Q235B Steel – Meaning and Designation
"Q": First letter of the Chinese pinyin "Qu" (屈), meaning Yield Point.
"235": Minimum yield strength of 235 MPa for steel bars or plate thickness ≤16 mm.
Quality Grades: A, B, C, D – with Q235B representing the most commonly used grade with stable quality, good toughness, and weldability.
Features and Applications
Q235B steel is a low-carbon structural steel notable for:
Good plasticity and toughness
Excellent weldability
Balanced strength and cold bending ability
Common Forms:
Wire rods, round bars, square bars, flat bars
Angle beams, I-beams, channel beams
Steel plates and tubes/pipes
Typical Applications:
Construction & Engineering: Welded structures, industrial buildings, bridges, transmission towers
Vehicles & Machinery: Boilers, containers, lightly stressed mechanical parts (rods, brackets, supports, screws, nuts, ferrules)
General Fabrication: Structural and mechanical components requiring moderate strength
Q235B Chemical Composition (Mass Fraction, %) by Heat Analysis
| Steel Grade | Quality | C (%) | Si (%) | Mn (%) | P (%) | S (%) | Deoxidation Method |
|---|---|---|---|---|---|---|---|
| Q235 | Q235A | 0.22 | 0.35 | 1.40 | 0.045 | 0.050 | Rimmed / Killed |
| Q235 | Q235B | 0.20 | 0.35 | 1.40 | 0.045 | 0.045 | Rimmed / Killed |
| Q235 | Q235C | 0.17 | 0.35 | 1.40 | 0.040 | 0.040 | Killed |
| Q235 | Q235D | 0.17 | 0.35 | 1.40 | 0.035 | 0.035 | Exceptionally Killed |
Q235B Equivalent Steel Standards Worldwide
| Chinese GB/T 700 | US ASTM | EU EN | UK BS | Australia AS/NZS | Japan JIS | India IS |
|---|---|---|---|---|---|---|
| Q235B | ASTM A36; ASTM A283/A283M: A36, Grade D | EN 10025-2: S235JR (1.0038) | BS EN 10025-2: S235JR (1.0038) | AS/NZS 3678: 250 | JIS G3101/G3106: SS400, SM400A | IS 2062: E250B |
Q235B is widely used in steel pipes, tubes, and structural components due to its high toughness, weldability, and moderate strength. Its chemical composition ensures reliable performance in construction, industrial fabrication, and mechanical applications, while international equivalents (A36, SS400, S235JR) make it easy to source worldwide.
