The introduction of metal to the shipbuilding industry helped to significantly revolutionize the industry as a whole, especially the development of stainless steel and aluminum alloys. Prior to the use of metal in shipbuilding, ships were constructed out of wood. Wood was much less suitable for ship construction because it is not durable or strong. Once metals like steel and aluminum hit the market, shipbuilders found that these were excellent materials for construction of various components of a ship.
Most Common Metal Types Used in Shipbuilding
There are a variety of metals that can be utilized in shipbuilding. When determining the best metals for ships, it is important to focus on the metal’s yield strength and tensile strength. Of the metals that fit these requirements, the most common are steel and aluminum alloy.
Steel is used with frequently in the shipbuilding industry due to its ideal mechanical properties, structural integrity and low cost. The major downside to steel though, is the fact that it is quite heavy. There are many different types of steel used in ship construction but two of the most frequently used are high tensile steel and stainless steel.
High Tensile Steel
High tensile steel is used when a metal that’s more heavy duty than regular steel is required. High tensile steel is stronger than regular steel. High tensile steel in ship construction is typically used in regions of the ship that are under high levels of mechanical stress, as well as the deck and bottom regions of larger tankers.
Stainless steel is ideal for shipbuilding due to its strength and durability. Most important is that it is non-corrosive meaning stainless steel doesn’t rust. As a result, stainless steel is perfect for the harsh environmental conditions that steel is subjected to like the harsh sunlight and saltwater.
Aluminum alloys possess beneficial properties that their steel counterparts don’t. Primarily, a ship built with aluminum alloys versus steel will be 60% lighter on average. Another benefit is that aluminum is resistant to corrosion and it is an inexpensive material to maintain. One disadvantage to aluminum alloys is that they are quite expensive for the initial cost, roughly 8-10 times more expensive than steel.
Metals Used For Different Ship Parts
Though at first glance it may seem like a ship is constructed of more-or-less the same material, ships are actually made up of a variety of different metals and metal alloys. Different metals will suit different part requirements best. Below are some of the most common ship parts and the metals they are composed of.
Shell plating is typically made of steel. During the steel ship hull construction, shell plating, creates a water-tight barrier on the bottom and sides of the ship. It typically consists of several curved and flat steel plates, welded together.
The superstructures are the part of the boat that is built up above the deck. An example of this is seen on any cruise ship. The superstructures of ships are now commonly made with aluminum alloys. This allows for the ship to be lighter as a whole than if the superstructures were made of steel, and the ship’s center of gravity is lower.
Watertight doors are doors constructed on both sides of a watertight bulkhead. These doors are typically made of cast steel and prevent water from entering the ship. It is important that steel is used because the doors need to be capable of withstanding high pressures, if they are poorly made then a ship could flood.
The stern frame supports the tailshaft of the rudder and the propeller. In old ships, the frame used to be welded to the hull. The frame is typically fashioned from steel plates with plate sides that are stiffened for added support. In order to prevent it from corroding, it is heavily coated.
Rudder pintles refer to the bolt/pin that attaches the rudder to the ship. In the past, brass pins in hardwood frames were used. But upon the introduction of steel, it was found that a stainless steel pintle is stronger and cheaper than its brass counterpart. The basic functionality of the pintle is similar to that of a door hinge.
Ship propellers are usually constructed by a copper alloy, like brass, to withstand the corrosive effects of saltwater. They are specifically designed to prevent cavitation which occurs when bubbles of water vapor collide with the propeller and create small dents. Propellers generate the propulsion force of the ship by turning in a fan-like motion.
We hope you gained insight on the functionality of steel and aluminum in shipbuilding. At Texas Iron and Metal we have a huge supply of surplus steel and metal inventory to meet your needs. If you are interested in finding out more or would like to request a quote, one of our knowledgeable salespeople would be happy to assist you.