The Key difference between A709 GR 50 and A572 GR 50 Corten Steel Sheet

ASTM A572 Grade 50 is one of the classifications that fall under the ASTM A572 standard, which is specifically designed for high-strength, low-alloy (HSLA) structural steel.

This grade is characterized by having a minimum yield strength of 50 kilopounds per square inch (ksi), which is approximately equal to 345 megapascals (MPa), indicating a high tolerance to stress before deformation.

ASTM A709 Grade 50 is a specific grade also defined in the ASTM A709 standard. This standard, which is known as the "Standard Specification for Structural Steel for Bridges", specifies the types of steel that are ideal for bridge construction, such as High-Strength Low-Alloy (HSLA) steel and carbon steel.

Grade 50 is categorized as HSLA steel, meaning it has a minimum yield strength of 50 kilopounds per square inch (ksi) or 345 megapascals (MPa), the same as A572 Grade 50.

1. Application

ASTM A572 Grade 50:

ASTM A572 Grade 50 is a globally known steel specification used in various general structural applications. This steel is usually utilized in the construction of buildings, equipment, and transmission towers. It is also suitable for use as a secondary component of bridges, indicating an important role in diverse construction projects.

ASTM A709 Grade 50:

ASTM A709 Grade 50 is specifically designed for bridge construction. This steel grade was formulated to satisfy the need for bridges to withstand the various stresses, loads, and demanding environmental conditions.

2. Mechanical Properties

ASTM A572 Grade 50

ASTM A572 Gr. 50 is engineered for strength and reliability. It boasts a minimum yield strength of 50 ksi (345 MPa) and a minimum tensile strength of 65 ksi (450 MPa).

Depending on the form and thickness, elongation values can range between 18% and 21% over a 2-inch stretch. This signifies a good balance between strength and flexibility.

ASTM A709 Grade 50

ASTM A709 Grade 50 provides significant advantages, particularly in bridge construction. Its tensile strength, yield strength, and elongation values are the same as A572 Grade 50.

The difference between the two is that A709 often imposes stricter requirements. This strictness is to ensure that it performs ideally in critical, heavy-duty applications like bridge loading.

3. Corrosion Resistance

ASTM A572 Grade 50

ASTM A572 Grade 50 offers good resistance to atmospheric corrosion due to its low-alloy composition. The composition, which is better than that of standard carbon steel, includes elements like columbium and vanadium that enhance its corrosion resistance.

It is important to remember that ASTM A572 Grade 50 is not classified as "weathering steel," unlike some grades mentioned in A709. As a result, ASTM A572 Grade 50 generally requires protective measures like painting or other coatings, especially in harsh environments where prolonged exposure to the elements cannot be avoided.

ASTM A709 Grade 50

ASTM A709 Grade 50 is also widely known for its strength and its ability to withstand various harsh environmental conditions. Unlike A572, it includes "Weathering Steel" options, such as A709 Grade 50W.

This grade is enhanced with elements such as copper, chromium, and nickel to help the steel develop a durable, rust-like patina that reduces corrosion.

With proper design and use, structures made from Grade 50W do not require painting most of the time, which leads to significant maintenance savings.

4. Certification and Testing

ASTM A572 Grade 50

ASTM A572 Grade 50 requires a mill certification to verify its compliance with the chemical and mechanical property standards stated in the ASTM A572 specification. The standard testing includes the measurement of tensile, yield strength, and elongation. A chemical analysis of the heat is also conducted as an additional test and then the result is reported.

Charpy V-notch (CVN) impact testing can be requested as a supplementary requirement by the purchaser, even if it is not mandatory. In CVN testing, the testing parameters, such as temperature and energy absorption levels, must be mutually agreed upon by both the buyer and the seller.

ASTM A709 Grade 50

ASTM A709 Grade 50 steel for bridge projects requires a dual certification. The certification must cover both the ASTM A709 standard and the AASHTO M270 specification because AASHTO establishes standards to ensure the safety and reliability of our highway and transportation infrastructure.

The certification process involves tests for yield strength, tensile strength, and elongation, as well as a comprehensive chemical analysis like that in A572. Charpy V-notch impact testing is mandatory for this steel grade.

Testing requirements will vary based on the climate zone where the bridge is located, and these zones are either Zone 1, Zone 2, or Zone 3. If a part is considered a fracture-critical member where failure could lead to serious issues, testing requirements become stricter and are done on a plate-by-plate basis.

5. Cost

ASTM A572 Grade 50

ASTM A572 Grade 50 is more affordable than the standard A709 Grade 50. This is all due to its less stringent mandatory testing requirements and simplified certification processes. This grade of steel is mass-produced, making it suitable for a wider range of applications.

The price for ASTM A572 Grade 50 plates generally ranges approximately between $410 to $810 USD per ton. If you are going to purchase in smaller quantities from metal suppliers, prices will skyrocket, often reaching between $6 – $8 USD per pound for cut pieces.

ASTM A709 Grade 50

ASTM A709 Grade 50 has higher costs due to several factors, such as the mandatory Charpy V-notch impact testing, stricter quality control measures, and stringent certification processes that often mandate adherence to AASHTO M270.

In terms of price, ASTM A709 Grade 50 plates vary significantly, usually ranging between $610 to $1,650 USD per ton or even more. This fluctuation in price is influenced by the grade of the steel, especially for weathering steel.

6. Availability

ASTM A572 Grade 50

ASTM A572 Gr. 50 is a widely used steel grade with high strength low alloy level. It is usually available in steel mills, distributors, and service centers in both industrialized and developing countries.

This steel grade comes in various forms such as plates and structural shapes, which include beams, columns, channels, angles, and bars.

Because of these characteristics, the steel has extensive applications in fields like construction, manufacturing, and infrastructure, which is why many steel suppliers keep A572 Grade 50 a part of their standard inventory.

ASTM A709 Grade 50

ASTM A709 Gr. 50 is primarily used in bridge construction. It is common in areas with significant infrastructure development, like North America, where both ASTM and AASHTO standards are critical. This grade of steel is normally available in plate form because that is the preferred material for bridge construction.

A709 Grade 50 is a special type of steel that is not mass-produced. If you want to procure this type of steel, it is advisable to contact steel suppliers that specialize in construction materials for infrastructure projects or have experience serving bridge fabricators.

In conclusion, ASTM A572 Grade 50 and ASTM A709 Grade 50 are both categorized as high-strength steels and have the same mechanical properties. Their difference lies in the fact that they are designed for different applications.

ASTM A572 Gr. 50, which is known for its versatility and cost-effectiveness, is an excellent choice for general structural applications, while ASTM A709 Gr. 50 is specifically engineered for bridge construction to provide enhanced toughness and corrosion resistance.

This grade also experiences more stringent certification and testing requirements, which affect its price. The selection between the two types of steel grades should always be based on the specific needs of the project, not what we personally prefer.

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What is A709 grade 50W steel?

ASTM A709-50W is a standard specification for structural steel primarily in the fabrication of steel bridges. ASTM A709-50W covers high strength, low allow steel structural shapes, plates and bars.

What is ASTM A709 steel grade?

The ASTM A709 is the Standard Specification for Structural Steel for Bridges and encompasses carbon, high-strength low-alloy, and quenched and tempered alloy steels used as structural plates in the construction of bridges. SSAB offers the following five grades of A709; 36, 50, 50W, HPS 50W and HPS 70W.

What is the difference between ASTM A572 Grade 50 and ASTM A709 Grade 50?

A572 Grade 50: Used in a wide range of structural applications, including buildings, transmission towers, equipment, and general construction. It's not specifically optimized for bridges. A709 Grade 50: Primarily used for bridge construction and other structures where enhanced toughness and weldability are critical.

What is the yield strength of ASTM A709 grade 50?

Grade 50 steel of this specification requires a minimum yield strength of 50 ksi. Used as structural members in bridge building or for similar structures.

What is the difference between ASTM A36 and A709?

ASTM A709 grade 36 is a bridge material wherein carbon adds to the strength and hardenability of the steel. A36 has less than0. 30% carbon and thus, do not possess high hardenability. ASTM A709 grade 36 steel plate has improved corrosion resistance and can be used in outdoor applications.

What is ASTM A572 grade 50 equivalent to?

ASTM A572 Grade 50 is equivalent to several other steel grades, with the most common international equivalents being S355JR (European standard) and Q345B (Chinese standard). The best equivalent depends on the specific project requirements, so it is always best to consult material specifications and a specialist to confirm compatibility.

What is the difference between ASTM A36 and ASTM A572 GR 50?

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.

What is the difference between A572 and s355?

In summary, both ASTM A572 Grade 50 and S355JR are excellent choices for structural steel applications, with ASTM A572 Grade 50 providing higher strength capabilities and S355JR offering versatility and widespread use in European construction projects.

Is A572 steel corrosion resistant?

A572 steel is typically used in structural applications due to its high strength, ductility, weldability and corrosion resistance. These applications include structural sections, reinforcing bars, bridges, skyscrapers and houses.