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A Guide to Marine Grade Metals
Water is relentless. It wears down metal over time through pressure, corrosion, and bacteria growth. That's why cargo ships, naval ships, and cruise ships must be built with durable marine grade metals.
These are the metals and metal alloys that have the best chance to withstand the threats of the open sea.
Stainless, galvanized, carbon, and alloy steel are all suitable for marine use. Stainless steel contains molybdenum, which helps resist the corrosive effects of saltwater, pitting in particular. The higher the percentage of molybdenum, the better.
Stainless steel type 304 is the most versatile and widely used, as it minimizes carbide precipitation and can withstand scorching temperatures. In addition, type 316 contains notable contents of molybdenum and nickel, giving it a better overall corrosion resistance than 304.
Carbon steel, in certain forms, passes the saltwater test. It needs the assistance of alloys such as chromium and manganese to ensure the appropriate strength and corrosion resistance.
Applications: Boat propeller shafts, storage vessels, marine fittings, shipbuilding
Marine brass – also referred to as naval brass – often blends with tin, zinc, or lead to improve its sea qualities. Tin and zinc improve corrosion resistance, while lead enhances the metal's maneuverability. Brass can withstand extreme heat as well, making it useful in piping or as a condenser.
Applications: Shafting, piping, marine fasteners, motors, pumps
Copper provides good corrosion resistance and ductility. It's commonly used for underwater tubing. However, copper is not the strongest metal. That's why it often relies on elements like nickel and manganese to strengthen its durability.
Unlike other metal alloys, copper's alloys contribute a high resistance to biofouling, meaning damage to piping caused by organisms such as barnacles and algae.
Applications: Tubing, water lines, heat exchange tubes, valves, desalination equipment
Aluminum offers tremendous strength and durability, plus it's a lower weight option compared to steel. The metal is frequently used to build the body of a ship. Aluminum optimizes its corrosion resistance by mixing chromium, magnesium, or silicon alloys. It's one of the more widely used marine metals.
Applications: Shipbuilding, docks, boat hulls, shipyard infrastructure
Aluminum-bronze and silicon-bronze were created for marine use. Bronze and its aluminum alloy are tarnish-resistant and benefit from low oxidation rates at high temperatures. The combination is also resistant to corrosion, and it fights off disruptive organisms like algae and mussels. Silicon adds strength to bronze and contributes to the metal's corrosion resistance as well. Overall, bronze is a popular material for boat propellers, as it produces little friction against other metals.
Applications: Marine fasteners, pipes, propellers
Get your hands on these precious marine metals through Industrial Metal Supply. Aluminum, steel, stainless steel, brass, copper, and silicon-bronze are available. We have what you need to get your project underway. We offer plenty of services to give you a head start, too.