Q355MB TMCP Steel Plate GB/T 1591 Supplier

Q355MB, also searched as GB/T 1591 Q355MB, Q355MB steel plate, Q355MB TMCP plate and Q355 MB, is the 355 MPa quality-grade-B grade delivered by thermomechanical controlled process in GB/T 1591-2018. Q is the yield symbol, 355 is the thin-plate minimum yield in MPa, M is the delivery letter, and B is the quality letter for Charpy impact at +20°C.

The M is the point of this page. Hot-rolled GB/T 1591 Q355B has no M. Normalized GB/T 1591 Q355NB has an N. A hot-rolled certificate cannot be stamped MB. A normalized certificate cannot be stamped MB. Grade C is 0°C. D is −20°C. E is −40°C. The full family sits on GB/T 1591. Do not drop a 355 MPa drawing onto a lower grade, and do not upgrade it to GB/T 1591 Q390NB without a price check.

The closest European comparison is EN 10025-4 S355M, a TMCP fine-grain grade. EN 10025-3 S355N is normalized and closer to Q355NB, and it is tested at −20°C. On the US side, ASTM A572 Gr.50 is 50 ksi / 345 MPa, one step lower, and it is not an MB twin. JIS G3106 SM490B is the usual Japanese comparison. Dual mark only when both books are fully met. See EN 10025-4 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 Q355MB from first-line structural mills that can actually run the TMCP schedule, 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 GB/T 1591 Q355C, GB/T 1591 Q355NB and ASTM A572 Gr.50.

Heat analysis is the mill ladle table in GB/T 1591-2018 for TMCP Q355. Product analysis, when ordered, follows GB/T 222. Q355MB is a microalloyed 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 Q355MB on a −20°C drawing. Mills may add Nb, V or Ti. The certificate shows the elements actually used. TMCP chemistry is often leaner than a normalized heat of the same yield, because the rolling schedule does part of the grain refinement.

Heat Analysis and Product Analysis — GB/T 1591 Q355MB, TMCP

Carbon equivalent is limited by thickness in the standard. The M route often has a lower CEV window than hot-rolled GB/T 1591 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. A colder hot-rolled file is GB/T 1591 Q355D, not this grade.

Buyers search Q355MB mechanical properties, Q355MB yield strength, GB/T 1591 Q355MB tensile and Q355MB impact 20°C.

Tensile and impact — GB/T 1591 Q355MB, TMCP

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 M 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.

A colder hot-rolled file is GB/T 1591 Q355E. A 420 MPa file is GB/T 1591 Q420B.

There is no official one-to-one substitute for Q355MB. What buyers compare is a 355 MPa TMCP plate tested at +20°C.

EN 10025-4 S355M is the process comparison, but it is tested at −20°C. EN 10025-3 S355N is normalized and closer to GB/T 1591 Q355NB. EN 10025-2 S355JR is +20°C and as-rolled, closer to GB/T 1591 Q355B. 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 10025-4 S355M or ASTM A572 Gr.50 on a Q355MB certificate unless the purchase order names both books and both tables are met.

Buyers pick Q355MB when a building, bridge member or welded fabrication wants about 355 MPa yield, a TMCP condition, and impact at +20°C. Search phrases such as Q355MB steel plate and GB/T 1591 Q355MB all point here. The family index is GB/T 1591.

It is the wrong plate when the drawing says hot rolled only. That work is GB/T 1591 Q355B. It is the wrong plate when the drawing says normalized. That work is GB/T 1591 Q355NB. It is the wrong plate for a 0°C file. That work is Q355MC, and the hot-rolled sister is GB/T 1591 Q355C. It is the wrong plate for a −20°C file. That work is Q355MD, and the normalized sister is GB/T 1591 Q355ND. It is the wrong plate for a −40°C file. That work is Q355ME, and the normalized sister is GB/T 1591 Q355NE. It is the wrong plate for a 390 MPa file. That work is GB/T 1591 Q390NC or GB/T 1591 Q390ND. It is the wrong plate for a 420 MPa file. That work is GB/T 1591 Q420NB or GB/T 1591 Q420D. It is the wrong plate for a 460 MPa file. That work is GB/T 1591 Q460C or GB/T 1591 Q460NC. 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 M condition at 355 MPa.

Q355MB is a weldable TMCP HSLA structural plate. Carbon is controlled, and many heats use Nb, V or Ti. A procedure written for ASTM A36 is not a finished WPS for thick Q355MB. Carbon equivalent on the M route is often lower than hot-rolled GB/T 1591 Q355B, which helps the root pass, but the TMCP microstructure still needs a qualified procedure.

Typical consumables are matching 50 ksi low-hydrogen electrodes or wires. E7018-class electrodes are common when the joint does not have to develop the full plate strength. A procedure written for ASTM A572 Gr.50 is a useful strength reference after chemistry is checked. Preheat follows thickness, hydrogen and the approved WPS. Heat input should stay inside the mill window. A very high heat input can soften the TMCP zone next to the weld.

The fabricator owns the WPS. SHH STEEL can share mill heat data, product analysis and carbon equivalent for that review. Do not use a Q355MB procedure on GB/T 1591 Q355NB without checking the normalized carbon equivalent. Do not use it on GB/T 1591 Q460NE either. That plate is a different yield and a different delivery letter.

Usual delivery from SHH STEEL for Q355MB is thermomechanical controlled process. The plate is not hot rolled as GB/T 1591 Q355B and not normalized as GB/T 1591 Q355NB.

TMCP combines controlled rolling and accelerated cooling. Finish rolling is held in the non-recrystallization range, then the plate is cooled on the run-out table to a finish temperature the mill records. Do not order Q355MB as quenched and tempered. That route belongs to GB/T 16270. Stress relief after fabrication, if used, should be agreed before cutting, because a high temper can move the TMCP properties.

The certificate lists GB/T 1591 Q355MB, 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 10025-4 S355M is available only when both books are fully met.

Usual supply range from SHH STEEL for Q355MB steel plate:

• Thickness: commonly 6 mm – 80 mm, heavier plate to 100 mm by enquiry
• Width: 1500 mm – 3500 mm, wider by enquiry
• Length: 3000 mm – 14000 mm

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

Dimensional limits for Q355MB follow GB/T 709 unless the purchase order names EN 10029 or another table.

Typical thickness tolerance idea for Q355MB plate

Width on 1500–3500 mm plate is commonly held to about +20 / 0 mm or ±25 mm unless a tighter extra is named. Length on 3000–14000 mm plate is commonly held to about +50 / 0 mm. Flatness follows the agreed class. TMCP plate can hold a tighter flatness than a heavy normalized plate of the same thickness, but SHH STEEL will not assume a zero-minus extra on Q355MB unless the order says so.

Q355MB already defines 355 MPa yield, TMCP delivery and +20°C impact. Extra items still have to be written on the purchase order.

Book name. Write GB/T 1591 Q355MB. Do not write only Q355, and do not write Q355B if the mill must stamp M. The family page is GB/T 1591.

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 Q355MD.

Delivery condition. Write thermomechanical controlled process. Write GB/T 1591 Q355B if hot rolled is enough. Write GB/T 1591 Q355NB if normalized is required.

EN or US comparison. Write EN 10025-4 S355M 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, Q355MB, thickness and mill logo.

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

Q355MB is the plate for a 355 MPa TMCP 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. A colder 460 MPa normalized file is GB/T 1591 Q460ND or GB/T 1591 Q460NE.

SHH STEEL sources Q355MB 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: 6 mm, 8 mm, 10 mm, 12 mm, 16 mm, 20 mm, 25 mm, 30 mm, 40 mm, 50 mm, 60 mm, 80 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 M heat is in yard; standard TMCP about 25–40 days; 3.2 inspection about 35–45 days.

SHH STEEL is a global steel mill sourcing partner and steel manufacturer and exporter, mill-direct, China origin. For Q355MB that means mill-direct structural price, not a multi-layer stockist mark-up. We buy from mills that can actually run the TMCP schedule, so the M 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 M heat about 25–40 days, 3.2 inspection about 35–45 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 Q355MB, keep the TMCP route, and do not ship GB/T 1591 Q355B or GB/T 1591 Q355NB as MB. We will not drop the M to save a cooling cycle, and we will not change B to a colder letter without a new test. If the drawing only needs hot-rolled plate, we will move the inquiry to Q355B and keep the price on the right condition. If the drawing needs 420 MPa normalized plate, we will move it to GB/T 1591 Q420NE or GB/T 1591 Q420ND.

Q355MB steel plate to GB/T 1591 is 355 MPa TMCP structural plate with impact at +20°C. It is not hot-rolled GB/T 1591 Q355B and not normalized GB/T 1591 Q355NB. The nearest European process comparison is EN 10025-4 S355M. ASTM A572 Grade 50 is 345 MPa and is not a substitute. Whether the inquiry says Q355MB, GB/T 1591 Q355MB or Q355MB TMCP plate, SHH STEEL as a global steel mill sourcing partner supplies plate with Q355MB chemistry, heat and product analysis as ordered, GB/T 709 tolerances and EN 10204 3.1 or 3.2 certification.

SHH STEEL supplies Q355MB Steel Plate to the United States, Europe, the Middle East, Africa, Asia and the Americas for work that actually names the M condition. The grade family is listed on GB/T 1591.

Contact SHH STEEL for mill rolling, TMCP Q355MB, cutting, UT, 3.2 inspection or a worldwide quotation.

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