Steel S690QL
EN S690QL
S690QL is a water-quenched and tempered fine-grained structural steel to EN 10025-6 with a minimum yield strength of 690 MPa and guaranteed Charpy V-notch toughness at −40 °C (the 'L' quality).
Values for the Q&T condition
S690QL tempers and conditions
S690QL is supplied in 4 conditions, soft to hard. Q&T is the default FabDigit quotes; the values on this page are for it.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Q&T | Thickest standard supply range; lowest guaranteed properties, used for very heavy machined structural blocks. | 700 | 790 | 16 | 24 HRC | 7.2 % IACS |
Q&T | Heavy plate; guaranteed yield drops to 650 MPa because of slower quench through-thickness. | 720 | 810 | 16 | 25 HRC | 7.2 % IACS |
Q&T + stress relieved | Ordered when welded or heavily machined assemblies must be dimensionally stable; hold below the tempering temperature or strength drops. | 720 | 805 | 17 | 25 HRC | 7.2 % IACS |
Q&TDefault Quenched and tempered | Standard as-delivered plate condition; full 690 MPa minimum yield — pick for normal boom, chassis and lifting-structure plate. | 760 | 830 | 16 | 27 HRC | 7.2 % IACS |
What is S690QL?
S690QL is a water-quenched and tempered fine-grained structural steel to EN 10025-6 with a minimum yield strength of 690 MPa and guaranteed Charpy V-notch toughness at −40 °C (the 'L' quality). Its low carbon equivalent and Ni-Cr-Mo-B micro-alloying give a fine martensitic/bainitic structure that combines very high strength with good weldability and cold formability, which is why it dominates mobile crane booms, tipper bodies, concrete pumps and heavy load-bearing plate structures. Limits: strength is heat-treatment derived, so heat input, preheat and any post-weld heat treatment must be controlled (softening above ~580 °C), it has no inherent corrosion resistance, and section thickness above 50 mm reduces the guaranteed yield level. S690QL has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,440°C (2,624 °F). S690QL has a yield strength of 760 MPa (110 ksi) and a tensile strength of 830 MPa (120 ksi) — stronger than 85% of steel grades. Elongation at break is 16% and the elastic modulus is 210 GPa (30.5 Msi).
What is S690QL used for?
- Mobile crane booms
- Tipper and dump bodies
- Concrete pump booms
- Mining equipment structures
- Excavator arms and buckets
- Trailer and chassis frames
- Lifting lugs and heavy load-bearing plate
Advantages
- High strength — 760 MPa (110 ksi), better than 85% of steel grades
- Tough — resists crack growth — 120 MPa·√m (109.2 ksi·√in), better than 81% of steel grades
Limitations
- High embodied carbon — 2.5 kg CO₂/kg, worse than 82% of steel grades
- Difficult to machine — 40/100, worse than 77% of steel grades
- Poor heat conductor — 35 W/m·K (20.2 BTU/hr·ft·°F), worse than 75% of steel grades
S690QL properties
Typical room-temperature values for S690QL-Q&T; bars are the position among steel grades.
Physical3
S690QL has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,440°C (2,624 °F).
Mechanical16
S690QL has a yield strength of 760 MPa (110 ksi) and a tensile strength of 830 MPa (120 ksi) — stronger than 85% of steel grades. Elongation at break is 16% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
S690QL is rated for continuous service to 350°C (662 °F). It conducts heat at 35 W/m·K (20.2 BTU/hr·ft·°F), worse than 75% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
S690QL 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 S690QL takes about 32 MJ of energy and emits 2.5 kg of CO₂ — more than 70% of steel grades. Typical recycled content is 30%.
Manufacturability6
S690QL's machinability is fair (40/100, worse than 77% of steel grades); weldability good (65/100); 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. S690QL is highlighted; hover a dot for its name, or open the interactive family chart.
Working with S690QL
Is S690QL easy to machine?
Machines like a ~270 HB Q&T alloy steel: rigid setups, coated carbide, moderate speeds and positive feeds; expect springback-free but tool-wearing chips and relieve stresses before finish machining thick sections.
Can S690QL be welded?
Good weldability with low-hydrogen consumables matching ~690 MPa; control preheat/interpass (typically 100–150 °C for thick or restrained joints), limit heat input to protect HAZ toughness, and keep hydrogen out to avoid cold cracking.
Can S690QL be formed, bent or molded?
Cold bendable with inner radius roughly 3–4× thickness transverse to rolling direction; grind-smooth burr-free edges before bending and avoid hot forming above the tempering temperature.
Manufacturability
The process limits FabDigit applies to S690QL. Every S690QL part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
CNC machining
| Machinability | Better40 / 100 |
|---|---|
| ISO material group | P.2 |
| Cutting speed (rough / finish) | 180 / 210 m/min |
| Minimum wall | 0.8 mm |
| Minimum internal radius | 1 mm |
| Drill depth limit | 5× diameter |
| Best surface (machined / polished) | Ra 1.6 / — |
| Hardenable after machining | No |
Sheet metal
| Formability | Fair45 / 100 |
|---|---|
| Weldability | Better65 / 100 |
| Bendable | Yes |
S690QL 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 |
|---|---|---|
| Cmax for t ≤ 50 mm | ≤ 0.2 | 0.16 |
| Si | ≤ 0.8 | 0.3 |
| Mn | ≤ 1.7 | 1.3 |
| P | ≤ 0.03 | 0.01 |
| S | ≤ 0.01 | 0 |
| N | ≤ 0.02 | 0.01 |
| Cr | ≤ 1.5 | 0.5 |
| Ni | ≤ 2 | 0.6 |
| Mo | ≤ 0.7 | 0.4 |
| Cu | ≤ 0.5 | 0.15 |
| V | ≤ 0.12 | 0.05 |
| Nb | ≤ 0.06 | 0.02 |
| Ti | ≤ 0.05 | 0.02 |
| Zr | ≤ 0.05 | |
| B | ≤ 0.01 | 0 |
| Altotal Al, minimum | ≥ 0.02 | 0.03 |
| Fe | balance |
What surface finishes work on S690QL?
No self-protection — blast, then paint, zinc-rich primer or metallize; hot-dip galvanizing is possible but assess liquid-metal-assisted cracking risk at this strength level.
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).
Plating
CVD Coating
Black / Phosphate
Thermal Spray
How much does S690QL cost?
S690QL is a standard-cost steel ($$), cheaper than about 61% 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.
S690QL — frequently asked
What is S690QL used for?
S690QL is typically used for mobile crane booms, tipper and dump bodies, concrete pump booms, mining equipment structures, excavator arms and buckets and trailer and chassis frames. In short: high-strength Q&T plate.
What is the yield strength of S690QL?
S690QL has a typical yield strength of 760 MPa (110 ksi) and a tensile strength of 830 MPa (120 ksi) — stronger than 85% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is S690QL easy to machine?
Not especially — machinability is rated fair (40/100, worse than 77% of steel grades). Machines like a ~270 HB Q&T alloy steel: rigid setups, coated carbide, moderate speeds and positive feeds; expect springback-free but tool-wearing chips and relieve stresses before finish machining thick sections.
Can S690QL be welded?
Yes — weldability is rated good (65/100). Good weldability with low-hydrogen consumables matching ~690 MPa; control preheat/interpass (typically 100–150 °C for thick or restrained joints), limit heat input to protect HAZ toughness, and keep hydrogen out to avoid cold cracking.
What surface finishes work on S690QL?
No self-protection — blast, then paint, zinc-rich primer or metallize; hot-dip galvanizing is possible but assess liquid-metal-assisted cracking risk at this strength level.
Can S690QL be formed, bent or molded?
Cold bendable with inner radius roughly 3–4× thickness transverse to rolling direction; grind-smooth burr-free edges before bending and avoid hot forming above the tempering temperature.
What is the maximum service temperature of S690QL?
S690QL 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.
How much does S690QL cost?
S690QL is a standard-cost steel ($$), cheaper than about 61% 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.
Can FabDigit make parts in S690QL?
Yes — S690QL is available for CNC machining and sheet metal; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.
Sources
- EN 10025-6 Hot rolled products of structural steels — Part 6: flat products of high yield strength structural steels in the quenched and tempered condition — CEN (2019)
- Strenx 700 / Weldox 700 structural plate data — SSAB (2023)
- DILLIMAX 690 high-strength quenched and tempered steel plate — Dillinger (2022)
- 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)
- GB/T 16270 (Q690D/E equivalent) — SAC (2009)
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.