Steel S690QL Q&T+SR
Heat-treated state
EN S690QL
Q&T+SR = q&T + stress relieved
Ordered when welded or heavily machined assemblies must be dimensionally stable; hold below the tempering temperature or strength drops.
Values for the Q&T+SR condition
Other S690QL tempers and conditions
S690QL is listed in 4 conditions; see the grade overview at S690QL.
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+SRThis page 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 Q&T+SR?
S690QL Q&T+SR is S690QL heat treated to Q&T+SR — ordered when welded or heavily machined assemblies must be dimensionally stable; hold below the tempering temperature or strength drops. S690QL Q&T+SR has a yield strength of 720 MPa (104 ksi) and a tensile strength of 805 MPa (117 ksi) — stronger than 82% of steel grades. Elongation at break is 17% and the elastic modulus is 210 GPa (30.5 Msi). S690QL Q&T+SR 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). Q&T is the default condition FabDigit quotes; Q&T+SR is available on request or by drawing note.
Advantages
- Tough — resists crack growth — 125 MPa·√m (113.8 ksi·√in), better than 85% of steel grades
- High strength — 720 MPa (104 ksi), better than 82% of steel grades
Limitations
- High embodied carbon — 2.5 kg CO₂/kg, worse than 82% of steel grades
- Poor heat conductor — 35 W/m·K (20.2 BTU/hr·ft·°F), worse than 75% of steel grades
S690QL Q&T+SR properties
Typical room-temperature values for S690QL Q&T+SR; 22 are specific to this condition. Other listed values are S690QL reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
S690QL Q&T+SR 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 Q&T+SR has a yield strength of 720 MPa (104 ksi) and a tensile strength of 805 MPa (117 ksi) — stronger than 82% of steel grades. Elongation at break is 17% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
S690QL Q&T+SR is rated for continuous service to 380°C (716 °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 Q&T+SR 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 Q&T+SR 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 Q&T+SR's machinability is fair (43/100, worse than 71% of steel grades); weldability good (68/100); formability fair (48/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with S690QL Q&T+SR
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.
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.
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 | — |
S690QL Q&T+SR — frequently asked
What is S690QL Q&T+SR used for?
S690QL Q&T+SR 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 Q&T+SR?
S690QL Q&T+SR has a typical yield strength of 720 MPa (104 ksi) and a tensile strength of 805 MPa (117 ksi) — stronger than 82% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is S690QL Q&T+SR easy to machine?
Not especially — machinability is rated fair (43/100, worse than 71% 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 Q&T+SR be welded?
Yes — weldability is rated good (68/100). 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 Q&T+SR?
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 Q&T+SR 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 Q&T+SR?
S690QL Q&T+SR is rated for continuous use to about 380°C (716 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in S690QL Q&T+SR?
Yes — S690QL Q&T+SR 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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.