Steel G20NiMoCr4 +QT (Quenched and tempered)
Heat-treated state · default condition
EN 1.6750
Standard supply condition: best combination of ≈400–500 MPa yield with high sub-zero notch toughness in heavy sections.
Values for the +QT condition
Other G20NiMoCr4 tempers and conditions
G20NiMoCr4 is listed in 7 conditions; see the grade overview at G20NiMoCr4.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Choose for rough machining of large castings before the final quench-and-temper cycle. | 330 | 560 | 24 | 165 HB | 7.9 % IACS |
Normalized | Grain-refining treatment used as an intermediate step or for lightly loaded castings. | 400 | 630 | 18 | 190 HB | 7.8 % IACS |
As fabricated | Raw foundry state before heat treatment; not a delivery condition for pressure parts — coarse, segregated structure with poor toughness. | 420 | 700 | 10 | 17 HRC | 7.8 % IACS |
Normalized and tempered | Economical delivery condition for thick castings where full quench penetration is impractical; slightly lower strength than +QT. | 420 | 620 | 20 | 185 HB | 7.8 % IACS |
Quenched, tempered and stress-relieved after weld repair | Used after foundry weld repair or heavy machining of pressure castings to restore dimensional stability and HAZ toughness. | 445 | 640 | 19 | 195 HB | 7.8 % IACS |
+QTDefaultThis page Quenched and tempered | Standard supply condition: best combination of ≈400–500 MPa yield with high sub-zero notch toughness in heavy sections. | 460 | 660 | 18 | 200 HB | — |
Quenched and tempered, high-strength class | Pick where ≥550 MPa yield is needed in thinner sections and some toughness margin can be traded away. | 600 | 800 | 14 | 24 HRC | — |
What is G20NiMoCr4 +QT?
G20NiMoCr4 +QT is G20NiMoCr4 heat treated to +QT — standard supply condition: best combination of ≈400–500 MPa yield with high sub-zero notch toughness in heavy sections. G20NiMoCr4 +QT has a yield strength of 460 MPa (66.7 ksi) and a tensile strength of 660 MPa (95.7 ksi) — stronger than 55% of steel grades. Elongation at break is 18% and the elastic modulus is 210 GPa (30.5 Msi). G20NiMoCr4 +QT has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F).
Advantages
- Low embodied carbon — 1.9 kg CO₂/kg, better than 92% of steel grades
- Tough — resists crack growth — 120 MPa·√m (109.2 ksi·√in), better than 81% of steel grades
Limitations
- Limited formability — 20/100, worse than 80% of steel grades
G20NiMoCr4 +QT properties
Typical room-temperature values for G20NiMoCr4 +QT; 12 are specific to this condition. Other listed values are G20NiMoCr4 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
G20NiMoCr4 +QT has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F).
Mechanical16
G20NiMoCr4 +QT has a yield strength of 460 MPa (66.7 ksi) and a tensile strength of 660 MPa (95.7 ksi) — stronger than 55% of steel grades. Elongation at break is 18% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
G20NiMoCr4 +QT is rated for continuous service to 400°C (752 °F). It conducts heat at 42 W/m·K (24.3 BTU/hr·ft·°F), worse than 56% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
G20NiMoCr4 +QT conducts electricity at 7.8 % IACS, worse than 57% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (13/100), better than 66% of steel grades.
Sustainability4
Producing a kilogram of G20NiMoCr4 +QT takes about 24 MJ of energy and emits 1.9 kg of CO₂ — less than 97% of steel grades. Typical recycled content is 75%.
Manufacturability8
G20NiMoCr4 +QT's machinability is good (55/100, better than 62% of steel grades); weldability good (55/100); 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 G20NiMoCr4 +QT
Is G20NiMoCr4 easy to machine?
Machine in the annealed or as-normalized state where possible; in +QT use rigid setups, coated carbide, moderate speeds and generous coolant to handle the tough bainitic matrix and cast skin.
Can G20NiMoCr4 be welded?
Weldable with matching low-alloy Ni-Mo consumables, 150–250 °C preheat, low-hydrogen practice and a 580–620 °C PWHT; avoid welding after final temper without requalification.
Can G20NiMoCr4 be formed, bent or molded?
Supplied as sand or investment castings — feed heavy sections with risers and chills, allow ~2 % shrinkage and always follow with a homogenizing/austenitizing cycle.
What surface finishes work on G20NiMoCr4?
Shot-blast and prime; use paint, zinc-rich coatings, hard chrome or nitriding for wear faces — no anodizing on ferrous alloys.
G20NiMoCr4 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 C for weldability | 0.15 – 0.23 | 0.2 |
| Si | ≤ 0.6 | 0.35 |
| Mn | 0.5 – 1 | 0.8 |
| P | ≤ 0.02 | 0.01 |
| S | ≤ 0.02 | 0.01 |
| Cr | 0.3 – 0.6 | 0.45 |
| Mo | 0.35 – 0.6 | 0.5 |
| Ni | 0.8 – 1.2 | 1 |
| Vresidual | ≤ 0.05 | — |
| Curesidual | ≤ 0.3 | — |
| Fe | balance | — |
G20NiMoCr4 +QT — frequently asked
What is G20NiMoCr4 +QT used for?
G20NiMoCr4 +QT is typically used for reactor and pressure vessel castings, power plant components and heavy pressure-retaining parts. In short: best-welding cast alloy steel; pressure-vessel toughness grade; service to 400 °C.
What is the yield strength of G20NiMoCr4 +QT?
G20NiMoCr4 +QT has a typical yield strength of 460 MPa (66.7 ksi) and a tensile strength of 660 MPa (95.7 ksi) — stronger than 55% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is G20NiMoCr4 +QT easy to machine?
Reasonably — machinability is rated good (55/100, better than 62% of steel grades). Machine in the annealed or as-normalized state where possible; in +QT use rigid setups, coated carbide, moderate speeds and generous coolant to handle the tough bainitic matrix and cast skin.
Can G20NiMoCr4 +QT be welded?
Yes — weldability is rated good (55/100). Weldable with matching low-alloy Ni-Mo consumables, 150–250 °C preheat, low-hydrogen practice and a 580–620 °C PWHT; avoid welding after final temper without requalification.
What surface finishes work on G20NiMoCr4 +QT?
Shot-blast and prime; use paint, zinc-rich coatings, hard chrome or nitriding for wear faces — no anodizing on ferrous alloys.
Can G20NiMoCr4 +QT be formed, bent or molded?
Supplied as sand or investment castings — feed heavy sections with risers and chills, allow ~2 % shrinkage and always follow with a homogenizing/austenitizing cycle.
What is the maximum service temperature of G20NiMoCr4 +QT?
G20NiMoCr4 +QT is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between G20NiMoCr4 +QT and G20NiMoCr4-F?
+QT is the default condition — standard supply condition: best combination of ≈400–500 MPa yield with high sub-zero notch toughness in heavy sections. F: raw foundry state before heat treatment; not a delivery condition for pressure parts — coarse, segregated structure with poor toughness. Yield strength is 460 MPa in +QT versus 420 MPa in F.
Sources
- EN 10213 — Steel castings for pressure purposes — CEN (2016)
- EN 10293 — Steel castings for general engineering uses — CEN (2015)
- DIN 17205 — Quenched and tempered steel castings for general purposes — DIN (1992)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys (cast low-alloy steels) — ASM International (1990)
- ASM Handbook Vol.15 — Casting — ASM International (2008)
- SEW 310 — Physical properties of steels — Verlag Stahleisen (1992)
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.