, friction stir welding (FSW) chief among them, has made aluminum one of the most versatile materials, creating profiles. For more than twenty years, friction stir welding or FSW has been a highly effective alternative to traditional MIG welding in marine applications. It is best used on long straight welds for a more cost-effective and efficient operation.
Several of the welded structures in this process are alloyed aluminum extrusions. Flat designs used in the marine industry, such as floors, decks, bulkheads, and parts that do not require complex curves, can be done by FSW. These vessels are capable of speeds of more than 45 knots (51 mph), an exceptional rate for vessels that weigh 3,500 tons. Even hull sections are critical to making the vessels lighter, faster, and more maneuverable.
Benefits of friction stir welding for marine vessels
Speeds up the building procedure and saves money for large and small projects.
The cost savings come from eliminating the required person-hours of traditional MIG welding and providing a more substantial, higher quality weld, which cuts down on secondary repair costs. Using complete components such as modular FSW panels reduces the time and labor costs of measurements and cutting on the construction site. There is also minimal distortion on the weld and better aesthetics. It is more environmentally friendly (no UV radiation or fumes) and more user-friendly.
Removes flaws that are inherent to conditional welding methods.
Characteristics include no porosity, no hot cracking, and a more robust fusion of the constituent elements. Becoming adopted far and near, FSW is less susceptible to errors due to the automated process.
Aluminum can help marine manufacturers and shipbuilders obtain weight and production savings and improve the quality and efficiency of vessels and structures… and the unique qualities of extruded aluminum component design provides exceptionally high torsion strength resistance – making it the ideal material for marine application.
Taber continues to extrude billet in a wide range of alloys and sizes. It also has diversified its markets beyond the military since its inception to include aerospace, automotive, marine, infrastructure, and sporting goods, among many others. With in-house casting solutions, ultra-precision extrusion manufacturing, friction stir welding capacities, and a full range of hard and soft aluminum alloys, Taber aligns itself as an industry leader in having the broadest available capabilities.
Today, Taber Extrusions is proud of its recently added VF-12 CNC machining line and a complete offering of extruded aluminum components, value-added machining services, and raw material supply to the North American market. Adding these capabilities to a growing portfolio drives Taber into the future in a pursuit to continuously enhance the quality and service we provide to our customers.
The applications of the 5xxx series aluminum alloys range from shipping containers to their most prolific application, boats. Whether building a recreational boat, commercial ship, or naval vessel, the advantages that the 5xxx series of aluminum alloy have, make it the premier building material for anything marine related. Before we ‘dive’ into the specific advantages of the 5xxx series and it applications, lets break down what aluminum alloys are and what sets the 5xxx series apart.
What is an aluminum alloy and what does it mean when an alloy is considered part of the 5xxx series?
Simply, an aluminum alloy is created by adding elements to pure aluminum, creating a chemical composition that has enhanced properties (typically to increase strength). Once these compositions are created they are assigned a 4-digit number where the first digit signifies a general series that characterizes its main alloying elements. For the 5xxx series, its main agent is magnesium which gives the alloy high strength as well as good weld ability amongst other things.
What are the advantages of 5xxx aluminum alloys?
Weight Saving: By using 5xxx aluminum alloy, structures save an average of 55 to 67% of their weight. With comparable strength to mild steel, the alloy’s ability to decrease a structures weight can be hugely beneficial, especially for marine vessels. By saving weight the boats can increase payload, haul more equipment, and lower the amount of power required to power the boat.
Weld ability: With weld yield strengths of 100 to 200 MPa, the 5xxx series have good weld ductility without post weld heat treatments.
Corrosion resistance: The 5xxx series has lower resistance to corrosion making it ideal for any structure that will be coming in contact with water or chemicals. Through a 10-year seawater test, the tensile strength of the alloy showed reductions of only 2 to 5%.
What are the marine applications of 5xxx Series Aluminum Alloys?
Pleasure Boats: Made from both 5xxx and 6xxx series aluminum alloys, pleasure boats utilize the alloys ease of fabrication, corrosion resistance, and cost effectiveness for building their hull or other equipment.
Commercial ships: Many passenger vessels utilize the 5xxx series for both superstructures and equipment; ranging from 1000 to 2000 tons per ship. Since for many ocean liners appearance is important, the structures are painted but aluminum allows for a 50% longer time frame till repainting.
Naval Vessels: Each year, 6000 tons of aluminum is used on destroyers. Within the past decade, 5456 plate and extrusions have become the standard for the welded deckhouse structures of destroyers. The weight saving ability of the 5xxx series allows the ship to maintain stability with its narrow hull that is needed to reach high speeds. Beyond the main structure, the alloy can also be employed for a variety of equipment including doors, windows, gratings, lockers, bunks, etc.
It is the use of the aluminum alloys that has allowed the marine industry to undergo a technological revolution. While the aluminum may have an initial cost premium, its ability to create lighter ships with lower maintenance costs means that the ship will be a worthwhile investment over the course of its life. And though boats may not be the first thing you think of when discussing the application of an aluminum alloy, the 5xxx series aluminum alloy has transformed the marine industry for the better.