ASTM A709 QST 50 Steel Shape | A709 QST 50 Bridge Shape Steel supplier
What is ASTM A709 QST 50 Steel Shape?
ASTM A709 QST 50, also searched as A709 QST50, A709-QST50, A709 QST Gr.50, A913 Grade 50 and A709 QST 50 50ksi, is the 50 ksi quenched-and-self-tempered shape grade in ASTM A709/A709M. That book covers structural steel for bridges. QST 50 is built on A913/A913M Grade 50. It is rolled as W-shapes, not as a standard plate grade.
QST means the section is quenched from the rolling heat and self-tempers on the cooling bed. Carbon stays low so the shape welds like a modern 50 ksi section. That is not Grade 50S. Grade 50S follows A992 as-rolled practice. QST 50S is the A913 sister with the S suffix. A709 Grade 50 is the A572-50 plate twin.
A certificate that only says A913 Grade 50 is not an A709 QST 50 member unless the purchase order also meets A709 toughness and identification. Do not treat QST 50 as A572 Gr.50 plate. Do not treat it as A36. Do not treat it as Grade 50W. A709 says HPS 70W and HPS 100W shall not be substituted for QST 50. Do not treat A709 as a pressure-vessel product. That work sits on ASTM A516 or pressure vessel steel plates.
General requirements follow A6/A6M. Yield is 50 ksi / 345 MPa min. Tensile is 65 ksi / 450 MPa min. Density is 7.85 g/cm³.
SHH STEEL is a global steel mill sourcing partner and steel manufacturer & exporter (mill-direct, China origin). We source A709 QST 50 / A913 Grade 50 shapes from first-line Chinese mills, print heat and product analysis when ordered, record the impact zone when named, and ship sections to fabricators in the United States, Europe, the Middle East, Southeast Asia, Africa and South America.
Related category pages: structural steel plates, ASTM A572 A572M structural steel plates, carbon steel plates and high strength low alloy plates.
Material Specification
| Specification Element | Requirement | SHH STEEL Compliance |
|---|---|---|
| Product book | ASTM A709/A709M QST 50 | Confirmed |
| Base shape book | A913/A913M Grade 50 | Confirmed |
| Other search names | A709 QST50, A709-QST50, A913 Gr.50 | Covered |
| Product form | QST W-shapes | Confirmed |
| Process | Quench and self-temper | Confirmed |
| General requirements | A6 / A6M | Confirmed |
| Yield | 50 ksi / 345 MPa min | Confirmed |
| Tensile | 65 ksi / 450 MPa min | Confirmed |
| Weathering | No | Confirmed |
| Product analysis | A6 product column when ordered | Confirmed |
| Toughness | A709 zone / FCM as ordered | Confirmed |
| Supply role | Global steel mill sourcing partner | SHH STEEL |
| Certification | EN 10204 3.1 or 3.2 / third-party | As ordered |
Nearby pages that buyers compare, but must not swap blindly, include A572 Gr.50, EN 10025-2 S355JR, EN 10025-2 S355J2 and JIS G3106 SM490B.
Chemical Composition
QST 50 chemistry follows A913 Grade 50. Carbon is held down for welding after the QST cool. Heat analysis is the mill table. Product analysis, when ordered, follows A6 product tolerances on that heat.
Heat Analysis and Product Analysis — ASTM A709 QST 50 (A913 Gr.50 basis)
| Element | Heat analysis (%) | Product analysis (%) |
|---|---|---|
| Carbon (C), max | 0.12 | 0.15 |
| Manganese (Mn), max | 1.60 | 1.66 |
| Phosphorus (P), max | 0.030 | 0.035 |
| Sulfur (S), max | 0.030 | 0.035 |
| Silicon (Si), max | 0.40 | 0.45 |
| Copper (Cu), max | 0.35 | 0.38 |
| Nickel (Ni), max | 0.25 | 0.28 |
| Chromium (Cr), max | 0.25 | 0.29 |
| Molybdenum (Mo), max | 0.07 | 0.08 |
| Vanadium (V), max | 0.06 | 0.07 |
| Niobium (Nb), max | 0.05 | 0.06 |
Carbon at 0.12% max is the A913 signature. Grade 50S / A992 allows 0.23% carbon. If the purchase order writes product analysis, SHH STEEL prints both columns.
Do not treat this chemistry as Grade 50S. Do not treat it as Grade 50W. Do not treat it as S355JR unless both books are met.
Mechanical Properties
Buyers search A709 QST 50 mechanical properties, A709 QST50 yield, A913 Grade 50 and A709-QST50 tensile.
Tensile Properties — ASTM A709 QST 50 / A913 Grade 50 shapes
| Property | Requirement |
|---|---|
| Yield strength, min | 50 ksi / 345 MPa |
| Tensile strength, min | 65 ksi / 450 MPa |
| Elongation in 8 in. (200 mm), min | 18% |
| Elongation in 2 in. (50 mm), min | 21% |
Toughness is the A709 extra. Write non-FCM or FCM, zone and temperature. A silent A913 Grade 50 heat is not an FCM shape.
Density is 7.85 g/cm³.
Material Comparison
| Grade | Book | Form | Process | Yield | Swap? |
|---|---|---|---|---|---|
| A709 Grade 50 | A709 | Plate | As-rolled | 345 MPa | No |
| A709 Grade 50S | A709 + A992 | Shapes | As-rolled | 345 MPa | No |
| A709 QST 50 | A709 + A913 | Shapes | QST | 345 MPa | This page |
| A709 QST 50S | A709 + A913 | Shapes | QST | 345 MPa | Sister only |
| A709 QST 65 | A709 + A913 | Shapes | QST | 450 MPa | No |
| A709 QST 70 | A709 + A913 | Shapes | QST | 485 MPa | No |
| S355JR | EN 10025-2 | Sections | As-rolled | 355 MPa | Comparison only |
Equivalent Material Grades
There is no official one-to-one worldwide twin for A709 QST 50. What buyers compare is a 345 MPa painted QST shape.
In the United States the chemistry and process twin is A913 Grade 50. Grade 50S is A992. QST 50S is the A913 S sister. QST 65 and QST 70 are higher A913 yield grades.
In Europe compare S355JR, S355J2 and S355N sections. QST is not TMCP and not QT plate. See EN 10025-2 and EN 10025-4.
In Japan compare SM490A and SM490B. In China compare GB/T 1591 Q355B / Q355C / Q355D sections. Dual mark only when both books are fully met.
| Designation | Country / region | Standard | Notes |
|---|---|---|---|
| A709 QST 50 / QST50 | USA | ASTM A709/A709M | Name on this page |
| A913 Grade 50 | USA | A913/A913M | Process twin |
| A709 Grade 50S | USA | A709 + A992 | As-rolled shape |
| A709 QST 50S | USA | A709 + A913 | S sister |
| S355J2 | Europe | EN 10025-2 | Section comparison |
| SM490B | Japan | JIS G3106 | Welded structure comparison |
| Q355B / Q355D | China | GB/T 1591 | Strength comparison |
Bridge Shape Service
Buyers pick A709 QST 50 when a painted W-shape wants 50 ksi yield, low carbon and an A709 stamp on an A913 route. Search phrases such as A709 QST50, A709 QST 50, A913 Grade 50 and A709-QST50 all point here.
It is the wrong product for a plate girder web. That work is A709 Grade 50 plate. It is the wrong product for an A992 as-rolled shape file that does not name QST. That work is Grade 50S. It is the wrong product for an unpainted weathering girder. That work is Grade 50W. It is the wrong product for a pressure vessel. That work is A516 Grade 70.
SHH STEEL will ask for the W-depth before rolling.
Weldability
ASTM A709 QST 50 is weldable low-carbon QST shape steel. Treat welding as bridge production welding when the member is FCM.
Typical consumables are AWS A5.1 E7018 or matching GMAW / SAW wires qualified on a 50 ksi A913 family. A procedure written for Grade 50S / A992 is a starting point after carbon and CEV are checked. A procedure written for Grade 50W must account for copper and chromium. A procedure written for A36 is under-matched.
Preheat follows flange thickness and hydrogen control. The fabricator owns the WPS. SHH STEEL can share mill heat data, product analysis and CEV for that review.
Heat Treatment and Delivery Condition
Usual delivery from SHH STEEL for A709 QST 50 is quenched and self-tempered A913 Grade 50 shapes. The mill quenches from the rolling heat. There is no separate furnace temper like HPS 100W plate.
Do not order QST 50 as QT A514 plate or as HPS 70W plate. The certificate lists ASTM A709 QST 50 and A913 Grade 50 when dual-marked; heat number; heat analysis and product analysis when ordered; tensile to the 50 ksi table; impact zone when ordered. Certificates may be EN 10204 3.1 or EN 10204 3.2.
Dimensions
Usual supply from SHH STEEL for A709 QST 50 bridge shape steel:
- Product form: QST W-shapes
- Depth range: common W12 to W36, other depths by enquiry
- Length: 6 m – 18 m, longer by enquiry
Plate girders stay on the Grade 50 plate page. Browse related plate sizes on structural steel plates, ASTM A572 plates and the products index.
Tolerances
Dimensional limits for ASTM A709 QST 50 follow A6 / A6M shape tolerances unless the purchase order names another table.
Flange width, depth, web thickness, out-of-square and camber follow the A6 W-shape tables. Length is commonly held to +50 / 0 mm or the A6 plus tolerance. Straightness follows A6 unless a tighter bridge extra is written. SHH STEEL will not assume a plate-thickness extra on a W-shape order.
Supplementary Requirements
QST 50 already defines the A913 50 ksi table and the QST route. Extra items still have to be written on the purchase order.
Book name. Write ASTM A709 QST 50. Write A913 Grade 50 as the dual mark.
Section size. Write the W designation.
Impact zone. Write non-FCM or FCM, zone and temperature.
Product analysis. Write it if the file needs the second chemistry column.
NDE. UT on flanges when named.
Identification and stamping. Heat number, A709 QST 50, size and mill logo.
Third-party witness. EN 10204 3.2 with SGS, TÜV, BV, ABS or the inspector named.
Applications
| Industry | Typical components |
|---|---|
| Highway bridges | A709 QST 50 / QST50 W-stringers |
| Railway bridges | Painted A913 shapes from SHH STEEL |
| Approach spans | W14 / W16 / W18 / W21 / W24 QST shapes |
| Comparison vs 50S | QST50 next to A709 Grade 50S |
| Comparison vs Grade 50 plate | QST50 next to A709 Grade 50 plate |
| Comparison vs S355J2 | QST50 next to S355J2 |
| Comparison vs SM490B | QST50 next to SM490B |
A709 QST 50 is the product for a painted 50 ksi QST shape file. It is the wrong product for a plate-girder web. That work is Grade 50 plate. It is the wrong product for a QT 100 ksi flange. That work sits on A514 Grade Q or HPS 100W.
Supply Capability
SHH STEEL sources ASTM A709 QST 50 from first-line Chinese section mills that run an A913 QST route and ships it on worldwide terms. Partner mills include Angang, Shougang, Maanshan, Laigang, Rizhao, Baotou and other qualified mills when the size requires it. Plate partners such as Wuyang, Hanye, Xinyu and Xingcheng cover A709 plate grades on the same project.
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. Dual marking to A913 Grade 50 is the usual route.
Usual rolling: common W12–W36 depths, 12 m stock lengths, cut-to-length on request.
Processing: cutting, coping, drill, blast and paint, UT on flanges when named.
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.
Global Delivery & Markets
SHH STEEL is a global steel mill sourcing partner with mill partnerships in China. We supply ASTM, ASME, EN, DIN, JIS and GB 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 products 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 the section is in yard; standard QST rolling about 35–45 days; impact zone or 3.2 inspection about 45–60 days.
Why Choose SHH STEEL
SHH STEEL is a global steel mill sourcing partner and steel manufacturer & exporter (mill-direct, China origin). For A709 QST 50 that means mill-direct A913 price, not a multi-layer stockist mark-up on a QST heat. We buy from section mills that already run the low-carbon QST route, so the unit price stays competitive and the heat can still carry the A709 impact zone.
Delivery is short when the size is in range: ex-stock 5–7 days, standard heat about 35–45 days, 3.2 inspection about 45–60 days. Coping, drill, blast and paint 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 A709 QST 50 and A913 Grade 50, keep carbon at 0.12% max, and do not ship Grade 50S as QST 50. We will not skip the QST route on the certificate, will not stamp 50W chemistry as QST 50, and will not treat A709 as warehouse A36. If the file is A992 as-rolled, we will move the inquiry to Grade 50S and keep the price on the right product.
FAQ
- What is ASTM A709 QST 50 steel?
- ASTM A709 QST 50, also searched as A709 QST50, A709-QST50 and A913 Grade 50, is 50 ksi / 345 MPa quench-and-self-temper bridge shape steel. It is W-shapes, not plate. SHH STEEL supplies this product worldwide as a global steel mill sourcing partner.
- Is A709 QST 50 the same as A913 Grade 50?
- Process and chemistry follow A913 Grade 50. A709 QST 50 also needs the A709 stamp and the ordered impact zone.
- Is A709 QST 50 the same as A709 Grade 50S?
- No. Grade 50S is as-rolled A992. QST 50 is A913 quench-and-self-temper, with 0.12% max carbon.
- Is A709 QST 50 the same as A709 Grade 50 plate?
- No. Grade 50 is A572-50 plate. QST 50 is a shape grade
- Can SHH STEEL issue EN 10204 3.2 for A709 QST50?
- Yes. EN 10204 3.1 is standard. EN 10204 3.2 is arranged with SGS, TÜV, BV, ABS or the inspector named on the order.
Conclusion
ASTM A709 QST 50 Steel is 50 ksi / 345 MPa painted bridge shape steel built on A913 Grade 50 quench-and-self-temper practice, with A709 toughness when ordered. Whether the inquiry says ASTM A709 QST 50, A709 QST50, A709-QST50, A913 Grade 50 or A709 QST 50 50ksi, SHH STEEL as a global steel mill sourcing partner and steel manufacturer & exporter (mill-direct, China origin) supplies W-shapes with QST 50 chemistry, heat and product analysis as ordered, and EN 10204 3.1 or 3.2 certification.
SHH STEEL supplies ASTM A709 QST 50 / A709 QST50 Bridge Shape Steel 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, dual A913 marking, FCM impact, cutting, blast, 3.2 inspection or a worldwide quotation.
ASTM A709 QST 50 Steel, A709 QST50, A913 Grade 50, QST 50 bridge shape, A709 QST 50 supplier, SHH STEEL

