When it comes to structural steel for large-scale projects, infrastructure, and heavy fabrication, you’ll often come across two major grades: A36 and A572. Outwardly, the two grades serve similar purposes, so it’s only natural for the untrained eye to believe they’re identical. However, when weighing A36 vs A572 closely, they differ quite a lot in their strengths and capabilities.
Picking the wrong material might lead to overspending or, in some cases, risk the whole infrastructure. In this blog, we’ll walk you through the practical differences between A36 and A572 steel types to guide your decisions.
You can also check our related guides that compare A36 vs A1011, A36 vs A1018, or A36 vs A500.
What Are A36 and A572 Steel?
Before moving on to the head-to-head comparison of A36 vs A572, it’s important to understand the basics of these prime steel materials. Stats reveal that the global steel production for the construction industry is set to hit USD 1800.0 billion by 2032. This underscores the need to explore which steel best serves your large-scale project. Let’s break it down:
What is A36 Steel?
Made up of low-carbon steel, A36 steel is one of the most common steel grades in the US, primarily due to its high ductility. In other words, A36 steel can stretch considerably before fracturing, thanks to its yield strength of 36,000 psi. This makes it the go-to steel for general construction projects and various engineering projects. Plus, it’s composed of chemical alloys like Manganese, Phosphorus, and Vanadium that add to its machinability.
What is A572 Steel?
Next up, the A572 steel is known for its high-strength low-alloy (HSLA) properties and is made up of multiple grades, i.e., (42, 50, 55, 60, 65). It consists of a combination of alloys, including Columbium and Vanadium, which makes it ideal for heavy-duty applications. With a superior strength-to-weight ratio, A572 steel is designed for projects that demand more strength without adding to the weight. This makes it perfect for building columns, I-beams, and other weight-bearing applications.
A36 vs A572: Mechanical Properties Comparison
With the way A36 and A572 steel types are made, it’s safe to assume they possess distinct mechanical properties that make them fit for specific applications. For instance, A36 is ideal for everyday construction needs due to its welding-friendly nature. However, the composition of A572 makes it perfect for heavy-duty structures.
Here’s a closer look at the basic mechanical properties of these two steel types and how they differ from one another:
Mechanic Property | A36 Steel | A572 Steel |
Yield Strength | Minimum 36,000 PSI | Minimum 42,000 PSI |
Tensile Strength | 58-80 Ksi | Minimum 65 Ksi |
Ductility | Around 20-23% in 8″ | Around 18-21% in 8″ |
Modulus of Elasticity | Approx. 29,000 ksi | Approx. 29,000 ksi |
Chemical Composition Comparison
In addition to varying mechanical properties, another way to look at A36 vs A572 is to understand what they’re made of.
For example, A36 plate falls into the mild, low-carbon category, with around 0.3% carbon content by weight. A572, on the other hand, typically has 0.21% to 0.23% of carbon content. Here’s how the basic chemical composition differs:
Chemical Alloy | ASTM A36 | ASTM A572 (Grade 50) |
Carbon (C) | 0.3% | 0.21% – 0.23 % |
Manganese (Mn) | 0.8% – 1.2% | 0.4% – 1.35% |
Phosphorus (P) | ≤ 0.03% | ≤ 0.03% |
Sulfur Max (S) | ≤ 0.05% | ≤ 0.05% |
Silicon (Si) | 0.15% – 0.40% | 0.40% |
Copper (Cu) | 0.20% | 0.20% |
ASTM A572 vs A36: Workability and Fabrication Differences
Now that we have seen how the mechanical and chemical properties of A572 grade 50 vs A36 vary, it’s time to explore their workability and fabrication in the construction industry. Although both steels are easy to work with, they’re far apart from one another, too.
For instance, A36 steel has lower strength for easy cutting and welding, whereas A572 is a higher-strength steel with enhanced durability. To make it simpler, here’s what the basic fabrication differences look like:
ASTM A36
- Workability: Highly workable due to low carbon content, making cutting, welding, and milling easy.
- Fabrication: Ideal for general, light fabrication.
- Machining: Good machinability, which simplifies drilling and milling operations.
ASTM A572
- Workability: Due to higher strength and low thermal conductivity, it requires preheating before welding operations.
- Fabrication: Lower welding capability due to high strength.
- Machining: The increased strength makes machining slightly difficult and increases production times.
Can A572 GR 50 Replace A36?
When digging through the subject of A36 vs A572 steel, it’s only natural to wonder if the higher-strength A572 GR 50 will replace the A36. Well, yes and no. Yes, because A572-50 offers higher strength and desirable mechanical properties for most structural applications. However, the two steels aren’t directly interchangeable due to different chemical compositions.
Nonetheless, engineers often substitute A36 with A572 (grade 50) for beams, columns, and bridges for lighter yet more durable designs. For general construction or small-scale fabrication, A36 still remains the top choice, especially for its cost-effectiveness and simpler welding. As such, it’s best to always check the project specifications before making any such substitutions.
Cost, Material Efficiency, and Availability
When deciding between A36 vs A572 steel for practical applications, the two most critical factors include the cost and the supply. Understandably, A36 is cheaper since it has a simpler makeup and is widely available. However, if you’re thinking long-term, A572 can be more pocket-friendly due to added strength and durability, which reduces the need for constant repairs.
Here’s a general cost and supply overview to make your decision of A36 vs A572 simpler:
Factor | A36 | A572 |
Cost | Generally more affordable | Slightly more expensive |
Material Efficiency | Cost-friendly option for applications that don’t require high strength | More material-efficient due to higher strength, light components |
Availability | Widely produced and available | Grade 50 widely available |
A572 Grade Variants: When to Use 50, 60, or 65?
As mentioned earlier, ASTM A572 is widely used for a vast variety of structural applications, particularly those that require higher strength. Plus, it’s available in multiple grades, with grade 50 being the most common. Unless your project has extreme strength requirements, Grade 50 will cover most of the needs.
However, it’s natural to wonder when to use other Grades like 50, 60, and 65. Here’s a tabular breakdown of common A572 variants and when to use them for structural and fabrication purposes:
A572 Grade Variant | Yield Strength | Typical Structural Application |
50 (most common) | 50 ksi | Construction of Bridges, building frames, machinery components, transmission towers, basic building applications |
60 | 60 ksi | Heavy construction equipment, heavy machinery, I-beams, marine construction projects |
65 | 65 ksi | Specialized applications using maximum strength, load-bearing frameworks, truck frames, other heavy machinery components |
FAQs
Is it possible to weld A572 to A36?
Although A36 has a higher weldability than A572, it’s entirely possible to weld ASTM A572 to A36 since both of these steels are low-carbon. However, it’s critical to consult the AWS welding code to initiate the process.
Can A36 and A572 be used together in the same structure?
Yes, it’s possible to use both A36 and A572 steel types in the same project, but the design should consider their strength and welding differences. Yet, it’s advisable to seek guidance from AWS D1.1 standards.
A36 vs A572: which steel grade is more expensive?
Typically, ASTM A572 is more expensive than A36, primarily due to its incredibly high strength. It consists of alloys like Vanadium that enhance its strength, which in turn scales up the production costs.
Conclusion
Choosing between A36 vs A572 might be tricky, especially if you’re new to the industry with limited knowledge of steel components. For applications that require just sufficient strength, A36 is a pretty cost-friendly option to consider. It’s easy to work with, has high weldability, and has lesser turnaround times.
However, if you’re aiming for large-scale production with higher strength, A572 (especially grade 50) is your best bet. All things said, it’s best to know your project requirements first to guide your steel choice. Contact Zhaojian steel to know more about which steel type and grade best serve you!
