Difference between revisions of "Steel"
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The two main types of steel are carbon steel and alloy steel. | The two main types of steel are carbon steel and alloy steel. | ||
| − | Carbon steels are alloys of iron and carbon with other elements not exceeding specified maximum fractions (which vary by element). Mild steel is on the low end of carbon content and is often used for structural purposes. Medium- and high-carbon steels are increasingly harder but more brittle. High-carbon steel can be used for hard tools such as knives or screwdrivers and | + | Carbon steels are alloys of iron and carbon with other elements not exceeding specified maximum fractions (which vary by element). Mild steel is on the low end of carbon content and is often used for structural purposes. Medium- and high-carbon steels are increasingly harder but more brittle. High-carbon steel can be used for hard tools such as knives or screwdrivers and is more elastic, making them suitable for springs. However, alloy steels are often used for these applications. |
The most significant type of alloy steel is stainless steel, which is an alloy of (typically in this order) iron, chromium, usually but not always nickel or vanadium and, lastly, carbon. When exposed to air, a layer of chromium oxide forms on the stainless steel and helps to prevent rust. This comes at the cost of significantly weakening the steel, which can be partially alleviated by the addition of either nickel or vanadium. Stainless steel has an improved resistance not just to oxygen, but to chemical corrosion in general. | The most significant type of alloy steel is stainless steel, which is an alloy of (typically in this order) iron, chromium, usually but not always nickel or vanadium and, lastly, carbon. When exposed to air, a layer of chromium oxide forms on the stainless steel and helps to prevent rust. This comes at the cost of significantly weakening the steel, which can be partially alleviated by the addition of either nickel or vanadium. Stainless steel has an improved resistance not just to oxygen, but to chemical corrosion in general. | ||
Revision as of 03:42, 4 February 2013
Steel is an alloy of iron. It is a material with high strengh that is widely used on Earth for construction. It is technologically well known.
Steel consists mainly of iron and is distinguished by its carbon content, and can be produced on Mars from local resources. The carbon part can be from 0,02% to 2,06%. Other additives include nickel, aluminium, calcium, silicon, manganese, chrome, vanadium, molybdenum and tungsten. The percentage of the parts decide upon the properties of the steel. The tensile strength varies from 250 MPa to more than 2000 MPa. It can be recycled easily by melting and forging for new parts.
The low quantity of oxygen in the martian atmosphere and the absence of liquid water means that exposed steel may be less prone to rust.
Terminology
Since ancient times, hard ferrous metals suitable for weapons were known (in the terms appropriate for the language) as steel whereas iron was used for softer ferrous metals. The meanings were changed in the beginning of the 20th century, so that steel was used only for ferrous metals within a certain band of carbon content. Below that, it is known as iron and above it as cast iron. The element also retains the name iron.
However, usage in industry is not always technically correct. Steel producers may use terms such as ultra-low carbon steel for low-carbon iron alloys. The term soft iron also refers to low-carbon iron.
Use cases
Steel can be made with a deliberate set of properties, making is usable for
- a great variety of housings and construction beams
- tools with low abrasion properties
- steel cable with high tensile strength
Types of steel
The two main types of steel are carbon steel and alloy steel.
Carbon steels are alloys of iron and carbon with other elements not exceeding specified maximum fractions (which vary by element). Mild steel is on the low end of carbon content and is often used for structural purposes. Medium- and high-carbon steels are increasingly harder but more brittle. High-carbon steel can be used for hard tools such as knives or screwdrivers and is more elastic, making them suitable for springs. However, alloy steels are often used for these applications.
The most significant type of alloy steel is stainless steel, which is an alloy of (typically in this order) iron, chromium, usually but not always nickel or vanadium and, lastly, carbon. When exposed to air, a layer of chromium oxide forms on the stainless steel and helps to prevent rust. This comes at the cost of significantly weakening the steel, which can be partially alleviated by the addition of either nickel or vanadium. Stainless steel has an improved resistance not just to oxygen, but to chemical corrosion in general.
See also
Open issues
- How can steel be made from local Martian resources? Probably, this is not done in a conventional furnace with coke, and hence the steel plant does not need to remove the carbon excess from the raw iron. However, smelting iron from iron ore without carbon is very difficult. Meteoric iron may be a good raw material for steel or wrought iron. It can be used directly: it does not require smelting.
