A36 vs. A572: Grade Comparison
ASTM A36 and ASTM A572 are two popular types of structural steel, suitable for use in applications such as bridge and building construction, energy, industrial manufacturing, road plate and more.
Aside from both being widely-used grades, A572 and A36 differ greatly in their strength, machinability and composition. These differences could influence a buyer's decision on which material to use in their project. This article will explore those similarities and differences.
A36 & A572 Material Specifications
Grades
The A572 steel plate specification has five different grades: Grade 42, Grade 50, Grade 55, Grade 60 and Grade 65. Each of these grades have slightly different chemical compositions and mechanical properties. The A36 steel plate specification, on the other hand, does not cover multiple grades.
Chemical Composition
A36 steel plate is considered a low carbon, or mild, steel, meaning it contains a carbon composition of between 0.05% to 0.25%. The low carbon content of A36 plate makes it one of the most ductile - or machinable - types of carbon steel, meaning it is easy to form and machine into a variety of structural shapes.
A572 is also a mild carbon steel, but the greater addition of certain chemical alloys - such asphosphorus, manganese and silicon - makes it a high-strength, low-alloy (HSLA) steel, meaning it has higher strength and lower weight relative to mild steel. These properties make A572 plate ideal for use in structural applications that require the ability to withstand high stress, such as bridges and transmission towers.
Related: Exploring Mild & HSLA Steel
Chemical Composition of ASTM A36 Steel
| Chemical Alloy |
Up to ¾" Thick |
Over ¾" to 1 1/2" Thick |
Over 1 1/2" to 2 1/2" Thick |
Over 2 1/2" to 4" Thick |
Over 4" Thick |
| Carbon Max |
0.25% |
0.25% |
0.26% |
0.27% |
0.29% |
| Manganese |
N/A |
0.80-1.20% |
0.80-1.20% |
0.85-1.20% |
0.85-1.20% |
| Phosphorus Max |
0.030% |
0.030% |
0.030% |
0.030% |
0.030% |
| Sulfur Max |
0.030% |
0.030% |
0.030% |
0.030% |
0.030% |
| Silicon |
0.40% MAX |
0.40% MAX |
0.15-0.40% |
0.15-0.40% |
0.15-0.40% |
| Copper Min |
0.20% |
0.20 % |
0.20% |
0.20% |
0.20% |
Chemical Composition of ASTM A572 Steel
| Chemical Alloy |
Grade 42 |
Grade 50 |
Grade 55 |
Grade 60 |
Grade 65 ≥ 1/2" Thick |
Grade 65 Over 1/2" to 1 ¼" Thick |
| Carbon Max |
0.21% |
0.23% |
0.25% |
0.26% |
0.26% |
0.23% |
| Manganese Max |
1.35% |
1.35% |
1.35% |
1.35% |
1.35% |
1.65% |
| Phosphorus Max |
0.030% |
0.030% |
0.030% |
0.030% |
0.030% |
0.030% |
| Sulfur Max |
0.030% |
0.030% |
0.030% |
0.030% |
0.030% |
0.030% |
| Silicon |
0.15-0.40% |
0.15-0.40% |
0.15-0.40% |
0.40% |
0.40% |
0.40% |
Mechanical Properties
Due to differences in the chemical compositions of A36 and A572 steel, these materials differ in their mechanical properties, including yield point, which measures the point at which a material permanently changes shape after experiencing great forces, and tensile strength, which measures the force needed to cause material breakage or failure.
The higher presence of strengthening alloys, such as manganese and silicon, in A572 plate grades give the material greater strength as compared to A36. This higher strength allows A572 steel to bear more weight and withstand greater forces without breaking or failing, which is crucial in structural applications.
Mechanical Properties of ASTM A36 & ASTM A572 Steel Plate
| Grade |
Yield Point |
Tensile Strength |
| A36 |
36 ksi |
58-80 ksi |
| A572 Grade 42 |
42 ksi |
60 ksi |
| A572 Grade 50 |
50 ksi |
65 ksi |
| A572 Grade 55 |
55 ksi |
70 ksi |
| A572 Grade 60 |
60 ksi |
75 ksi |
| A572 Grade 65 |
65 ksi |
80 ksi |
Material Testing A36 & A572 Steel Plate
When used in colder environments, structural project engineers may request a Charpy impact test be performed on A572 and A36 materials. Charpy tests measure the ability of a material to withstand great forces within specific temperature ranges, which is crucial to ensure structural materials do not break or fail in harsh climates. Due to the additional strengthening alloys present in A572 steel, this material may be more suitable for colder climates than A36 steel.
For heavy A36 and A572 steel plate - which are plate materials greater than three inches thick - an ultrasonic test (UT) may be requested. UTs use a probe to send soundwaves into a material, which bounce back when detecting a flaw, making it useful on thicker materials where internal flaws may be hard to detect.
Are A36 & A572 Interchangeable?
Both A36 and A572 plate are primarily used in structural applications, which includes bridge and building construction, but they are not interchangeable. As discussed, A572 steel has greater strength and wear resistance than A36 steel, so it may be more suitable for use in heavy weight-bearing applications, such as use in constructing transmission towers or structural pieces enduring great forces.
Related: Exploring Structural Steel
A36 & A572 Cost Difference
As mentioned earlier, A36 is steel that has a minimum yield strength of 36,000 PSI. This grade derives its strength from a combination of carbon and manganese. On the other hand, A572-50, for example, is a type of steel with a minimum yield strength of 50,000 PSI. Similar to A36, it utilizes carbon and manganese for strength, but it also includes additional alloys such as columbium or vanadium. These extra alloys boost its overall strength, making A572-50 typically priced at around 2.5% - 5% higher than A36.
Related: How Much Does Steel Plate Cost?
Sourcing A36 & A572 Steel Plate For Structural Applications
When considering a source for A36 or A572 steel plate, it is important to considering the following factors in a supplier:
- Flexibility in buying options, such as the option to buy online or via a sales representative, to ensure you can source A36 and A572 plate in a way that best suits your needs
- Detailed paperwork to ensure the plate material you are procuring meets necessary specifications
- An ample stock of A36 and A572 plate to ensure you are able to source the grades and sizes you need
Leeco Steel has 11 strategically-located distribution centers across North America that are readily-stocked with various grades and sizes of A36 and A572 steel plate. Leeco also allows current customers to place A36 and A572 plate orders via its ecommerce website, Leeco Pro, providing greater flexibility and customization in the procurement process.
Request a quote for A36 or A572 steel plate today, or learn more about Leeco Pro.
