S690Q vs A36: A Critical Comparison of High-Strength vs. General Structural Steel Plates

S690QL is a high-strength, quenched and tempered (Q&T) steel with a minimum yield strength of 690 MPa, while A36 is a standard-strength carbon structural steel with a minimum yield strength of 36,000 psi (approximately 250 MPa). The key difference is that S690QL is designed for high-load applications where high strength and reduced weight are critical, such as heavy engineering and offshore structures, whereas A36 is a more common and less expensive steel for general construction.

S690QL is a high-strength, quenched, and tempered structural steel that is designed for use in demanding applications, particularly in the construction and engineering sectors. It is part of the EN 10025-6:2004 standard and is characterized by excellent mechanical properties, including high yield strength and good weldability. Below are the detailed properties of S690QL steel:

Mechanical Properties

• Yield Strength: 690 MPa (min) This high yield strength makes S690QL suitable for applications that require strong and durable materials.
• Tensile Strength: 770 - 940 MPa The tensile strength is also high, allowing S690QL to resist breaking under tension.
• Elongation: 14% (min) for thicknesses up to 16 mm; this percentage decreases slightly with increased thickness Good elongation means the material can deform without breaking, which is important for safety and flexibility in certain applications.
• Impact Toughness:

Chemical Composition

S690QL is a low-alloy, high-strength steel, and its typical chemical composition includes:

• Carbon (C): 0.12 - 0.20%
• Manganese (Mn): 1.50 - 2.00%
• Silicon (Si): 0.50 - 0.80%
• Chromium (Cr): 0.50% max
• Nickel (Ni): 0.40% max
• Molybdenum (Mo): 0.20% max
• Vanadium (V): 0.05% max
• Phosphorus (P): 0.025% max
• Sulfur (S): 0.010% max

This combination of elements provides the steel with excellent hardenability, corrosion resistance, and weldability.

Applications

S690QL is widely used in industries that require materials with high strength-to-weight ratios, such as:

Construction: In the manufacturing of cranes, bridges, heavy machinery, and other structural components that need to withstand high loads.

Mining: For the production of mining equipment like excavators, bulldozers, and other heavy machinery.

Energy: Used in applications like wind turbine towers and offshore structures.

Shipbuilding: For creating strong yet lightweight hulls and other parts of ships.

Heat Treatment

S690QL steel is quenched and tempered, which means that it undergoes a heat treatment process that involves heating the steel to a high temperature and then cooling it rapidly (quenching), followed by tempering (reheating to a lower temperature and then cooling). This results in increased strength and toughness.

Quenching: The steel is heated to a specific temperature and then rapidly cooled, which increases the hardness of the material.

Tempering: The steel is then tempered to adjust the hardness and toughness, ensuring that the material is not too brittle for its intended use.

Weldability

S690QL steel is known for its good weldability. However, special precautions must be taken when welding due to its high strength. The welding process should use low-hydrogen electrodes, and the material should be preheated and post-weld heat treated to minimize the risk of cracking.

Advantages of S690QL Steel

High Strength: S690QL offers excellent strength, making it ideal for load-bearing applications.

Versatility: It can be used in a variety of industries due to its versatile properties.

Good Toughness: Despite its high strength, S690QL has excellent impact toughness at low temperatures.

Good Weldability: This material can be welded with proper care and precautions, making it suitable for construction and structural purposes.

What is A36 Grade steel?

A36 steel is a standard structural steel that can be welded, punched, drilled, tapped, or machined.

High value and versatile, A36 is widely used in various industries, from construction to automobile manufacturing. This steel plate is known for its high strength, formability, and weldability. It's also an excellent magnetic field conductor. Together, these benefits make A36 one of the most-used grades of carbon steel.

The American Society for Testing and Materials (ASTM) designated it A36. The "A' stands for ferrous material, and the "36" is added because the steel's yield strength is 36,000 PSI.

A36 Steel Composition

All steel is composed of iron and carbon, usually with a smattering of other elements added to the alloy. A steel grade's exact chemical composition helps determine its strength, elasticity, and weight-bearing capacity and plays a crucial role in its mechanical performance.

Like other steel grades, A36 steel contains primarily iron but also includes small amounts of other elements that give it specific mechanical properties.

The typical chemical composition includes:

Carbon (C): 0.25% (max)

Copper (Cu): 0.20% (min)

Iron (Fe): 98%

Manganese (Mn): 1.03%%

Phosphorus (P): 0.04% (max)

Sulfur (S): 0.05% (max)

Silicon (Si): 0.28% (max)

What does each of these chemicals contribute to A36 steel?

Carbon content directly affects steel's hardness and strength. A low-carbon steel, sometimes called "mild steel," like A36, is weaker than steel grades with a higher carbon content. While "weaker" doesn't sound like a positive adjective when talking about structural metals, it means that low-carbon steels are easier to weld, bend, punch, or machine - all qualities you want in a good construction material.

Manganese and silicon improve steel's toughness and wear resistance. They are both deoxidizers, which means they remove oxygen from a chemical process. You want that in steel because it helps prevent defects and decay.

Phosphorus and sulfur, present in small amounts in A36, are often considered impurities but are controlled to maintain steel's performance during manufacturing and usage. Phosphorus can make steel easier to weld, and sulfur makes it simpler to cut and shape.

Designation of ASTM A36

ASTM uses a particular logic in grading steel. While you might think of a high grade as "better" and a low grade as "worse," that isn't how the process works. The organization assigns a series of letters, numbers, and sometimes dashes, each of which indicates something about the metal itself. "Grades" are not like what you remember from school; they're just indicators.

"A" is for ferrous or iron-related material, so when you see a metal grade beginning with "A," you know it contains iron. You don't know how much carbon it contains, if it's stainless or an alloy - just that it's primarily iron. The rest of the designation is intended to help answer additional questions.

In this case, the ASTM A36 standard specifies the mechanical properties of A36 steel and its chemical composition. This designation ensures that the steel meets the necessary criteria for structural applications, providing a benchmark for manufacturers and engineers. ASTM A36 applies to various shapes and sizes, including steel plates, bars, and beams.

Is A36 Steel the Same as Mild Steel?

Yes, A36 steel is classified as a type of mild steel. Mild steel refers to carbon steels with a relatively low carbon content, usually between 0.05% and 0.25%. These steels are more affordable, more weldable, and more corrosion-resistant than carbon steels but also about 20% weaker. Since they are malleable and easier to work with, mild steels are often chosen over high-carbon steels.

A36 fits this classification due to its low carbon content of around 0.25%. However, it stands out from other mild steels due to its balanced mechanical properties, making it a top choice for structural applications that require flexibility and malleability.

What is an A36 Steel Equivalent?

A36 steel has equivalents in other countries and standards. For instance, Europe's closest equivalent is S235JRG2; in Japan, it's SS400. Canada uses the designation 260W, and India labels it E250. These grades share similar mechanical properties, though there may be slight variations based on regional standards.

For inquiries about S690Q high-strength structural steel, A36 general-purpose carbon steel, or custom steel solutions, contact GNEE Steel today:

Phone: +86 15824687445

Email: alloy@gneesteelgroup.com

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FAQ

What is the difference between S690Q and S690QL?

S690Q: Minimum impact toughness tested at -20°C (30J average). → Typical Use: Cranes in temperate climates, quarry equipment. S690QL: Certified for -40°C and below (≥40J impact toughness). → Critical Use: Arctic pipelines, offshore platforms, mining vehicles in Siberia.

What grade is S690QL material?

S690QL is a high strength quenched and tempered steel grade that complies to steel specification EN 10025. The designation S690QL refers to a minimum yield strength of 690 MPa.

What is S690 grade steel?

S690 high yield & fine grain steel plate is a high strength, quenched and tempered fine-grain structural steel. Structural steel S690 is used in structures that must withstand very heavy loads. This grade is meant for structures where weight savings is important.

What is the equivalent of S690 steel?

Approximate equivalents
ASTM A514, EN 10149-2 Grade S700MC, AS/NZS 3579 Grade 700, AM 700, Bisalloy 80.

What is the price of S690QL material?

S690QL High Strength Steel Plates, Thickness: 5mm to 150mm at 5,600-13,500 CNY per tonne (approx. 5.6-13.5 CNY per kilogram)/440-900 USD per tonne (approx. 0.44-0.90 USD per kilogram)

What is the hardness of S690 QL steel?

S690QL steel stockholders and suppliers. S690QL is a quenched and tempered high strength steel supplied in full plates or cut pieces with delivery to the whole of the UK. With its high yield of minimum 690MPa it offers better strength than standard carbon steel grades.

What is the effective use of high strength S690 steel in construction?

The high strength S690 steels have an excellent strength-to-self-weight ratio, and they are highly efficient to be used in heavily loaded structures. Typical applications include piles and columns in buildings and supporting members in bridges.

What is the difference between S890QL and S690QL?

S690QL, S890QL, and S960QL are all water quenched and tempered steels that comply with the EN10025:6:2004 specification. These ultra high strength steels have a minimum yield strength of 690 MPa, 890 MPa, and 960 Mpa respectively, making them ideal for use in the haulage sector.

What is the difference between S700MC and S690ql?

The S700MC Steel is basically a structural steel plate developed especially for applications requiring high yield strength. They are used for several load bearing applications. The S690ql is a low alloy structural steel which is high in strength and comes with good weldability.

What is the yield strength of s690 steel?

690 MPa.

Yield strength of 690 MPa. Used in structures bearing extremely heavy loads, such as bridges, offshore drilling rigs and buildings, as well as in heavy construction equipment and cranes.

What is A36 steel plate?

ASTM A36 Steel Plate is one of the most common grades of steel used in structural applications. This mild carbon steel grade contains chemical alloys that give it properties such as machinability, ductility, and strength that are ideal for use in constructing a variety of structures.

Is A36 the same as mild steel?

A36 Steel has a lower carbon content than Mild Steel. A36 Steel is more weldable than Mild Steel. A36 Steel is more machinable than Mild Steel. A36 Steel has a higher yield strength than Mild Steel.