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Q235B vs Q355B: Which Structural Steel Should You Specify?
Q235B vs Q355B: Which Structural Steel Should You Specify?
In Chinese steel specifications, Q235B E Q355B are the two workhorse structural grades. The difference is not subtle — it affects section size, weight and cost. Getting the choice right at the design stage saves money later.
What the Numbers Mean
IL “Q” stands for yield point (qufu), and the number is the minimum yield strength in MPa. Q235B yields at 235 MPa; Q355B yields at 355 MPa — roughly 50 % stronger. IL “B” means a Charpy V-notch impact test at +20 ° C..
| Proprietà | Q235B | Q355B |
|---|---|---|
| Prodotto (MPa) | ≥ 235 | ≥ 355 |
| Trazione (MPa) | 375 – 460 | 470 – 630 |
| Allungamento (%) | ≥ 26 | ≥ 21 |
| Rough equivalent | ASTM A36 / SS400 | ASTM A572 Gr.50 |
When to Use Q235B
Q235B is the right choice for general fabrication, light frames, fence posts, brackets and indoor structures where loads are moderate. It is cheap, easy to weld and widely available. Browse our Q235B channel, Q235B flat bar E Q235B welded pipe.
When to Step Up to Q355B
Use Q355B for bridges, crane booms, heavy machinery, truck frames and any section where a lighter weight is worth the small premium. See our Q355B round bar, Q355B angle E Q355B plate.
