③ 标准/对比页
ASTM A36 vs Q235B: Close Grades, Different Systems
ASTM A36 and Q235B are the general-purpose structural plates of their respective systems, and they are close in strength. They are not equivalents: A36 carries a nominal minimum yield of 250 MPa against 235 MPa for Q235B, and the two standards verify chemistry and toughness differently. Selection should follow the project's governing standard.
Strength BandsASTM A36/A36M sets a minimum yield of 250 MPa (36 ksi) with tensile 400–550 MPa (58–80 ksi). GB/T 700 sets Q235B at 235 MPa minimum yield with 370–500 MPa tensile. The nominal yield gap is 15 MPa in A36's favor — real, but small enough that both grades cover most general structural duties when loads are modest.
Why They Are Not InterchangeableA36 chemistry limits flex with plate thickness and manganese content, so the grade is defined by its mechanical floor rather than a fixed analysis. Q235B keeps explicit caps for C, Si, Mn, P and S under GB/T 700. Projects governed by American specifications call out A36; Chinese and many Asian project specifications call out Q235B — mixing the two on one drawing invites review cycles.
Toughness and ImpactQ235B carries a B quality mark that references impact testing at +20 ℃ under GB/T 700; confirm the exact requirement on the mill test certificate. A36 has no mandatory Charpy tier in its base specification — if the design needs guaranteed low-temperature toughness, that is a conversation about upgrading the grade, not just swapping labels.
Selection PracticeLet the governing standard decide first: A36 for US-system projects, Q235B for GB-system projects. Where a drawing accepts either, compare the yield margin the connection design actually uses and note the 15 MPa nominal difference. Yunhao supplies both grades in the same 8–100 mm thickness window and 1500–3200 mm widths.
Ordering and DocumentsBoth grades ship in 15–30 days from Tianjin or Qingdao at MOQ 25 t, each heat with a mill test certificate declaring the actual standard, chemistry and mechanical results. If the project needs A36-marked material for American review or Q235B for a Chinese design institute, say so on the PO — mills roll and mark accordingly.
| Item | ASTM A36 | Q235B |
|---|---|---|
| Governing standard | ASTM A36/A36M | GB/T 700 |
| Minimum yield | ≥250 MPa (36 ksi) | ≥235 MPa |
| Tensile Rm | 400–550 MPa (58–80 ksi) | 370–500 MPa |
| Nominal yield gap | +15 MPa vs Q235B | — |
| Yunhao supply window | 8–100 mm, 1500–3200 mm | 8–100 mm, 1500–3200 mm |