Steel Q890Q-QL1
Heat-treated state
GB Q890Q · EN S890Q
QL1 = q&T, extra-low-temperature impact class
Highest toughness class of the family, for arctic service and critical fracture-controlled joints.
Values for the QL1 condition
Other Q890Q tempers and conditions
Q890Q is listed in 5 conditions; see the grade overview at Q890Q.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Q&T heavy plate | Thick-section plate; lower guaranteed yield due to reduced through-thickness quench severity. | 880 | 950 | 14 | 31 HRC | 7 % IACS |
Stress relieved | Used after heavy welding or machining of thick weldments; slightly lowers strength. | 910 | 970 | 15 | 32 HRC | 7 % IACS |
QTDefault Quenched and tempered | Standard stocked condition for crane booms and machinery structures in normal climates. | 950 | 1,000 | 14 | 34 HRC | 7 % IACS |
Q&T, low-temperature impact class | Choose for cold-climate cranes and offshore-adjacent structures needing −40 °C toughness. | 950 | 1,000 | 14 | 34 HRC | 7 % IACS |
QL1This page Q&T, extra-low-temperature impact class | Highest toughness class of the family, for arctic service and critical fracture-controlled joints. | 950 | 1,000 | 15 | 33 HRC | 7 % IACS |
What is Q890Q-QL1?
Q890Q-QL1 is Q890Q heat treated to QL1 — highest toughness class of the family, for arctic service and critical fracture-controlled joints. Q890Q-QL1 has a yield strength of 950 MPa (138 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 91% of steel grades. Elongation at break is 15% and the elastic modulus is 210 GPa (30.5 Msi). Q890Q-QL1 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; QL1 is available on request or by drawing note.
Advantages
- High strength — 950 MPa (138 ksi), better than 91% of steel grades
- Tough — resists crack growth — 120 MPa·√m (109.2 ksi·√in), better than 81% of steel grades
Limitations
- Difficult to machine — 34/100, worse than 86% of steel grades
- Poor heat conductor — 35 W/m·K (20.2 BTU/hr·ft·°F), worse than 75% of steel grades
Q890Q-QL1 properties
Typical room-temperature values for Q890Q-QL1; 23 are specific to this condition. Other listed values are Q890Q reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
Q890Q-QL1 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
Q890Q-QL1 has a yield strength of 950 MPa (138 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 91% of steel grades. Elongation at break is 15% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
Q890Q-QL1 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
Q890Q-QL1 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 Q890Q-QL1 takes about 31 MJ of energy and emits 2.3 kg of CO₂ — more than 64% of steel grades. Typical recycled content is 25%.
Manufacturability8
Q890Q-QL1's machinability is poor (34/100, worse than 86% of steel grades); weldability good (62/100); formability fair (37/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Q890Q-QL1
Is Q890Q easy to machine?
Machine like 320 HB Q&T alloy steel: rigid setups, coated carbide, moderate speeds (~80–120 m/min) with generous feed and coolant; avoid rubbing that work-hardens the surface.
Can Q890Q be welded?
Weldable with low-hydrogen SMAW/MAG/SAW using matching or slightly undermatching consumables; preheat typically 100–175 °C by thickness/CEV, interpass ≤200 °C, control heat input (≈1.0–2.5 kJ/mm) to protect HAZ toughness — no post-weld normalizing.
Can Q890Q be formed, bent or molded?
Cold bendable with punch radius ≥3–4× thickness transverse to rolling direction; deburr and grind flame-cut edges before bending, hot forming above the tempering temperature destroys the Q&T properties.
What surface finishes work on Q890Q?
Shot-blast to Sa 2½ and apply zinc-rich epoxy primer or metallizing; hot-dip galvanizing and electroplating are risky due to hydrogen embrittlement at this strength level.
Q890Q 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 |
|---|---|---|
| Cladle analysis | ≤ 0.2 | 0.16 |
| Si | ≤ 0.8 | 0.3 |
| Mn | ≤ 1.7 | 1.2 |
| P | ≤ 0.03 | 0.01 |
| S | ≤ 0.01 | 0 |
| Cr | ≤ 1.5 | 0.6 |
| Ni | ≤ 2 | 0.8 |
| Mo | ≤ 0.7 | 0.4 |
| Cu | ≤ 0.5 | 0.15 |
| V | ≤ 0.12 | 0.04 |
| Nb | ≤ 0.06 | 0.03 |
| Ti | ≤ 0.05 | 0.02 |
| Bhardenability booster | ≤ 0.01 | 0 |
| Zr | ≤ 0.05 | — |
| N | ≤ 0.02 | 0.01 |
| Altotal Al, or other N-binding element | ≥ 0.02 | 0.03 |
| Fe | balance | — |
Q890Q-QL1 — frequently asked
What is Q890Q-QL1 used for?
Q890Q-QL1 is typically used for crane booms, structural fabrications and heavy machinery. In short: mid-range 890 MPa Q&T; S890Q equivalent; QL and QL1 toughness options.
What is the yield strength of Q890Q-QL1?
Q890Q-QL1 has a typical yield strength of 950 MPa (138 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 91% of steel grades. Strength varies by condition: see the 5 listed tempers.
Is Q890Q-QL1 easy to machine?
Not especially — machinability is rated poor (34/100, worse than 86% of steel grades). Machine like 320 HB Q&T alloy steel: rigid setups, coated carbide, moderate speeds (~80–120 m/min) with generous feed and coolant; avoid rubbing that work-hardens the surface.
Can Q890Q-QL1 be welded?
Yes — weldability is rated good (62/100). Weldable with low-hydrogen SMAW/MAG/SAW using matching or slightly undermatching consumables; preheat typically 100–175 °C by thickness/CEV, interpass ≤200 °C, control heat input (≈1.0–2.5 kJ/mm) to protect HAZ toughness — no post-weld normalizing.
What surface finishes work on Q890Q-QL1?
Shot-blast to Sa 2½ and apply zinc-rich epoxy primer or metallizing; hot-dip galvanizing and electroplating are risky due to hydrogen embrittlement at this strength level.
Can Q890Q-QL1 be formed, bent or molded?
Cold bendable with punch radius ≥3–4× thickness transverse to rolling direction; deburr and grind flame-cut edges before bending, hot forming above the tempering temperature destroys the Q&T properties.
What is the maximum service temperature of Q890Q-QL1?
Q890Q-QL1 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 Q890Q-QT and Q890Q-SR?
QT is the default condition — standard stocked condition for crane booms and machinery structures in normal climates. SR: used after heavy welding or machining of thick weldments; slightly lowers strength. Yield strength is 950 MPa in QT versus 910 MPa in SR.
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)
- High-strength quenched & tempered structural plate (S890Q class) data sheets — SSAB / Dillinger / Baosteel (2023)
- 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.