What are the grades of carbon steel?
Type | Carbon content | Typical grades | Core Features | Applicable scenarios |
Low carbon steel plate | ≤0.25% | Q195/Q215/Q235 | High plasticity, easy welding, low cost | Stamping parts (car doors/home appliance housings) |
Medium Carbon Steel Plate | 0.25%-0.6% | Q255/Q275/45# | Balanced strength and toughness, excellent wear resistance | Gears/Shafts/Mechanical Structural Parts |
High carbon steel plate | ≥0.6% | T8/T10/65Mn | Ultra-high hardness and strong fatigue resistance | Tools/Springs/Bearings |
Analysis of key selection parameters
1. Material and strength matching
- Construction field : Q235B (yield strength 235 MPa) is used for steel structure frames, Q345D (yield strength 345 MPa) is used for bridge load-bearing beams
- Automobile manufacturing : SPFH590 (tensile strength ≥590 MPa) is used for body reinforcements, taking into account both lightweight and collision safety
- Machining : 45# medium carbon steel has a hardness of HRC 40-50 after quenching and tempering, suitable for gears and drive shafts
2. Thickness and size adaptation
- Thin plate (0.5-4mm) : Q195 cold-rolled plate is used for electronic component housings, and the surface is galvanized to enhance corrosion resistance
- Medium and thick plate (4-20mm) : Q235 hot-rolled plate is used for building steel beams, which are directly welded after cutting
- Extra thick plate (≥20mm) : Q355NE is used for ship keels, and UT flaw detection is required to ensure that there are no internal defects
Application scenarios | Recommended brand | Performance requirements | Reference standards |
Building steel structure | Q345B | Excellent weldability, -20℃ impact energy ≥34J | GB/T 1591 |
car chassis | SAPH440 | High formability, tensile strength ≥440 MPa | JIS G 3135 |
shipbuilding | AH36 | Seawater corrosion resistance, Z-direction performance meets standards | ABS Classification Society Rules |
pressure vessel | Q245R | High temperature strength and non-destructive testing qualified | GB 713-2014 |
What is the ASTM standard for carbon steel?
Carbon structural steel comparison
China(GB) | USA(ASTM) | Japan(JIS) | Germany(DIN) | International standards(ISO) | Carbon content range |
Q235B | A36 | SS400 | S235JRG2 | E235B | ≤0.22% |
Q345D | A572 Gr50 | SM490YB | S355J2G3 | E355 | 0.18-0.24% |
20# | 1020 | S20C | C22 | C22E | 0.17-0.23% |
45# | 1045 | S45C | C45 | C45E4 | 0.42-0.50% |
Tool Steels vs. Special Purpose Steels
China(GB) | USA(ASTM) | Japan(JIS) | Germany(DIN) | Typical applications |
T8 | W1-8 | SK5 | C80W2 | Cutting Tools/Dies |
T10A | W1-1095 | SK3 | C105W1 | High precision measuring tools |
65Mn | 1566 | SUP6 | 65MnCr4 | Spring/Bearing |
Q295GNH | A588 | SPA-H | 09CuPCrNi-A | Weathering steel structure |
