Steel GX9Ni5 +QT (Quenched and tempered)
Heat-treated state · default condition
EN 1.5681
Standard delivery condition for pressure castings needing guaranteed KV ≥ 27 J at -100 °C.
Values for the +QT condition
Other GX9Ni5 tempers and conditions
GX9Ni5 is listed in 3 conditions; see the grade overview at GX9Ni5.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Interim foundry condition for rough machining or weld repair; final +QT/+NT treatment is required before service. | 310 | 490 | 27 | 150 HB | 5.3 % IACS |
Normalized and tempered | Chosen for thick or complex castings where quenching risks distortion/cracking; slightly lower strength than +QT. | 370 | 540 | 25 | 165 HB | 5.2 % IACS |
+QTDefaultThis page Quenched and tempered | Standard delivery condition for pressure castings needing guaranteed KV ≥ 27 J at -100 °C. | 400 | 570 | 24 | 175 HB | 5.2 % IACS |
What is GX9Ni5 +QT?
GX9Ni5 +QT is GX9Ni5 heat treated to +QT — standard delivery condition for pressure castings needing guaranteed KV ≥ 27 J at -100 °C. GX9Ni5 +QT has a yield strength of 400 MPa (58 ksi) and a tensile strength of 570 MPa (82.7 ksi) — weaker than 60% of steel grades. Elongation at break is 24% and the elastic modulus is 205 GPa (29.7 Msi). GX9Ni5 +QT 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).
Advantages
- Tough — resists crack growth — 130 MPa·√m (118.3 ksi·√in), better than 89% of steel grades
Limitations
- High embodied carbon — 2.6 kg CO₂/kg, worse than 87% of steel grades
- Low electrical conductivity — 5.2 % IACS, worse than 81% of steel grades
- Poor heat conductor — 33 W/m·K (19.1 BTU/hr·ft·°F), worse than 80% of steel grades
- Limited formability — 20/100, worse than 80% of steel grades
GX9Ni5 +QT properties
Typical room-temperature values for GX9Ni5 +QT; 23 are specific to this condition. Other listed values are GX9Ni5 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
GX9Ni5 +QT 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
GX9Ni5 +QT has a yield strength of 400 MPa (58 ksi) and a tensile strength of 570 MPa (82.7 ksi) — weaker than 60% of steel grades. Elongation at break is 24% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
GX9Ni5 +QT is rated for continuous service to 350°C (662 °F). It conducts heat at 33 W/m·K (19.1 BTU/hr·ft·°F), worse than 80% of steel grades. Thermal expansion is 11.5 µm/m·K (6.39 µin/in·°F).
Electrical3
GX9Ni5 +QT conducts electricity at 5.2 % IACS, worse than 81% of steel grades.
Chemical & Environmental2
Corrosion resistance is poor (17/100), better than 81% of steel grades.
Sustainability4
Producing a kilogram of GX9Ni5 +QT takes about 34 MJ of energy and emits 2.6 kg of CO₂ — more than 82% of steel grades. Typical recycled content is 65%.
Manufacturability8
GX9Ni5 +QT's machinability is fair (50/100, worse than 53% of steel grades); weldability good (65/100); formability poor (20/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with GX9Ni5 +QT
Is GX9Ni5 easy to machine?
Tough, work-hardening Ni steel — use rigid setups, sharp positive-rake carbide, moderate speed with heavy feed; leave stock for finish cuts after final heat treatment.
Can GX9Ni5 be welded?
Readily welded with low-hydrogen 2.5–5 Ni or Ni-base consumables; preheat ~100–150 °C, limit interpass, and re-temper (PWHT) weld-repaired castings.
Can GX9Ni5 be formed, bent or molded?
Supplied as sand/investment casting — control feeding and use risers/chills for sound heavy sections; hot straightening should be followed by re-heat treatment.
What surface finishes work on GX9Ni5?
No anodizing; protect with shot blast plus epoxy paint, zinc/aluminium metallizing, or electroless nickel for cryogenic service exteriors.
GX9Ni5 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 |
|---|---|---|
| Clow carbon for toughness and weldability | ≤ 0.1 | 0.08 |
| Si | ≤ 0.6 | 0.4 |
| Mn | 0.5 – 0.8 | 0.65 |
| P | ≤ 0.02 | 0.01 |
| S | ≤ 0.02 | 0.01 |
| Niprovides low-temperature toughness | 4 – 5 | 4.7 |
| Crresidual | ≤ 0.3 | 0.1 |
| Moresidual | ≤ 0.2 | 0.05 |
| Curesidual | ≤ 0.3 | 0.1 |
| Vresidual | ≤ 0.05 | 0.02 |
| Fe | balance | — |
GX9Ni5 +QT — frequently asked
What is GX9Ni5 +QT used for?
GX9Ni5 +QT is typically used for low-temperature pump and valve castings, pressure equipment components and offshore equipment castings. In short: 5 % Ni cast steel; low-temperature toughness; readily weldable casting.
What is the yield strength of GX9Ni5 +QT?
GX9Ni5 +QT has a typical yield strength of 400 MPa (58 ksi) and a tensile strength of 570 MPa (82.7 ksi) — weaker than 60% of steel grades. Strength varies by condition: see the 3 listed tempers.
Is GX9Ni5 +QT easy to machine?
Reasonably — machinability is rated fair (50/100, worse than 53% of steel grades). Tough, work-hardening Ni steel — use rigid setups, sharp positive-rake carbide, moderate speed with heavy feed; leave stock for finish cuts after final heat treatment.
Can GX9Ni5 +QT be welded?
Yes — weldability is rated good (65/100). Readily welded with low-hydrogen 2.5–5 Ni or Ni-base consumables; preheat ~100–150 °C, limit interpass, and re-temper (PWHT) weld-repaired castings.
What surface finishes work on GX9Ni5 +QT?
No anodizing; protect with shot blast plus epoxy paint, zinc/aluminium metallizing, or electroless nickel for cryogenic service exteriors.
Can GX9Ni5 +QT be formed, bent or molded?
Supplied as sand/investment casting — control feeding and use risers/chills for sound heavy sections; hot straightening should be followed by re-heat treatment.
What is the maximum service temperature of GX9Ni5 +QT?
GX9Ni5 +QT 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.
Sources
- EN 10213 — Steel castings for pressure purposes (low-temperature grades) — CEN (2016)
- ASTM A352/A352M — Ferritic and martensitic steel castings for low-temperature service — ASTM (2018)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- Steel Castings Handbook — Steel Founders' Society of America / ASM (1995)
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.