Q355NB Steel Plate GB/T 1591 Supplier

Q355NB, also searched as GB/T 1591 Q355NB, Q355NB steel plate, Q355NB plate and Q355 NB, is the 355 MPa quality-grade-B grade delivered normalized or normalizing-rolled in GB/T 1591-2018. Q is the yield symbol, 355 is the thin-plate minimum yield in MPa, N is the delivery letter, and B is the quality letter for Charpy impact at +20°C.

The N is the point of this page. Hot-rolled Q355B has no N. Thermomechanical Q355MB has an M. A hot-rolled certificate cannot be stamped NB. A TMCP certificate cannot be stamped NB. Grade C is 0°C. D is −20°C. E is −40°C. The 2018 edition replaced Q345 with Q355, so an old Q345NB drawing is reviewed against Q355NB, not silently swapped.

The closest process comparison is EN 10025-3 S355N, a normalized fine-grain grade, but that letter is tested at −20°C. EN 10025-2 S355JR is +20°C and is closer in impact temperature, but it is not an N grade. EN 10025-3 S355NL is colder. On the US side, ASTM A572 Gr.50 is 50 ksi / 345 MPa and is not an NB twin. JIS G3106 SM490B is the usual Japanese comparison. Dual mark only when both books are fully met. See EN 10025-3 and high strength low alloy plates.

SHH STEEL is a global steel mill sourcing partner and steel manufacturer and exporter, mill-direct, China origin. We source Q355NB from first-line structural mills, print heat analysis and product analysis when ordered, and ship plate to fabricators in the United States, Europe, the Middle East, Southeast Asia, Africa and South America. Related pages include structural steel plates and the products index.

Nearby pages that buyers compare, but must not swap blindly, include EN 10025-3 S355N, EN 10025-2 S355JR and ASTM A572 Gr.50.

Heat analysis is the mill ladle table in GB/T 1591-2018 for normalized Q355. Product analysis, when ordered, follows GB/T 222. Q355NB is a carbon-manganese HSLA plate. Grade B allows a wider phosphorus and sulfur window than grade D or E. That is acceptable at +20°C. It is not a reason to use Q355NB on a −20°C drawing. Mills may add Nb, V or Ti. The certificate shows the elements actually used.

Heat Analysis and Product Analysis — GB/T 1591 Q355NB, normalized

Carbon equivalent is limited by thickness in the standard. The N route often has a different CEV window from hot-rolled Q355B. If the purchase order writes product analysis, SHH STEEL prints both columns and the thickness band used for the tensile test. Do not treat this chemistry as quenched-and-tempered GB/T 16270 Q460C.

Buyers search Q355NB mechanical properties, Q355NB yield strength, GB/T 1591 Q355NB tensile and Q355NB impact 20°C.

Tensile and impact — GB/T 1591 Q355NB, normalized

Impact energy is the average of three longitudinal Charpy V-notch specimens, commonly 34 J minimum at +20°C. One value may fall below the table, but not below 70% of that value. Write a higher energy on the order if the owner requires it.

Yield steps down with thickness. A 355 MPa name on 12 mm plate is not the minimum on a 40 mm flange. 355 MPa is about 51.5 ksi. ASTM A572 Gr.50 is 50 ksi and is not this book. SHH STEEL quotes the thickness band and the N condition on the offer.

Density is 7.85 g/cm³. Hardness is not a design value for this grade. Z15, Z25 or Z35 through-thickness tensile is an extra, not part of the B letter.

There is no official one-to-one substitute for Q355NB. What buyers compare is a 355 MPa normalized plate tested at +20°C.

EN 10025-3 S355N is the process comparison, but it is tested at −20°C. EN 10025-3 S355NL is colder. EN 10025-2 S355JR matches the +20°C letter and does not match the N route. EN 10025-4 S355M is TMCP and closer to Q355MB. In the United States, ASTM A572 Gr.50 is 50 ksi / 345 MPa. ASTM A36 is 36 ksi and is well below this yield. In Japan, JIS G3106 SM490B is the usual comparison. SHH STEEL will not stamp EN 10025-3 S355N or ASTM A572 Gr.50 on a Q355NB certificate unless the purchase order names both books and both tables are met.

Buyers pick Q355NB when a building, bridge member or welded fabrication wants about 355 MPa yield, a normalized or normalizing-rolled condition, and impact at +20°C. Search phrases such as Q355NB steel plate and GB/T 1591 Q355NB all point here.

It is the wrong plate when the drawing says hot rolled only. That work is Q355B. It is the wrong plate when the drawing says TMCP. That work is Q355MB, and the European file is often EN 10025-4 S355M. It is the wrong plate for a 0°C file. That work is Q355NC. It is the wrong plate for a −20°C file. That work is Q355ND, and the European file is often EN 10025-3 S355N. It is the wrong plate for a quenched-and-tempered boom. That work is GB/T 16270. It is the wrong plate for a pressure vessel. That work sits on ASTM A516 or pressure vessel steel plates.

SHH STEEL supplies this plate when the drawing names GB/T 1591, quality grade B, and the N condition at 355 MPa.

Q355NB is a weldable normalized HSLA structural plate. Carbon is controlled, and many heats use Nb, V or Ti. A procedure written for ASTM A36 can be a starting point on thin plate, but it is not a finished WPS for thick Q355NB. Carbon equivalent on the N route is not the same window as hot-rolled Q355B.

Typical consumables are matching 50 ksi / 355 MPa low-hydrogen electrodes or wires. E7018-class electrodes are common on shop joints that do not need full plate strength in the weld metal. A procedure written for EN 10025-3 S355N is a useful process reference after the impact temperature is checked. Preheat follows thickness, hydrogen and the approved WPS. Thick plate and restrained joints need more preheat than a 10 mm web.

The fabricator owns the WPS. SHH STEEL can share mill heat data, product analysis and carbon equivalent for that review. Do not use a Q355NB procedure on Q355MB without checking the TMCP carbon equivalent.

Usual delivery from SHH STEEL for Q355NB is normalized or normalizing rolled. The plate is not hot rolled as Q355B and not thermomechanical rolled as Q355MB.

Normalizing is typically about 880–920°C, followed by air cooling, unless the mill uses a normalizing-rolling route that the standard accepts for the N letter. Do not order Q355NB as quenched and tempered. That route belongs to GB/T 16270. Stress relief after fabrication, if used, should be agreed before cutting.

The certificate lists GB/T 1591 Q355NB, heat number, delivery condition, heat analysis, product analysis when ordered, tensile by thickness band, and +20°C impact. Certificates may be EN 10204 3.1 or EN 10204 3.2. Dual marking to EN 10025-3 S355N is available only when both books are fully met.

Usual supply range from SHH STEEL for Q355NB steel plate:

• Thickness: commonly 8 mm – 100 mm, heavier plate to 150 mm by enquiry
• Width: 1500 mm – 3000 mm, wider by enquiry
• Length: 3000 mm – 12000 mm

Cut-to-size webs, flanges, base plates and gussets are available. Browse more sizes on structural steel plates.

Dimensional limits for Q355NB follow GB/T 709 unless the purchase order names EN 10029 or another table.

Typical thickness tolerance idea for Q355NB plate

Width on 1500–3000 mm plate is commonly held to about +20 / 0 mm or ±25 mm unless a tighter extra is named. Length on 3000–12000 mm plate is commonly held to about +50 / 0 mm. Flatness follows the agreed class. SHH STEEL will not assume a zero-minus extra on Q355NB unless the order says so.

Q355NB already defines 355 MPa yield, normalized delivery and +20°C impact. Extra items still have to be written on the purchase order.

Book name. Write GB/T 1591 Q355NB. Do not write only Q355, and do not write Q355B if the mill must stamp N.

Impact. Grade B is +20°C. Write a higher energy if the owner requires it. Do not expect a −20°C result unless the grade is changed to Q355ND.

Delivery condition. Write normalized or normalizing rolled. Write Q355B if hot rolled is enough. Write Q355MB if TMCP is required.

EN or US comparison. Write EN 10025-3 S355N or ASTM A572 Gr.50 only if dual mark is required and both tables are met.

Product analysis. Write it if the file needs the second chemistry column.

Through-thickness. Z15, Z25 or Z35 when the joint is loaded through the thickness.

NDE. UT to GB/T 2970 or the named class.

Identification. Heat number, Q355NB, thickness and mill logo.

Third-party witness. EN 10204 3.2 with SGS, TÜV, BV, ABS or the inspector named.

Q355NB is the plate for a 355 MPa normalized file tested at +20°C. It is the wrong plate for a painted weathering facade that needs corten. It is the wrong plate for a 690 MPa QT boom under GB/T 16270.

SHH STEEL sources Q355NB from first-line Chinese structural mills and ships it on worldwide terms. Partner mills include Wuyang (Wugang), Angang, Shougang, Hanye, Anyang Iron and Steel, Baosteel, Xinyu, Xingcheng and other qualified mills when the size requires it.

Mill test certificates are issued to EN 10204 3.1 as standard. EN 10204 3.2 is arranged when the order names a third-party hold point.

Usual rolling thickness: 8 mm, 10 mm, 12 mm, 16 mm, 20 mm, 25 mm, 30 mm, 40 mm, 50 mm, 60 mm, 80 mm, 100 mm. Heavier plate is confirmed before order.

Processing: CNC or flame cutting, bevel, flattening, shot blast, UT to the named class.

Trade terms: FOB Shanghai main, CIF destination available. Payment: TT, LC, or TT + LC.

Ocean time from Shanghai: US West 14–18 days; US Gulf 28–35 days; Rotterdam / Antwerp 28–35 days; Jebel Ali 18–25 days; Singapore 7–12 days; other ports quoted.

Third-party: SGS, TÜV, BV, ABS, CCS, GL, VL, DNV, RINA, NK, KR, or the inspector named.

SHH STEEL is a global steel mill sourcing partner with mill partnerships in China. We supply GB, ASTM, ASME, EN, DIN and JIS steel to buyers in the United States, Europe, the Middle East, Southeast Asia, Africa and South America. Origin is mill-direct, China origin.

SHH STEEL has supplied steel plates to the USA, Mexico, Argentina, Peru, El Salvador, Spain, Netherlands, Germany, UAE, Saudi Arabia, South Africa, India, Thailand, Singapore, Vietnam, the Philippines, Japan and Korea.

Typical lead time: ex-stock 5–7 days when an N heat is in yard; standard normalizing about 30–45 days; 3.2 inspection about 40–50 days.

SHH STEEL is a global steel mill sourcing partner and steel manufacturer and exporter, mill-direct, China origin. For Q355NB that means mill-direct structural price, not a multi-layer stockist mark-up. We buy from mills that can actually normalize or normalizing-roll the heat, so the N is on the certificate and not only in the enquiry.

Delivery is short when the size is in rolling range: ex-stock 5–7 days, standard N heat about 30–45 days, 3.2 inspection about 40–50 days. Cutting, bevel and UT can run in the same window. FOB Shanghai is the main term. CIF to US West, US Gulf, Rotterdam, Jebel Ali and Singapore is quoted on the same file.

Experience on this grade is simple: print GB/T 1591 Q355NB, keep the normalized route, and do not ship Q355B or Q355MB as NB. We will not drop the N to save a furnace cycle, and we will not treat Q355NB as ASTM A36. If the drawing only needs hot-rolled plate, we will move the inquiry to Q355B and keep the price on the right condition.

Q355NB steel plate to GB/T 1591 is 355 MPa normalized structural plate with impact at +20°C. It is not hot-rolled Q355B and not TMCP Q355MB. The nearest European process comparison is EN 10025-3 S355N, and that grade is tested at −20°C. ASTM A572 Grade 50 is 345 MPa and is not a substitute. Whether the inquiry says Q355NB, GB/T 1591 Q355NB or Q355NB steel plate, SHH STEEL as a global steel mill sourcing partner supplies plate with Q355NB chemistry, heat and product analysis as ordered, GB/T 709 tolerances and EN 10204 3.1 or 3.2 certification.

SHH STEEL supplies Q355NB Steel Plate to the United States, Europe, the Middle East, Africa, Asia and the Americas for work that actually names the N condition.

Contact SHH STEEL for mill rolling, normalized Q355NB, cutting, UT, 3.2 inspection or a worldwide quotation.

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