③ 标准/对比页
Q355B Steel Properties
Q355B is the reference low-alloy high-strength structural plate under GB/T 1591: minimum yield 355 MPa for plates up to 16 mm, tensile range 470–630 MPa. Yunhao supplies Q355B/C/D/E from 8–100 mm thick, each shipment with a mill test certificate.
What Q355B IsQ355B is a low-alloy high-strength structural steel specified in GB/T 1591 (2018 edition). The number refers to its minimum yield strength: 355 MPa for plates up to 16 mm thick, stepping down gradually for thicker plates — the exact band for your thickness is confirmed on the mill test certificate. Quality grades B, C, D and E differ only in Charpy V-Notch impact temperature, sharing the same strength level.
Chemistry and WeldabilityFor grade B the standard caps silicon at 0.55 % and manganese at 1.60 %, while carbon, phosphorus and sulfur limits tighten as the quality grade rises from B to E. Micro-alloys such as niobium, vanadium and titanium carry the strength while keeping the carbon equivalent low enough for shop welding — verify the CEV for your heat number on the MTC.
Mechanical Anchor ValuesThree figures govern most buying decisions: yield ≥355 MPa (≤16 mm), tensile 470–630 MPa, and Charpy V energy ≥34 J at the grade temperature — +20 °C for B, 0 °C for C, −20 °C for D and −40 °C for E. If your design needs guaranteed low-temperature toughness, order grade D or E and require the impact result on the certificate.
Delivery Condition and SizesThe delivery condition for your order is fixed in the contract and stated on the mill test certificate. Yunhao's regular range runs 8–100 mm thick and 1500–3200 mm wide, MOQ from 25 t, dispatch in 15–30 days from Tianjin or Qingdao. Through-thickness Z quality (Z15/Z25/Z35 per GB/T 5313) can be added on request for heavy welded joints.
How to Pick Your GradeChoose the letter by lowest service temperature: B for ambient conditions, C down to 0 °C, D to −20 °C and E to −40 °C, all at 34 J minimum. For structures welded through the thickness, add a Z option and pair it with the GJC building-steel series for columns. Send your drawings and target thickness — we confirm grade, sizes and lead time with a quotation.
| Property | Value (≤16 mm) |
|---|---|
| Yield ReH | ≥ 355 MPa |
| Tensile Rm | 470–630 MPa |
| Impact KV2 | ≥ 34 J (+20 °C B / −20 °C D) |
| Thickness | 8–100 mm |