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What Is Cast Steel?

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  • Written By: Angie Bates
  • Edited By: John Allen
  • Last Modified Date: 01 September 2014
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Cast steel is a type of metal created by heating iron using a crucible container. Its creation was due to a revolutionary process invented by an Englishman, Benjamin Huntsman, the 1751. Cast steel allowed for a more uniform composition of, and fewer impurities in, steel than any previous manufacturing process. Since it is made in a crucible, cast steel is often called crucible steel.

Steel is made by combining iron with carbon or other alloys. Iron is a soft metal, so not ideal for many construction purposes. The creation of steel removes many of the impurities in iron, which allows steel to be harder and more durable. The better the steel, the more iron impurities that are removed.

Early steel was made by adding small amounts of carbon to iron. For example, blister steel was made by repeatedly heating wrought iron and charcoal together in a kiln. The charcoal's carbon transfered to the steel by the process of diffusion.

Cast steel was the first type of steel that allowed alloys to be added to the iron. Prior to this method, manufacturers had not been able to get steel hot enough to melt. By heating blister steel in a clay crucible placed directly into a fire, Huntsman allowed the metal to reach up to 2900°F (1600°C). Melting allowed other elements, such as nickel, to be mixed into the metal, thus strengthening the steel.

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Over the centuries, improvements in the crucible process have been made, though the steel is still heated by fire and inside a clay, pot-shaped crucible that can be sealed. Modern cast steel is use in engines and machines, as well as ship building. It tends to be more expensive than other types of metals used for similar projects.

Cast steel has a rough finish. It often has surface holes created by gas bubbling during the heating process. An elastic metal, this type of steel is very tough, having four times the tensile strength of cast iron. Tensile strength is how much pressure, created by pulling, an object can withstand before it breaks.

One concern when using cast steel is whether the surface holes extend into the interior of the metal. If so, these holes could create weaknesses that affect the soundness of the steel. Measuring the volume of water that can be poured into the holes will give a good indication of whether the holes extend far into the metal.

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chivebasil
Post 4

You have to figure that if cast steel is used in engines and ship building it must be one of the strongest substances on earth. There are few environments that receive as much stress and strain as these.

People sometimes underestimate the concussive power of the sea, but ships have to be extremely strong in order to withstand all the force they get barraged with over the course of a voyage. There is a reason they build them out of cast steel. They have to be that strong.

nextcorrea
Post 3

I find it curious that they test for the depth of the holes in the steel by pouring water into them. There is just something so simple and obvious about this method that is seems out of step with the complicated process of making the steel itself. But I guess if it works it works. It doesn't take a computer or a robot to do everything.

whiteplane
Post 2

Most of probably have a cast iron skillet at home. Imagine how hard and solid this feels when you pick it up in your hand. It feels like you could smash through a brick wall with one if you swung it hard enough. Now imagine that cast steel is 4 time stronger than this. That is amazing. A part of me wishes I had a cast steel skillet.

backdraft
Post 1

It never fails to amaze me how advance and technical scientists working hundreds of years ago were able to be. Imagine trying to forge metal and perform complicated experiments on its properties all the way back in 1751.

I realize that steel has been around for a long time, but somehow it just seem like one of those contemporary products that was completely out of reach for people living just a few hundred years ago. It just goes to show that human ingenuity is almost limitless. If a person is curious about something they will go to almost any length to find answers.

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