Q345 Steel: Q345A, Q345B, Q345C, Q345D & Q345E
Q345 steel is a Chinese standard low alloy high strength structural steel. The material has a minimum yield strength of 345 MPa (50 ksi), and tensile strength of 470-630 Mpa (68-91 ksi). It has better properties than Q235. According to GB/T 1591 – 2008, Q345 material has 5 quality grades: Q345A, Q345B, Q345C, Q345D and Q345E.
Meaning & Designation
- “Q” is short for Pinyin: “Qu”, which means Yield strength;
- “345” indicates the steel has a minimum value of yield strength 345 MPa for steel diameter/thickness ≤16mm.
- A, B, C, D and E indicate the quality grade.
Properties, Datasheet and Specification
Q345, Q345A, Q345B, Q345C, Q345D and Q345E steel properties, datasheet and specification are listed in the tables below, including chemical composition, physical and machenical properties, etc.
Chemical Composition
Chemical Composition Based on melting analysis.
| | | Chemical Composition (≤%) |
| Steel Grade | Quality Grade | C | Si | Mn | P | S | Cr | Ni | Mo | Cu | Ti | N | Nb | V | B | Al, ≥ |
| Q345 | Q345A | 0.20 | 0.50 | 1.70 | 0.035 | 0.035 | 0.30 | 0.50 | 0.10 | 0.30 | 0.20 | 0.012 | 0.07 | 0.15 | – | – |
| Q345B | 0.035 | 0.035 |
| Q345C | 0.030 | 0.030 | 0.015 |
| Q345D | 0.18 | 0.030 | 0.025 |
| Q345E | 0.025 | 0.020 |
Notes: The P and S contents of profiles and bars can be increased by 0.005%, and the upper limit of Grade A steel can be 0.0045%.
Q345 Material Mechanical Properties
Q345 material mechanical properties are listed in the table below, including yield strength, tensile strength and elongation.
| | | Yield Strength, MPa (ksi), ≥ |
| Steel Grade | Quality Grade | t ≤16 | 16< t ≤ 40 | 40 <t ≤ 63 | 63 <t≤ 80 | 80 < t ≤ 100 | 100 < t ≤ 150 | 150 < t ≤ 200 | 200 < t ≤ 250 | 250 < t ≤ 400 |
| Q345 | Q345A | 345 (50) | 335 (49) | 325 (47) | 315 (46) | 305 (44) | 285 (41) | 275 (40) | 265 (38) | – |
| Q345B |
| Q345C |
| Q345D | 265 (38) |
| Q345E |
Notes:
- t= Thickness or diameter (mm);
- 1 MPa = 1 N/mm2
| | | Tensile Strength, MPa (ksi) |
| Grade | Quality Grade | t≤ 100 | 100< t ≤250 | 250< t ≤400 |
| Q345 | Q345A | 470-630 (68-91) | 450-600 (65-87) | – |
| Q345B |
| Q345C |
| Q345D | 450-600 (65-87) |
| Q345E |
| | | Elongation (%, ≥) |
| Grade | Quality Grade | t≤40 | 40 <t ≤ 63 | 63 < t≤ 100 | 100 <t≤ 150 | 150 < t ≤ 250 | 250 <t ≤ 400 |
| Q345 | Q345A | 20 | 19 | 19 | 18 | 17 | – |
| Q345B |
| Q345C | 21 | 20 | 20 | 19 | 18 |
| Q345D | 17 |
| Q345E |
Charpy Impact
Charpy (V-notch) impact test temperature and impact absorption energy (KV2/J).
| Quality | Temperature, °C (°F) | 12≤t≤150 (mm) | 150<t≤250 (mm) | 250<t≤400 (mm) |
| Q345B | 20 (68) | ≥34J | ≥27J | – |
| Q345C | 0 (32) |
| Q345D | -20 (-4) | 27J |
| Q345E | -40 (-40) |
Physical Properties
Density: 7.85 g/cm3 (0.284 lb/in3)
Melting point: 1450-1530 °C (2640-2800 °F)
Applications
Q345 steel has high strength, excellent weldability, cold & hot workability and certain corrosion resistance. It is widely used in bridges, ships, boilers, pressure vessels, petroleum storage tanks, lifting transport machinery and other high-load welded structural parts.
Q345 Steel Equivalent
Q345 steel: Q345A, Q345B, Q345C, Q345D, Q345E equivalent ASTM, European, German, British, France, Australian, Canadian, Japanese and Indian Standard (For Reference).
Notes: Q345 steel has been replaced by Q355 in the latest version of GB standard “GB/T 1591 – 2018”, the previous version is “GB/T 1591 – 2008”.
| Low Alloy Structural Steel Q345 Equivalent |
| Chinese | US | European | Australian | Canadian | Indian | Japanese | ISO |
| Standard | Grade | Standard | Standard | Grade (steel number) | Standard | Grade | Standard | Grade: Imperial (SI) | Standard | Grade | Standard | Grade | Standard | Grade |
| GB/T 1591 – 2008 | Q345A | ASTM A529 Grade 50 [345] ;
ASTM A572 Grade 50 [345];
ASTM A588;
ASTM A678 Grade A | | | | | | | | | | | | |
| GBT 1591 – 2008 | Q345B | EN 10025-2;
DIN 17100 | S355, S355JR (1.0045),
E355 (1.0060);
St52-3 | AS/NZS 3678 | 350 | CSA G40.20/G40.21 | 50W (350W) | IS 2062 | E350 | JIS G3135 | SPFC 590 | ISO 630-2 | S355C, S355D (S355) |
| GB1591 – 2008 | Q345C | EN 10025-2;
DIN 17100 | S355J0 (1.0553),
E335 (1.0060);
St52-3 | AS/NZS 3678 | 350L0 | CSA G40.20/G40.21 | 50W(350W) | IS2062 | E 350 | JIS G 3135 | SPFC590 | ISO 630-2 | S355D |
| GB 1591 – 2008 | Q345D | ASTM A656 Grade 50 [345];
ASTM A529 Grade 50 [345] | EN 10025-2;
EN 10025: 1993;
DIN 17100 | S355J0 (1.0553),
E335 (1.0060);
S355J2G3 (1.0570);
St52-3 | AS/NZS 3678 | 350L20 | CSA G40.20/G40.21 | 50W (350W) | IS 2062 | E350 | JIS G 3135 | SPFC590 | ISO630-2 | S355D |
| GBT 1591 – 2008 | Q345E | ASTM A656/A656M Grade 50 [345];
ASTM A529/A529M Grade 50 [345];
ASTM A808 | EN 10025-2;
EN 10025: 1993 | S355J2 (1.0553),
S355K2 (1.0596),
S355J2G4 (1.0577),
S355K2G3 (1.0595),
S355K2G4 (1.0596) | AS/NZS 3678 | 350L40 | CSA G40.20/G40.21 | 50W(350W) | | | JIS G31 |
