Q550C QT Carbon Steel Plate GB/T 16270 Supplier

Q550C, also searched as GB/T 16270 Q550C, Q550C QT plate, Q550C carbon steel plate, Q550C steel plate and Q550C quenched and tempered plate, is the 550 MPa quality-grade-C grade in GB/T 16270. That standard covers high-strength structural steel plate delivered quenched and tempered. Q is the yield symbol, 550 is the thin-plate minimum yield in MPa, and C is the quality letter for Charpy impact at 0°C.

Q550C sits one step above Q500C. The extra 50 MPa lets equipment builders thin a boom web or a chassis rail that was heavy in 500 MPa plate. It is still a QT carbon plate, not a stainless grade and not a pressure-vessel grade. A certificate that only says Q550 under another book does not meet this page.

Quality grade C means the impact test is at 0°C. D is −20°C. E is −40°C. F is −60°C. Q550C is the right letter for temperate fabrication and mild outdoor service. If the drawing shows winter design at −40°C, the letter is E, not C.

The closest European name is EN 10025-6 S550Q. Both are about 550 MPa QT plate tested at 0°C. S550QL is −40°C and lines up with Q550E. S550QL1 is −60°C and lines up with Q550F. Dual mark only when both books are fully met. See EN 10025-6 steel plate.

SHH STEEL is a global steel mill sourcing partner and steel manufacturer and exporter, mill-direct, China origin. We source Q550C from first-line QT 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 high strength low alloy plates and structural steel plates.

Nearby pages that buyers compare, but must not swap blindly, include S550Q, S550QL and S500Q.

Heat analysis is the mill ladle table in GB/T 16270. Product analysis, when ordered, follows GB/T 222. Q550C is a low-alloy QT carbon plate. Mills add Nb, V, Ti or Al for grain refinement, and may add Cr, Ni, Mo or B by thickness. The certificate shows the elements actually used.

Heat Analysis and Product Analysis — GB/T 16270 Q550C

Grade C allows a slightly wider phosphorus and sulfur window than grade E or F. That is acceptable at 0°C. It is not a reason to use Q550C on a −40°C drawing. If the file needs product analysis, SHH STEEL prints both columns and the thickness band used for the mechanical test.

Do not treat this chemistry as weathering plate. Do not treat it as S355JR.

Buyers search Q550C mechanical properties, Q550C yield strength, GB/T 16270 Q550C tensile and Q550C impact 0°C.

Tensile and impact — GB/T 16270 Q550C

Impact energy is the average of three longitudinal Charpy V-notch specimens. One value may fall below the table, but not below 70% of that value. A typical production heat is at or above 34 J at 0°C. Write a higher energy on the order if the owner requires it.

Yield steps down with thickness. A 550 MPa name on 20 mm plate is not the minimum on a 120 mm flange. SHH STEEL quotes the thickness band on the offer.

Density is 7.85 g/cm³. Hardness after temper is a mill control, not a design value. Z15, Z25 or Z35 through-thickness tensile is an extra.

There is no official one-to-one substitute for Q550C. What buyers compare is a 550 MPa QT plate tested at 0°C.

The usual European pair is S550Q. S550QL is colder and closer to Q550E. S500Q is the 500 MPa neighbour. SHH STEEL will not stamp S550Q on a Q550C certificate unless both books are fully met.

In the United States, A572 Grade 65 is below this yield and is not this QT book. A514 is a 100 ksi family. In Japan, SM570 is a welded structural grade, not this plate. In China, a GB/T 1591 Q550 heat is a different delivery route.

Buyers pick Q550C when a welded frame, boom or chassis wants 550 MPa yield, QT delivery and impact at 0°C. Search phrases such as Q550C steel plate, GB/T 16270 Q550C and Q550C QT plate all point here.

It is the wrong plate for a −40°C mine site. That work is Q550E. It is the wrong plate for a 500 MPa file that was sized on Q500C. Raising the grade without a design check can change weld procedure and deflection. It is the wrong plate for a 690 MPa boom. That work is Q690C or Q690E. It is the wrong plate for a pressure vessel. That work sits on ASTM A516 or pressure vessel steel plates. It is the wrong plate for an unpainted weathering girder.

SHH STEEL supplies this plate when the drawing names GB/T 16270 and quality grade C at 550 MPa.

Q550C is weldable QT carbon plate. Carbon is controlled, but the plate has already been quenched and tempered. A procedure written for S355JR is not a Q550C procedure. A procedure qualified only on Q500C may be under-matched.

Typical consumables are matching 550–620 MPa low-hydrogen electrodes or wires, qualified on a QT 550 MPa family. E7018-class electrodes are under-matched if the joint must develop full plate strength. A procedure written for S550Q is the usual starting point.

Preheat follows thickness, hydrogen and the approved WPS. Interpass temperature should stay below the mill temper range, or local yield can drop. After heavy cold forming, a stress relief may be required. The fabricator owns the WPS. SHH STEEL can share mill heat data, product analysis and carbon equivalent for that review.

Usual delivery from SHH STEEL for Q550C is quenched and tempered. Austenitize typically in the 880–930°C range, quench, then temper in the window that holds 550 MPa yield and the 0°C impact. Exact temperatures stay on the mill process sheet.

Do not order Q550C as as-rolled or TMCP unless the contract leaves GB/T 16270. Stress relief after fabrication, if used, must stay below the original temper temperature.

The certificate lists GB/T 16270 Q550C, heat number, heat analysis, product analysis when ordered, tensile by thickness band, and 0°C impact. Certificates may be EN 10204 3.1 or EN 10204 3.2. Dual marking to S550Q is available only when both books are fully met.

Usual supply range from SHH STEEL for Q550C QT carbon steel plate:

• Thickness: commonly 8 mm – 100 mm, heavier plate to 150 mm by enquiry
• Width: 1500 mm – 3800 mm
• Length: 3000 mm – 12000 mm

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

Dimensional limits for Q550C follow GB/T 709 unless the purchase order names another table.

Typical thickness tolerance idea for Q550C QT plate

Width on 1500–3800 mm plate is commonly held to about ±20–25 mm unless a tighter extra is named. Length on 3000–12000 mm plate is commonly held to about +50 / 0 mm or ±25 mm by mill practice. Flatness after QT follows the agreed class. SHH STEEL will not assume a zero-minus extra on Q550C unless the order says so.

Q550C already defines 550 MPa yield, QT delivery and 0°C impact. Extra items still have to be written on the purchase order.

Book name. Write GB/T 16270 Q550C. Do not write only Q550C.

Impact. Grade C is 0°C. Write a higher energy if the owner requires it.

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.

Heat-treatment record. QT temperatures when the inspector asks.

Identification. Heat number, Q550C, thickness and mill logo.

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

Q550C is the plate for a 550 MPa QT file tested at 0°C. It is the wrong plate for a painted warehouse that can use S355JR. It is the wrong plate for a 690 MPa member.

SHH STEEL sources Q550C from first-line Chinese QT 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: 10 mm, 12 mm, 16 mm, 20 mm, 25 mm, 30 mm, 32 mm, 40 mm, 50 mm, 60 mm, 80 mm, 100 mm.

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 plate is in yard; standard QT rolling about 35–45 days; 3.2 inspection about 45–60 days.

SHH STEEL is a global steel mill sourcing partner and steel manufacturer and exporter, mill-direct, China origin. For Q550C that means mill-direct QT price, not a multi-layer stockist mark-up. We buy from mills that already run the 550 MPa quench-and-temper route, so the heat carries the 0°C impact without a second upgrade charge.

Delivery is short when the size is in rolling range: ex-stock 5–7 days, standard heat about 35–45 days, 3.2 inspection about 45–60 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 16270 Q550C, keep the QT route, and do not ship Q500C as Q550C. We will not change C to E on the certificate to win an order, and we will not treat Q550C as S355. If the drawing needs −40°C, we will move the inquiry to Q550E and keep the price on the right grade.

Q550C QT carbon steel plate to GB/T 16270 is 550 MPa quenched-and-tempered structural plate with impact at 0°C. Whether the inquiry says Q550C, GB/T 16270 Q550C, Q550C QT plate or Q550C carbon steel plate, SHH STEEL as a global steel mill sourcing partner supplies plate with Q550C chemistry, heat and product analysis as ordered, GB/T 709 tolerances and EN 10204 3.1 or 3.2 certification.

SHH STEEL supplies Q550C QT Carbon Steel Plate to the United States, Europe, the Middle East, Africa, Asia and the Americas for work that actually names this grade.

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

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