Mild steel, also called low-carbon steel, is one of the most commonly used types of steel. It is used in the construction and automotive industries and for fences, signs and countless other applications. It is valued for its weldability, machinability and ductility. Mild steel is mainly characterized by a carbon content of less than 0.2 percent by weight. The four-digit AISI (American Iron and Steel Institute) classification codes for mild steel begin with "10" and end with two digits less than 20, which indicates the approximate carbon content of the steel in hundredths.
This article examines the chemical composition, mechanical properties, grades and properties of mild steel.
What is mild steel?
Mild steel is an iron alloy with carbon as the main alloying element. It is one of the most commonly used steels and can be used for a number of general purposes. Mild steel owes its popularity to its sufficient strength at low cost, in addition to its excellent machinability and weldability. Different grades of mild steel have different amounts of higher carbon content that struggle with increased strength at the expense of ductility. In some cases, additional alloying elements are added to improve properties such as tensile strength, corrosion resistance and wear resistance. Figure 1 shows some examples of mild steel products:
What is the composition of mild steel?
Mild steel consists of an iron (Fe) base with the addition of small amounts of carbon. Low carbon steel is generally defined by ASM International as steel with less than 0.2% carbon. Different types of mild steel are defined by their different carbon levels. Another common alloying element is manganese (Mn).
What are the Different Types of Mild Steel?
There are many different grades of mild steel. Mild steels classified according to the AISI (American Iron and Steel Institute) numbering system all start with "10" as the first two digits, indicating their low carbon content. Low carbon steels, and by extension mild steels, will have the last two digits of the designation as a number less than 20 (estimated carbon content multiplied by 100). Most mild steels contain low (<1%) amounts of phosphorus and sulfur, and these elements are actively limited because they are considered impurities. Some common figures are listed in Table 1 below:
How much carbon is in mild steel?
The amount of carbon in mild steel is less than 0.2% by weight. According to AISI (American Iron and Steel Institute), low-carbon steel is a type of mild steel.
What are the mechanical properties of mild steel?
The mechanical properties of some common mild steels are shown in Table 2 below:
What is the density of mild steel?
The density of all types of mild steel fluctuates around 7.8 c/cm3. This is because the density of mild steel, which is more than 98% iron, is dominated by the density of iron (7.87 g/cm3). Alloys that fit under the mild steel umbrella and that contain small amounts of alloying elements other than iron will have slightly different densities.
What is the hardness of mild steel?
Mild steel is both tough and strong and therefore a very tough material. The toughness of mild steel varies depending on its type and classification. Toughness is defined as the amount of energy that can be absorbed without breaking. It is calculated as the area under the stress-strain curve of a material as defined up to the breaking point. The mechanical property commonly used to define the toughness of a material is the Charpy impact strength. For example, for 1020 the Charpy impact strength would be 24 J at 10 °C.
Which grade of mild steel is the strongest?
The strongest grade of mild steel is 1020. It should be noted that this grade of mild steel also has the highest carbon content, giving it strength at the expense of ductility.
What is the high melting point of mild steel?
The temperature at which mild steel becomes fully liquid varies between 1450 and 1530 °C, depending on the carbon and alloy content of the steel in question.
Is mild steel suitable for welding?
Yes, mild steel is suitable for welding. Grades with additional silicon and manganese further improve the weldability of mild steel. The weldability of mild steel is one of the reasons for its widespread use as it can be easily welded on site with a simple shielded metal arc welding machine using ER70S-3 and ER70S-6 rods.
If you would like to learn more about which mild steel is best suited for your unique application, contact a Xometry expert today or view ourcitation tool.
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This article introduced mild steel, explained what it is and discussed its various properties. Would you like to know more about mild steel,Contact a Xometry representative.
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