Q345 Steel Properties and Introduction
Q345 steel is a Chinese GB standard Low Alloy High Strength Structural Steel, material density is 7.85 g/cm3, tensile strength is 470-630 Mpa, and yield strength is 345 MPa. According to GB/T 1591 – 2008, Q345 material has 5 quality grades: Q345A, Q345B, Q345C, Q345D and Q345E.
Q345 steel has good weldability, cold & hot workability and corrosion resistance. Widely used in bridges, ships, boilers, pressure vessels, petroleum storage tanks, lifting transport machinery and other high-load welded structural parts.
Meaning & Designation
“Q” is the first letter of Chinese Pinyin: “qu fu dian”, which means Yield Point, “345” is the minimum value of yield strength 345 MPa for steel thickness ≤16mm.
Datasheet and Specification
For datasheet and specification, please see the tables below.
Table-1, Chemical Composition of Q345 Steel
| Chemical Composition Content (≤%) | ≥% | |||||||||||||||
| Steel Grade | Quality Grade | C | Si | Mn | P | S | Nb | V | Ti | Cr | Ni | Cu | N | Mo | B | Als |
| Q345 | Q345A | 0.20 | 0.50 | 1.70 | 0.035 | 0.035 | 0.07 | 0.15 | 0.20 | 0.30 | 0.50 | 0.30 | 0.012 | 0.10 | – | – |
| 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%.
Table-2, Q345 Mechanical Properties
| Mechanical Properties: Yield Strength (≥ N/mm2) | ||||||||||
| Steel Grade | Quality Grade | Ø ≤16 | 16 < Ø ≤ 40 | 40 < Ø ≤ 63 | 63 < Ø ≤ 80 | 80 < Ø ≤ 100 | 100 < Ø ≤ 150 | 150 < Ø ≤ 200 | 200 < Ø ≤ 250 | 250 < Ø ≤ 400 |
| Q345 | Q345A | ≥345 | ≥335 | ≥325 | ≥315 | ≥305 | ≥285 | ≥275 | ≥265 | – |
| Q345B | ||||||||||
| Q345C | ||||||||||
| Q345D | ≥265 | |||||||||
| Q345E | ||||||||||
Notes: Ø = Thickness or wire diameter in mm;
1 MPa = 1 N/mm2
| Mechanical Properties: Tensile Strength (N/mm2) | ||||||||
| Grade | Quality Level | Ø ≤ 40 | 40 < Ø ≤ 63 | 63 < Ø ≤ 80 | 80 < Ø ≤ 100 | 100 < Ø ≤ 150 | 150 < Ø ≤ 250 | 250 < Ø ≤ 400 |
| Q345 | Q345A | 470 – 630 | 470 – 630 | 470 – 630 | 470 – 630 | 450 – 600 | 450 – 600 | – |
| Q345B | ||||||||
| Q345C | ||||||||
| Q345D | 450 – 600 | |||||||
| Q345E | ||||||||
| Ø mm, Elongation (≥%) | |||||||
| Grade | Quality Level | Ø ≤40 | 40 < Ø ≤ 63 | 63 < Ø ≤ 100 | 100 < Ø ≤ 150 | 150 < Ø ≤ 250 | 250 < Ø ≤ 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), thickness (t).
| Quality | Temperature, ℃ | 12-150 (mm) | 150<t≤250 (mm) | 250<t≤400 (mm) |
| Q345B | 20 | ≥34J | ≥27J | – |
| Q345C | 0 | |||
| Q345D | -20 | 27J | ||
| Q345E | -40 |
Q345 Equivalent
Q345 steel: Q345A, Q345B, Q345C, Q345D, Q345E equivalent to US ASTM, European Germany DIN, British BS, France NF, Japan JIS, and ISO 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”.
| Q345 Equivalent | |||||||||||||
| China | USA | Germany | Japanese | ISO | |||||||||
| Standard | Grade | Standard | Grade | Standard | Grade (steel number) | Standard | Grade | Standard | Grade | ||||
| GB/T 1591 – 2008 (Year) | Q345A | ASTM A529/A529M; ASTM A572/A572M; ASTM A588/A588M; ASTM A678/A678M; ASTM A808/A808M | Grade 50; Grade 50; Grade B; Grade D; A808M | JIS G3135 | SPFC590 | ISO 630-2 | S355C, S355D (S355) | ||||||
| GB/T 1591 – 2008 | Q345B | Ditto | Ditto | DIN EN 10025-2; DIN 17100 | S355, S355JR (1.0045), E355 (1.0060); St52-3 | JIS G3135 | SPFC 590 | ISO 630-2 | S355C, S355D (S355) | ||||
| GB/T1591 – 2008 | Q345C | Ditto | Ditto | DIN EN 10025-2; DIN 17100 | S355J0 (1.0553), E335 (1.0060); St52-3 | JIS G 3135 | SPFC590 | ISO 630-2 | S355D (S355) | ||||
| GB/T 1591 – 2008 | Q345D | ASTM A656/A656M; ASTM A529/A529M | Type 7; Grade 50 | DIN EN 10025-2; DIN EN 10025: 1993; DIN 17100 | S355J0 (1.0553), E335 (1.0060); S355J2G3 (1.0570); St52-3 | JIS G 3135 | SPFC590 | ISO 630-2 | S355D (S355) | ||||
| GB/T 1591 – 2008 | Q345E | ASTM A656/A656M; ASTM A529/A529M | Type 7; Grade 50 | DIN EN 10025-2; DIN EN 10025: 1993 | S355J2 (1.0553), S355K2 (1.0596), E335 (1.0060); S355J2G4 (1.0577), S355K2G3 (1.0595), S355K2G4 (1.0596) | JIS G3135 | SPFC 590 | ||||||
Tags: Q345A steel, Q345B steel, Q345C steel, Q345D steel, Q345E steel
