Products Description
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.
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 as phosphorus, 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.
Chemical Composition of ASTM A36 Steel
|
Chemical Alloy |
Up to ¾" Thick |
Over ¾" to 1 ½" Thick |
Over 1 ½" to 2 ½" Thick |
Over 2 ½" 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 ≥ ½" Thick |
Grade 65 Over ½" 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 |
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.