Steel Q690Q
GB Q690Q · EN S690Q
Q690Q is a quenched and tempered high-strength structural plate to GB/T 16270, equivalent to EN S690Q, with 750 MPa yield, 830 MPa tensile, 16% elongation and about 260 HB (26 HRC).
Reference datasheet — Q690Q is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the QT condition
Q690Q tempers and conditions
Q690Q is supplied in 7 conditions, soft to hard. QT is the default FabDigit quotes; the values on this page are for it.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Q&T | Very heavy sections where 630 MPa minimum yield is acceptable; check hardenability with the mill. | 690 | 780 | 17 | 23 HRC | 7.2 % IACS |
Q&T | Heavy plate for thick booms and base frames; slightly lower guaranteed strength due to reduced quench rate. | 710 | 810 | 16 | 24 HRC | 7.2 % IACS |
QTDefault Quenched and tempered | Standard stocked condition for crane booms and machinery frames up to 50 mm plate. | 750 | 830 | 16 | 26 HRC | 7.2 % IACS |
Quality class C | Cheapest quality class for indoor or mild-climate structures with no low-temperature toughness demand. | 750 | 830 | 16 | 26 HRC | 7.2 % IACS |
Quality class D | Most common Chinese stock class for mobile cranes and pump-truck booms. | 750 | 830 | 16 | 26 HRC | 7.2 % IACS |
Quality class E | Cold-climate equipment (northern China, mining, offshore support); equivalent to S690QL. | 750 | 830 | 16 | 26 HRC | 7.2 % IACS |
Quality class F | Extreme low-temperature / arctic service; equivalent to S690QL1, mill order only. | 750 | 830 | 17 | 26 HRC | 7.2 % IACS |
Supply forms, finishes and certifications
Ways Q690Q is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
Z35 | Through-thickness (Z-quality) tested plate | Certification |
What is Q690Q?
Q690Q is a quenched and tempered high-strength structural plate to GB/T 16270, equivalent to EN S690Q, with 750 MPa yield, 830 MPa tensile, 16% elongation and about 260 HB (26 HRC). It serves cranes and heavy machinery as plate in thickness-banded QT conditions (50–100 mm, 100–150 mm), impact classes Q690C to Q690F and Z35 through-thickness quality. It machines, bends and welds more easily than the 890 and 960 grades, but still needs low-hydrogen consumables, preheat and painting, and must not be heat treated above its tempering temperature. Q890Q is the next strength step. Q690Q has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F). Q690Q has a yield strength of 750 MPa (109 ksi) and a tensile strength of 830 MPa (120 ksi) — stronger than 84% of steel grades. Elongation at break is 16% and the elastic modulus is 210 GPa (30.5 Msi).
What is Q690Q used for?
- cranes
- excavator structures
- heavy trailers
Advantages
- High strength — 750 MPa (109 ksi), better than 84% of steel grades
Q690Q properties
Typical room-temperature values for Q690Q-QT; bars are the position among steel grades.
Physical3
Q690Q has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F).
Mechanical16
Q690Q has a yield strength of 750 MPa (109 ksi) and a tensile strength of 830 MPa (120 ksi) — stronger than 84% of steel grades. Elongation at break is 16% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
Q690Q is rated for continuous service to 350°C (662 °F). It conducts heat at 38 W/m·K (22 BTU/hr·ft·°F), worse than 69% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
Q690Q conducts electricity at 7.2 % IACS, worse than 71% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (14/100), better than 70% of steel grades.
Sustainability4
Producing a kilogram of Q690Q takes about 30 MJ of energy and emits 2.3 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 22%.
Manufacturability7
Q690Q's machinability is fair (42/100, worse than 73% of steel grades); weldability good (62/100); formability fair (45/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the steel family
Yield strength against density for every steel grade FabDigit runs. Q690Q is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Q690Q
Is Q690Q easy to machine?
Machine as ~260 HB Q&T alloy steel: rigid setups, coated carbide, moderate speeds; avoid heavy grinding heat that tempers the surface.
Can Q690Q be welded?
Low-hydrogen consumables matched to 690 MPa, preheat ~100–150 °C (CEV ≈0.55–0.65), control interpass ≤200 °C and heat input ≤2.0 kJ/mm to protect HAZ toughness; no post-weld heat treatment above the tempering temperature.
Can Q690Q be formed, bent or molded?
Cold bend transverse to rolling direction with min inner radius ≈3t (thin) to 4–5t (thick); allow for large springback and deburr flame-cut edges before bending.
Q690Q chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| C≤0.20 for t≤50 mm | ≤ 0.2 | 0.16 |
| Si | ≤ 0.8 | 0.3 |
| Mn | ≤ 1.7 | 1.3 |
| P≤0.020 for E/F classes | ≤ 0.03 | 0.01 |
| S≤0.010 for E/F classes | ≤ 0.02 | 0.01 |
| Cr | ≤ 1.5 | 0.5 |
| Ni | ≤ 2 | 0.6 |
| Mo | ≤ 0.7 | 0.35 |
| Cu | ≤ 0.5 | 0.15 |
| V | ≤ 0.12 | 0.04 |
| Nb | ≤ 0.06 | 0.03 |
| Ti | ≤ 0.05 | 0.02 |
| B | ≤ 0.01 | 0 |
| Altotal Al, grain refining | ≥ 0.02 | 0.03 |
| N | ≤ 0.02 | 0.01 |
| Fe | balance |
What surface finishes work on Q690Q?
Shot blast and paint or zinc-rich primer; hot-dip galvanizing possible but screen for liquid-metal embrittlement and residual stress.
Surface treatments FabDigit runs on steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Organic Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel Q690Q in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- EN / DIN / Werkstoff-Nr.
- S690Q
How much does Q690Q cost?
Q690Q is a budget-cost steel ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Q690Q — frequently asked
What is Q690Q used for?
Q690Q is typically used for cranes, excavator structures and heavy trailers. In short: entry-level high-strength Q&T; best weldability in family; S690Q equivalent.
What is the yield strength of Q690Q?
Q690Q has a typical yield strength of 750 MPa (109 ksi) and a tensile strength of 830 MPa (120 ksi) — stronger than 84% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is Q690Q easy to machine?
Not especially — machinability is rated fair (42/100, worse than 73% of steel grades). Machine as ~260 HB Q&T alloy steel: rigid setups, coated carbide, moderate speeds; avoid heavy grinding heat that tempers the surface.
Can Q690Q be welded?
Yes — weldability is rated good (62/100). Low-hydrogen consumables matched to 690 MPa, preheat ~100–150 °C (CEV ≈0.55–0.65), control interpass ≤200 °C and heat input ≤2.0 kJ/mm to protect HAZ toughness; no post-weld heat treatment above the tempering temperature.
What surface finishes work on Q690Q?
Shot blast and paint or zinc-rich primer; hot-dip galvanizing possible but screen for liquid-metal embrittlement and residual stress.
Can Q690Q be formed, bent or molded?
Cold bend transverse to rolling direction with min inner radius ≈3t (thin) to 4–5t (thick); allow for large springback and deburr flame-cut edges before bending.
What is the maximum service temperature of Q690Q?
Q690Q is rated for continuous use to about 350°C (662 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between Q690Q-QT and Q690Q-Q690C?
QT is the default condition — standard stocked condition for crane booms and machinery frames up to 50 mm plate. Q690C: cheapest quality class for indoor or mild-climate structures with no low-temperature toughness demand. Yield strength is 750 MPa in QT versus 750 MPa in Q690C.
How much does Q690Q cost?
Q690Q is a budget-cost steel ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- EN 10025-6 Hot rolled products of structural steels — Flat products of high yield strength structural steels in the quenched and tempered condition — CEN (2019)
- S690QL / high-strength Q&T plate datasheet and welding recommendations — SSAB / Dillinger / (2023)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.19 — Fatigue and Fracture — ASM International (1996)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.