Steel Q960Q QT+SR
Heat-treated state
GB Q960Q · EN S960Q
Specify after welding or cold forming when residual stress and distortion must be controlled; stress relief below the original tempering temperature trades yield down to 950 MPa for higher toughness.
Values for the QT+SR condition
Other Q960Q tempers and conditions
Q960Q is listed in 3 conditions; see the grade overview at Q960Q.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
QT+SRThis page quenched, tempered and stress-relieved (≤ 580 °C) | Specify after welding or cold forming when residual stress and distortion must be controlled; stress relief below the original tempering temperature trades yield down to 950 MPa for higher toughness. | 950 | 1,010 | 14 | 34 HRC | 7 % IACS |
QT | Use for thick-walled welded structures and large frames from 50 to 80 mm, where limited hardenability lowers core yield to 975 MPa, elongation to 12% and weldability to score 45. | 975 | 1,020 | 12 | 35 HRC | 7 % IACS |
QTDefault Quenched and tempered | Pick this quenched and tempered plate up to 50 mm thickness for booms, lifting arms and other lightweight load-bearing parts needing 1010 MPa yield at 13% elongation. | 1,010 | 1,050 | 13 | 36 HRC | — |
What is Q960Q QT+SR?
Q960Q QT+SR is Q960Q heat treated to QT+SR — specify after welding or cold forming when residual stress and distortion must be controlled; stress relief below the original tempering temperature trades yield down to 950 MPa for higher toughness. Q960Q QT+SR has a yield strength of 950 MPa (138 ksi) and a tensile strength of 1,010 MPa (146 ksi) — stronger than 91% of steel grades. Elongation at break is 14% and the elastic modulus is 210 GPa (30.5 Msi). Q960Q QT+SR has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,420°C (2,588 °F). QT is the default condition FabDigit quotes; QT+SR is available on request or by drawing note.
Advantages
- High strength — 950 MPa (138 ksi), better than 91% of steel grades
Limitations
- Difficult to machine — 33/100, worse than 86% of steel grades
- Limited service temperature — 250°C (482 °F), worse than 85% of steel grades
- Poor heat conductor — 34 W/m·K (19.6 BTU/hr·ft·°F), worse than 77% of steel grades
- Limited ductility — 14%, worse than 75% of steel grades
Q960Q QT+SR properties
Typical room-temperature values for Q960Q QT+SR; 22 are specific to this condition. Other listed values are Q960Q reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
Q960Q QT+SR has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical16
Q960Q QT+SR has a yield strength of 950 MPa (138 ksi) and a tensile strength of 1,010 MPa (146 ksi) — stronger than 91% of steel grades. Elongation at break is 14% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
Q960Q QT+SR is rated for continuous service to 250°C (482 °F). It conducts heat at 34 W/m·K (19.6 BTU/hr·ft·°F), worse than 77% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
Q960Q QT+SR conducts electricity at 7 % IACS, worse than 74% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of Q960Q QT+SR takes about 30 MJ of energy and emits 2.4 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 25%.
Manufacturability6
Q960Q QT+SR's machinability is poor (33/100, worse than 86% of steel grades); weldability fair (53/100); formability poor (34/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Q960Q QT+SR
Is Q960Q easy to machine?
Use coated carbide tooling with low cutting speed, heavy feed and rigid clamping; at 320–370 HB cutting forces are high and the surface work-hardens easily. Drill on high-rigidity machines with ample coolant.
Can Q960Q be welded?
Weldable with low-hydrogen consumables of the ≥890 MPa class, preheat 100–150 °C (higher for thick plate), interpass ≤200 °C and controlled heat input to avoid HAZ softening and cold cracking. Do not re-quench after welding.
Can Q960Q be formed, bent or molded?
Cold bend transverse to the rolling direction with a minimum bend radius of about 3–4t and increased die clearance. Hot forming destroys the quench-and-temper properties and requires re-quenching and tempering.
What surface finishes work on Q960Q?
Painting, zinc spraying or hot-dip galvanizing is required for corrosion protection. Galvanizing and acid pickling carry a hydrogen embrittlement risk and need a de-embrittlement bake; shot peening improves fatigue life.
Q960Q 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 |
|---|---|---|
| Cupper limit, heat analysis | ≤ 0.2 | 0.17 |
| Si | ≤ 0.8 | 0.35 |
| Mn | ≤ 1.7 | 1.3 |
| P | ≤ 0.03 | 0.01 |
| S | ≤ 0.01 | 0 |
| Cr | ≤ 1.5 | 0.6 |
| Ni | ≤ 2 | 1 |
| Mo | ≤ 0.7 | 0.45 |
| Cu | ≤ 0.5 | 0.15 |
| V | ≤ 0.12 | 0.05 |
| Nb | ≤ 0.06 | 0.03 |
| Ti | ≤ 0.05 | 0.02 |
| Bimproves hardenability | ≤ 0.01 | 0 |
| Altotal Al, refines grain | ≥ 0.02 | 0.03 |
| N | ≤ 0.02 | 0.01 |
| Zr | ≤ 0.15 | — |
| Fe | balance | — |
Q960Q QT+SR — frequently asked
What is Q960Q QT+SR used for?
Q960Q QT+SR is typically used for mobile crane telescopic sections, ultra-high-strength trailer frames, boom arms for lifting equipment, chassis crossmembers for heavy transport, load-bearing structural weldments and lightweight lifting attachments. In short: top standard GB Q&T grade; S960Q equivalent; weight-critical booms.
What is the yield strength of Q960Q QT+SR?
Q960Q QT+SR has a typical yield strength of 950 MPa (138 ksi) and a tensile strength of 1,010 MPa (146 ksi) — stronger than 91% of steel grades. Strength varies by condition: see the 3 listed tempers.
Is Q960Q QT+SR easy to machine?
Not especially — machinability is rated poor (33/100, worse than 86% of steel grades). Use coated carbide tooling with low cutting speed, heavy feed and rigid clamping; at 320–370 HB cutting forces are high and the surface work-hardens easily. Drill on high-rigidity machines with ample coolant.
Can Q960Q QT+SR be welded?
With care — weldability is rated fair (53/100). Weldable with low-hydrogen consumables of the ≥890 MPa class, preheat 100–150 °C (higher for thick plate), interpass ≤200 °C and controlled heat input to avoid HAZ softening and cold cracking. Do not re-quench after welding.
What surface finishes work on Q960Q QT+SR?
Painting, zinc spraying or hot-dip galvanizing is required for corrosion protection. Galvanizing and acid pickling carry a hydrogen embrittlement risk and need a de-embrittlement bake; shot peening improves fatigue life.
Can Q960Q QT+SR be formed, bent or molded?
Cold bend transverse to the rolling direction with a minimum bend radius of about 3–4t and increased die clearance. Hot forming destroys the quench-and-temper properties and requires re-quenching and tempering.
What is the maximum service temperature of Q960Q QT+SR?
Q960Q QT+SR is rated for continuous use to about 250°C (482 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
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)
- ASM Handbook Vol.1: Properties and Selection — Irons, Steels, and High-Performance Alloys — ASM International (1990)
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.