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A529 Carbon Steel: Uses, Composition, Properties

Xomety X
By Team Xometry
July 1, 2023
 10 min read
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A529 carbon steel is a versatile and widely utilized type of structural steel renowned for its exceptional strength, durability, and usefulness for a number of construction applications. Because of its desirable properties, A529 carbon steel has proven to be an indispensable material in the realms of infrastructure, architectural construction, and industrial plant construction.

This article delves into the diverse uses, composition, and key properties of A529 carbon steel. 

What Is A529 Carbon Steel?

A529 is a type of structural steel that is commonly used in construction and infrastructure applications. It is classified as carbon-manganese steel, meaning it contains both carbon and manganese as its primary alloying elements. The carbon content of A529 steel, between 0.20% and 0.27%, puts it into the low-carbon steel category. 

One of the main benefits of A529 carbon steel is its good weldability, which makes it possible to use a range of welding techniques. It can be joined using common welding methods, such as arc welding and gas welding, without significant issues. Additionally, A529 steel exhibits good formability and machinability, allowing it to be shaped and processed into a variety of components and parts. It is primarily used for the construction of buildings, bridges, and other structures that require excellent strength-to-weight ratios. This type of steel is often used in heavy-duty applications where high load-bearing capacity is required.

The A529 steel specification encompasses several grades, including A529 Grade 50 and A529 Grade 55. The grade name indicates the minimum yield strength of the steel, with Grade 50 having a minimum yield strength of 50 ksi and Grade 55 having a minimum yield strength of 55 ksi.

What Is A529 Carbon Steel Used For?

A529 carbon steel is mainly used in construction applications. Listed below are some of its uses:

  1. Structural components such as beams, columns, and joists, which provide support and stability to the building framework
  2. Utilized in the fabrication of bridge girders, trusses, and other load-bearing elements.
  3. Components such as frames, supports, and structural members of industrial machinery, cranes, and material-handling equipment
  4. Fabrication of storage tanks and silos used in various industries
  5. Utilized for the construction of platforms, jackets, and other support structures in offshore oil and gas exploration

How Is A529 Carbon Steel Made?

A529 carbon steel is primarily produced through a process called hot rolling. This involves heating the steel billet or ingot to high temperatures and then passing it through a series of rolling mills to reduce its thickness and shape it into the desired final product. The specific production processes may vary depending on the manufacturer and the desired properties of the A529 carbon steel. The general steps are listed below:

  1. Melt the iron ore and other raw materials in a blast furnace. This process removes impurities and produces molten iron.
  2. Combine the molten iron with recycled steel or additional alloys in a basic oxygen furnace (BOF) or an electric arc furnace (EAF). These furnaces allow for precise control of the steel composition, including carbon content.
  3. Refine the molten steel either through ladle refining or degassing. This will remove any remaining impurities and adjust its chemical composition.
  4. Pour the refined molten steel into a continuous casting machine. In this machine, the steel solidifies into a long continuous slab or billet with a rectangular cross-section.
  5. Reheat the billet to a high temperature and then pass it through a series of rolling mills. These mills apply pressure to the billet, reducing its thickness and shaping it into the desired profile, such as sheets, plates, or structural sections.
  6. After the desired shape is achieved, the steel is cooled and may undergo additional heat treatments such as quenching and tempering to enhance its mechanical properties. It is then cut to the desired lengths and subjected to surface treatments, such as shot blasting or galvanizing, to improve its durability and appearance.

What Is the Chemical Composition of A529 Carbon Steel?

The chemical composition of A529 carbon steel is given in Table 1 below:

Table 1: Chemical Composition of A529 Carbon Steel
FeMnCCuSPSi
Fe
Balance (=>97.69%)
Mn
<=1.35%
C
<=0.27%
Cu
=>0.20%
S
<=0.050%
P
<=0.040%
Si
<=0.40% max

Table Credit: https://www.steel0.com/ASTM_A529_Grade_50.htm

What Is the Carbon Content of A529 Carbon Steel?

A529 steel is specified with a maximum carbon content of 0.27%.

What Are the Properties of A529 Carbon Steel?

The mechanical properties of A529 are given in Table 2 below: 

Table 2: Mechanical and Physical Properties of A529 Carbon Steel
PropertyGrade 50 [345] ImperialGrade 50 [345] MetricGrade 55 [380] ImperialGrade 55 [380] Metric
Property
Tensile Strength, min
Grade 50 [345] Imperial
70* ksi
Grade 50 [345] Metric
485 MPa
Grade 55 [380] Imperial
70 ksi
Grade 55 [380] Metric
485 MPa
Property
Tensile Strength, max
Grade 50 [345] Imperial
100 ksi
Grade 50 [345] Metric
690 MPa
Grade 55 [380] Imperial
100 ksi
Grade 55 [380] Metric
690 MPa
Property
Yield Strength, min
Grade 50 [345] Imperial
50 ksi
Grade 50 [345] Metric
345 MPa
Grade 55 [380] Imperial
55 ksi
Grade 55 [380] Metric
380 MPa
Property
Elongation in 8 in. (200 mm), % (min)
Grade 50 [345] Imperial
18
Grade 50 [345] Metric
18
Grade 55 [380] Imperial
17
Grade 55 [380] Metric
17
Property
Elongation in 2 in. (50 mm), % (min)
Grade 50 [345] Imperial
21
Grade 50 [345] Metric
21
Grade 55 [380] Imperial
20
Grade 55 [380] Metric
20
Property
Density
Grade 50 [345] Imperial
7.85 g/cm3 or 0.284 lb/in³
Grade 50 [345] Metric
7.85 g/cm3 or 0.284 lb/in³
Grade 55 [380] Imperial
7.85 g/cm3 or 0.284 lb/in³
Grade 55 [380] Metric
7.85 g/cm3 or 0.284 lb/in³

Table Credit: https://boltport.com/specifications/astm-a529/

In the case of hot rolled carbon steels, the numerical value mentioned in the designation represents the yield strength of the material up to a thickness of 16 mm. It is important for designers to be aware that as the plate or section thickness increases, the yield strength decreases. This is because thinner materials undergo more work during the manufacturing process, which leads to an increase in strength. Therefore, it is crucial to consider that the yield strength of the material will vary based on the thickness of the plate or section being used.

Machinability Rating of A529 Carbon Steel

A529 carbon steel is considered to have good machinability. Machinability is strongly influenced by material hardness. Hardness, in turn, is influenced by carbon content. The optimal carbon content for achieving the highest machinability rating is typically around 0.2%. A529 has a carbon content of around 0.27%. It is a bit higher than the carbon content for easiest machinability, but still well within the range considered machinable when the correct tools are used. 

What Are the Thermal Properties of A529 Carbon Steel?

The thermal properties of A529 carbon steel will be different for the different steel grades. The thermal properties of A529 grade 345 are outlined in the table below:

Table 3: Thermal Properties of A529 Steel Grade 345
Temperature (°C)Specific thermal capacity (J/kg°C)Mean Coefficient of Thermal Expansion 10-6/(°C) Between 20°CThermal conductivity (W/m°C)
Temperature (°C)
24
Specific thermal capacity (J/kg°C)
-
Mean Coefficient of Thermal Expansion 10-6/(°C) Between 20°C
-
Thermal conductivity (W/m°C)
-
Temperature (°C)
893
Specific thermal capacity (J/kg°C)
134
Mean Coefficient of Thermal Expansion 10-6/(°C) Between 20°C
-
Thermal conductivity (W/m°C)
31.3
Temperature (°C)
492
Specific thermal capacity (J/kg°C)
-
Mean Coefficient of Thermal Expansion 10-6/(°C) Between 20°C
42
Thermal conductivity (W/m°C)
41.2

Table Credit: https://www.steel-grades.com/metals/85/199508/ASTM-A529-A529M-A529Grade345.html

What Are the Common Forms of A529 Carbon Steel Material?

The common forms of A529 carbon steel are listed below:

Sheet

A529 steel is available in the form of sheets. Sheets are thinner than plates and are commonly used for applications where lighter weight or greater flexibility is required, such as in certain building components or decorative elements.

Bar

A529 steel can be found in the form of bars, which are long, straight metal sections with a consistent cross-sectional shape. Bars are often used in construction and manufacturing for structural supports, frames, and other load-bearing components.

Plate

A529 steel is commonly supplied in the form of plates. These plates are flat, rectangular pieces of steel with specific dimensions and thicknesses. A529 plates are often used for structural applications, such as building construction and bridge fabrication.

Hot Rolled

Hot-rolled A529 steel is produced by heating the steel billet or slab above its recrystallization temperature and then rolling it into the desired thickness and shape. The steel is malleable during hot rolling, allowing for the production of larger sections such as plates, sheets, and structural shapes. Hot-rolled steel tends to have a rougher surface finish than cold-rolled.

Annealed

Annealing is a heat treatment process that helps to improve ductility, relieve internal stresses, and refine the grain structure of the steel. Annealed steel is softer, more workable, and exhibits improved machinability.

Cold Drawn

Cold drawing is a process in which the steel is pulled or drawn through a die at room temperature to reduce its cross-sectional size. This process increases the steel's strength and hardness while improving dimensional accuracy and surface finish. The specific microstructural characteristics of cold-drawn A529 carbon steel can vary depending on factors such as the composition, processing conditions, and any subsequent heat treatments applied to the material. However, cold-drawn carbon steel exhibits a refined and more uniform microstructure compared to its hot-rolled counterpart. Cold-drawn steel is commonly used in applications that require high strength and precise dimensions, such as shafts, rods, and precision components.

What Are the Advantages of Using A529 Carbon Steel?

A529 carbon steel is a type of structural steel that offers several advantages in various applications. Here are some of the advantages of using A529 carbon steel:

  1. It has excellent mechanical strength, making it suitable for structural applications that require robust and durable materials.
  2. Compared to other high-strength steel, A529 carbon steel is relatively affordable.
  3. It possesses good weldability, allowing it to be easily joined using common welding techniques. 
  4. It finds application in a variety of industries. It is commonly used in the construction of buildings, bridges, and other infrastructure and can also be utilized in heavy machinery, equipment, and transportation vehicles.
  5. It is a standardized grade, which means it has defined mechanical and chemical properties established by industry standards. This promotes ease of specification and ensures consistency in material performance across different manufacturers.
  6. It exhibits good machinability, allowing for efficient and precise machining operations.

What Are the Disadvantages of Using A529 Carbon Steel?

While A529 carbon steel offers many benefits, it also has some potential disadvantages that should be considered. These are listed below:

  1. It is not inherently corrosion-resistant. It can be prone to oxidation and corrosion when exposed to moisture, oxygen, and corrosive environments. 
  2. Can exhibit reduced toughness and impact resistance at low temperatures, particularly below freezing. 
  3. Has relatively lower ductility compared to some other structural steels. It may exhibit limited elongation or deformation capacity before fracturing, which can affect its behavior under certain loading conditions.

What Are Equivalents of A529 Carbon Steel?

Table 4 below shows the equivalents of A529 carbon steel:

Table 4: Equivalents of A529 Carbon Steel
CountryEquivalent Grade
Country
EUROPE EN
Equivalent Grade
S275JR
Country
GERMANY DIN
Equivalent Grade
ST44-2
Country
FRANCE NF
Equivalent Grade
E28-2
Country
ITALY UNI
Equivalent Grade
FE430B
Country
US ASME / ASTM/ SAE
Equivalent Grade
A529 Gr. 42,50,55

Table Credit: https://www.universalsteelamerica.com/steel-grade-equivalents/

What Is the Difference Between A529 Carbon Steel and A514 (T1) Steel?

A529 carbon steel and T1 steel are two distinct types of steel that differ in their composition and properties. A529 carbon steel, commonly used in construction, is a low-to-medium-carbon steel containing varying amounts of carbon, manganese, phosphorus, sulfur, silicon, and copper. It offers moderate strength and is suitable for structural applications where high strength is not a primary requirement.

T1 steel (also known as ASTM A514), on the other hand, is an HSLA (high-strength low-alloy) steel designed for applications that demand exceptional strength and toughness. It contains slightly different amounts of carbon, manganese, phosphorus, sulfur, silicon, and copper than A529, and it also may contain some combination of boron, titanium, molybdenum, vanadium, and nickel in small amounts. T1 steel exhibits high tensile strength and hardness, making it ideal for applications such as heavy machinery, mining equipment, and construction machinery that require superior strength.

Regarding weldability, T1 steel can be difficult to weld due to its high carbon content. It requires special attention during the welding process due to its high strength and alloying elements. A529 carbon steel possesses good weldability and can be easily welded using common techniques without requiring preheating or post-weld heat treatment in most cases.

Summary

This article presented A529 carbon steel, explained it, and discussed its various applications and properties. To learn more about A529 carbon steel, contact a Xometry representative.

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Xomety X
Team Xometry
This article was written by various Xometry contributors. Xometry is a leading resource on manufacturing with CNC machining, sheet metal fabrication, 3D printing, injection molding, urethane casting, and more.