Q355 steel is a low alloy, high-strength steel that is used in welded structures supporting stress and heavy loads. The Q references the yield point, while the number 355 indicates its yield strength. It also replaced Q345.
Characteristics of Q355
Q355 steel is a structural steel with a yield strength of 345 MPa and tensile strength of 450 MPa. It has terrific processing performance and compressive strength, which can be used to manufacture high-pressure gas pressure vessels containing less than 500 liters. Q355 also has a protective layer of rust resistance.
In addition to performance, Q355 has particular elements that prevent atmospheric corrosion. Since it is mild steel, it has a lower carbon content. If more carbon were added to the alloy, it would be reclassified as a cast iron.
Q355 is a newer Chinese steel grade that was designed to replace Q345. Its material density is 7.85 g/cm3 and possesses three quality levels, including Q355B, Q355C, and Q355D. It has great mechanical and hot and cold process properties. In contrast, it has better and more improved mechanical properties when compared to A36 ASTM steel.
Uses of Q355
Q355 steel has excellent mechanical properties, great weldability, and ample corrosion resistance. It can be utilized to manufacture and produce petroleum storage tanks, high-pressure vessels, boilers, ships, power stations, and many other high-load structural parts. Q355 is also widely used to make shipping containers, waste storage containers, weather containers, offshore containers, workshop containers, and toolboxes.
If you need steel that is created to stand up to the needs of construction and engineering components that provide excellent weldability and toughness, then Q355 may be a strong contender for your next project or job.
Q355 Physical Properties
| Physical Properties | Metric | US/Imperial |
| Density | 7.80 g/cc | 0.282 lb/in³ |
Q355 Mechanical Properties
| Mechanical Properties | Metric | US/Imperial |
| Hardness, Brinell | 135 | 135 |
| Hardness, Rockwell B | 74 | 74 |
| Tensile Strength, Ultimate | 450 MPa | – |
| Tensile Strength, Yield | 345 MPa | – |
| Elongation at Break | 18 % | 18 % |
| 21 % | 21 % | |
| Bulk Modulus | 160 GPa | 23200 ksi |
| Shear Modulus | 80.0 GPa | 11600 ksi |
Q355 Component Elements Properties
| Material | C | Si | Mn | P | S | Cr | Ni | Cu |
|---|---|---|---|---|---|---|---|---|
| Q355B | ≤0.20% | ≤0.55% | ≤1.60% | ≤0.035% | ≤0.035% | ≤0.30% | ≤0.30% | ≤0.40% |
| Q355C | ≤0.20% | ≤0.55% | ≤1.60% | ≤0.030% | ≤0.030% | ≤0.30% | ≤0.30% | ≤0.40% |
| Q355D | ≤0.20% | ≤0.55% | ≤1.60% | ≤0.025% | ≤0.025% | ≤0.30% | ≤0.30% | ≤0.40% |
| Q355E | ≤0.18% | ≤0.50% | ≤1.60% | ≤0.025% | ≤0.020% | ≤0.30% | ≤0.30% | ≤0.40% |
Element Functions
- Carbon (C): One of the main alloying elements in steel. Appropriate carbon content improves the strength and hardness of steel.
- Silicon (Si): A deoxidizer in steel that helps remove oxygen, sulfur, phosphorus, and other impurities, improving the purity and corrosion resistance of steel.
- Manganese (Mn): Improves the strength and hardness of steel, enhances its toughness and ductility, and also increases its wear resistance and corrosion resistance.
- Phosphorus (P) and Sulfur (S): Impurity elements in steel. Excessive content reduces the toughness and ductility of steel, easily causing brittle fracture, so their levels must be strictly controlled.
- Chromium (Cr): Improves the corrosion resistance and oxidation resistance of steel, and also enhances its wear resistance and high-temperature resistance.
- Nickel (Ni): Improves the toughness and ductility of steel, enhances fatigue strength, and also increases its corrosion resistance.
- Molybdenum (Mo): Improves the hardness, strength, and corrosion resistance of steel, and also enhances its quenching hardenability.
- Vanadium (V): Improves the strength and hardness of steel, and enhances its ductility and bending performance.
- Niobium (Nb) and Titanium (Ti): Commonly used alloying elements that improve the strength and toughness of steel while reducing its weight.
Q355 Equivalent Materials
Q355 can be replaced with equivalent materials, including A572 Grade 50 USA ASTM, Q355 China GB/T, and SM490/Japanese JIS.
ASTM A572 Gr 50: This is an equivalent grade to Q355 in the American ASTM standards. It has a minimum yield strength of 345 MPa and is commonly used in structural applications.
S355JR: This is an equivalent grade to Q355 in the European EN standards. It has a minimum yield strength of 355 MPa and is widely used in structural and engineering applications.
SM490B or SM490C: These are equivalent grades to Q355 in the Japanese JIS standards. They have minimum yield strengths of 325 MPa and 365 MPa, respectively, and are commonly used in structural applications.
Not all low alloy structural steel delivers consistent performance like Q355. Its balanced chemical makeup, outstanding strength and cross-standard equivalent alternatives make it the top choice for global buyers. Contact us to get matched Q355 grades and customized service for your project.
What is Q355 steel equivalent to?
A572 Grade 50
Q355 can be replaced with equivalent materials, including A572 Grade 50 USA ASTM, Q355 China GB/T, and SPFC 590 Vietnam/Japanese JIS.
What is the chemical composition of Q355 steel?
Chemical composition: C: ≤0.24, Si: ≤0.55, Mn: ≤1.60, P: ≤0.035, S: ≤0.035, Cr: ≤0.30, Ni: ≤0.30, Cu: ≤0.40. tensile strength: 450–630.
What is Chinese steel grade Q355?
Q355 steel is a Chinese structural steel grade that is part of the GB/T 1591 standard. It is a high-strength low-alloy steel known for its excellent mechanical properties, making it suitable for various structural applications in construction and engineering.
What is the ASTM equivalent of Q355B steel?
ASTM A572 Grade 50
The equivalent ASTM material for Q355B steel is ASTM A572 Grade 50. ASTM A572 Grade 50 is a structural steel with high strength and low alloy content that is widely utilized in structural applications.
What is the difference between S355 and q355?
Q355 and S355 are not identical standards, but they are functionally equivalent for most structural applications. Both have a minimum yield strength of 355 MPa and similar tensile strength ranges. The main differences lie in standard specifications, chemical composition limits, and delivery conditions.
What is Q355D equivalent to?
Q355D steel material is equivalent to S355J2 steel material in European specification EN 10025-2.
