GB/T 16270 Q620D QT Carbon Steel Plate Supplier

Q620D, also searched as GB/T 16270 Q620D, Q620D QT plate, Q620D carbon steel plate, Q620D steel plate and Q620D quenched and tempered plate, is the 620 MPa quality-grade-D grade in GB/T 16270. That standard covers high-strength structural steel plate delivered quenched and tempered. Q is the yield symbol, 620 is the thin-plate minimum yield in MPa, and D is the quality letter for Charpy impact at −20°C.

Q620D is the middle impact letter in the 620 MPa family. C is 0°C. D is −20°C. E is −40°C. F is −60°C. About 90 ksi on a US drawing is the same yield number. Equipment builders use it when the frame needs 620 MPa and the site sees sub-zero nights, but the specification does not call for −40°C. It is not a substitute for Q620C, and it is not a substitute for Q620E.

EN 10025-6 does not have a −20°C letter. S620Q is tested at 0°C. S620QL is tested at −40°C and lines up more closely with Q620E. Q620D sits between those two. On the US side there is no official 90 ksi plate grade. A514 Grade Q is 100 ksi / 690 MPa QT plate, one step higher. ASTM A656 Grade 80 is 80 ksi / 550 MPa, one step lower. 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 Q620D 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 S620Q, S620QL and A514 Gr.Q.

Heat analysis is the mill ladle table in GB/T 16270. Product analysis, when ordered, follows GB/T 222. Grade D is tighter on phosphorus and sulfur than grade C, because the impact test is colder. 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 Q620D

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 weathering plate. Do not treat it as S355JR.

Buyers search Q620D mechanical properties, Q620D yield strength, GB/T 16270 Q620D tensile and Q620D impact −20°C.

Tensile and impact — GB/T 16270 Q620D

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 −20°C. Write a higher energy on the order if the owner requires it.

Yield steps down with thickness. A 620 MPa name on 20 mm plate is not the minimum on a 120 mm flange. 620 MPa is about 90 ksi. ASTM A514 is 100 ksi and is not this number. 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 Q620D. What buyers compare is a 620 MPa QT plate tested at −20°C.

In the United States there is no standard 90 ksi plate grade that matches this number. A514 Grade Q is 100 ksi / 690 MPa QT structural plate, closer to Q690D than to Q620D. ASTM A656 Grade 80 is 80 ksi / 550 MPa, closer to Q550. A572 Gr.65 is only 65 ksi. SHH STEEL will not stamp A514 on a Q620D certificate unless the purchase order names both books and both tables are met.

EN 10025-6 jumps from 0°C on S620Q to −40°C on S620QL. Q620D sits in the gap. Some files accept S620Q if an extra −20°C test is written. Others step up to S620QL. In Japan, SM570 is a welded structural grade and is well below this yield.

Buyers pick Q620D when a welded frame, boom or chassis wants 620 MPa yield, QT delivery and impact at −20°C. Search phrases such as Q620D steel plate, GB/T 16270 Q620D and Q620D QT plate all point here.

It is the wrong plate for a 0°C-only file that can use Q620C. It is the wrong plate for a −40°C mine site. That work is Q620E. It is the wrong plate for a 550 MPa file that was sized on Q550D. It is the wrong plate for a 100 ksi US file. That work is A514 Grade Q. 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 16270 and quality grade D at 620 MPa.

Q620D is weldable QT carbon plate. The plate has already been quenched and tempered. A procedure written for S355JR is not a Q620D procedure. A procedure qualified only on Q620C at 0°C may miss the −20°C coupon.

Typical consumables are matching 620–690 MPa low-hydrogen electrodes or wires, qualified on a QT 620 MPa family. E7018-class electrodes are under-matched if the joint must develop full plate strength. A procedure written for S620QL is a useful starting point after the −20°C test temperature is checked. An A514 procedure is a higher-strength reference, not a finished WPS for this grade.

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 Q620D is quenched and tempered. Austenitize typically in the 880–930°C range, quench, then temper in the window that holds 620 MPa yield and the −20°C impact. Exact temperatures stay on the mill process sheet.

Do not order Q620D as as-rolled or TMCP unless the contract leaves GB/T 16270. ASTM A514 is not a delivery instruction for this page. Stress relief after fabrication, if used, must stay below the original temper temperature.

The certificate lists GB/T 16270 Q620D, heat number, 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 S620Q or S620QL is available only when both books are fully met.

Usual supply range from SHH STEEL for Q620D QT carbon steel plate:

• Thickness: commonly 8 mm – 80 mm, heavier plate to 100 mm by enquiry
• Width: 1500 mm – 3500 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 Q620D follow GB/T 709 unless the purchase order names another table.

Typical thickness tolerance idea for Q620D QT plate

Width on 1500–3500 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 Q620D unless the order says so.

Q620D already defines 620 MPa yield, QT delivery and −20°C impact. Extra items still have to be written on the purchase order.

Book name. Write GB/T 16270 Q620D. Do not write only Q620D.

Impact. Grade D is −20°C. Write a higher energy if the owner requires it.

US comparison. Write A514 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.

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

Identification. Heat number, Q620D, thickness and mill logo.

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

Q620D is the plate for a 620 MPa QT file tested at −20°C. It is the wrong plate for a painted warehouse that can use S355JR. It is the wrong plate for a 100 ksi QT member.

SHH STEEL sources Q620D 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. 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 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 Q620D that means mill-direct QT price, not a multi-layer stockist mark-up. We buy from mills that already run the 620 MPa quench-and-temper route, so the heat carries the −20°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 Q620D, keep the QT route, and do not ship Q620C or A514 as Q620D. We will not change D to C to save a cold test, and we will not treat Q620D as S355. If the drawing needs −40°C, we will move the inquiry to Q620E and keep the price on the right grade.

GB/T 16270 Q620D QT carbon steel plate is 620 MPa quenched-and-tempered structural plate with impact at −20°C. The nearest US QT comparison is ASTM A514, which is 690 MPa and is not a substitute. Whether the inquiry says Q620D, GB/T 16270 Q620D, Q620D QT plate or Q620D carbon steel plate, SHH STEEL as a global steel mill sourcing partner supplies plate with Q620D chemistry, heat and product analysis as ordered, GB/T 709 tolerances and EN 10204 3.1 or 3.2 certification.

SHH STEEL supplies GB/T 16270 Q620D 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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