Steel G20Mn5 +QT (Quenched and tempered)
Heat-treated state
EN 1.6220
Choose for heavier sections or where the highest low-temperature toughness and uniform through-thickness properties are required (wind-turbine and cryogenic-service castings).
Values for the +QT condition
Other G20Mn5 tempers and conditions
G20Mn5 is listed in 4 conditions; see the grade overview at G20Mn5.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Spheroidize annealed | Only for non-critical, low-stress parts or rough blanks that will be heat treated later; coarse dendritic structure gives poor and scattered toughness. | 280 | 520 | 16 | 160 HB | 9 % IACS |
+NDefault Normalized | Standard as-supplied condition for structural and general engineering steel castings; balanced strength, toughness and weldability at lowest cost. | 330 | 560 | 25 | 165 HB | — |
Normalized and tempered | Pick when residual stresses must be reduced and hardness/toughness scatter tightened on heavy or welded castings without full quenching. | 340 | 550 | 26 | 160 HB | — |
+QTThis page Quenched and tempered | Choose for heavier sections or where the highest low-temperature toughness and uniform through-thickness properties are required (wind-turbine and cryogenic-service castings). | 380 | 580 | 26 | 180 HB | — |
What is G20Mn5 +QT?
G20Mn5 +QT is G20Mn5 heat treated to +QT — choose for heavier sections or where the highest low-temperature toughness and uniform through-thickness properties are required (wind-turbine and cryogenic-service castings). G20Mn5 +QT has a yield strength of 380 MPa (55.1 ksi) and a tensile strength of 580 MPa (84.1 ksi) — weaker than 68% of steel grades. Elongation at break is 26% and the elastic modulus is 210 GPa (30.5 Msi). G20Mn5 +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). +N is the default condition FabDigit quotes; +QT is available on request or by drawing note.
Advantages
- Tough — resists crack growth — 140 MPa·√m (127.4 ksi·√in), better than 94% of steel grades
- Ductile — tolerates forming and impact — 26%, better than 82% of steel grades
- Conducts heat well — 48 W/m·K (27.7 BTU/hr·ft·°F), better than 79% of steel grades
- Readily welded — 78/100, better than 78% of steel grades
Limitations
- Hard to polish — 45/100, worse than 84% of steel grades
- Limited formability — 20/100, worse than 80% of steel grades
G20Mn5 +QT properties
Typical room-temperature values for G20Mn5 +QT; 16 are specific to this condition. Other listed values are G20Mn5 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
G20Mn5 +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
G20Mn5 +QT has a yield strength of 380 MPa (55.1 ksi) and a tensile strength of 580 MPa (84.1 ksi) — weaker than 68% of steel grades. Elongation at break is 26% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
G20Mn5 +QT is rated for continuous service to 400°C (752 °F). It conducts heat at 48 W/m·K (27.7 BTU/hr·ft·°F), better than 79% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
G20Mn5 +QT conducts electricity at 9 % IACS, better than 71% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (11/100), worse than 73% of steel grades.
Sustainability4
Producing a kilogram of G20Mn5 +QT takes about 26 MJ of energy and emits 2 kg of CO₂ — less than 64% of steel grades. Typical recycled content is 85%.
Manufacturability8
G20Mn5 +QT's machinability is fair (54/100, better than 54% of steel grades); weldability very good (78/100); formability poor (20/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with G20Mn5 +QT
Is G20Mn5 easy to machine?
Machines like normalized 1020–1030 steel: use coated carbide, 120–200 m/min turning, watch for hard sand/scale skin on the first cut.
Can G20Mn5 be welded?
Excellent weldability (CEV ≈ 0.42–0.48); use low-hydrogen electrodes/wire, preheat 100–150 °C on sections over ~30 mm and PWHT 580–620 °C for critical or heavy repairs.
Can G20Mn5 be formed, bent or molded?
Sand, shell or investment casting with good fluidity but high solidification shrinkage (~2 %); generous risering, chills and directional-solidification design are essential to avoid centerline shrinkage.
What surface finishes work on G20Mn5?
No anodizing; shot blast then zinc-rich primer, epoxy paint, hot-dip galvanizing or hard-chrome/nitriding on bearing surfaces for wear.
G20Mn5 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 |
|---|---|---|
| C | 0.17 – 0.23 | 0.2 |
| Si | ≤ 0.6 | 0.4 |
| Mn | 1 – 1.6 | 1.3 |
| Pmax 0.025 in some grades of EN 10293 | ≤ 0.02 | 0.01 |
| S | ≤ 0.02 | 0.01 |
| Crresidual | ≤ 0.3 | 0.15 |
| Niresidual | ≤ 0.8 | 0.2 |
| Moresidual | ≤ 0.12 | 0.05 |
| Curesidual | ≤ 0.3 | 0.15 |
| Vresidual | ≤ 0.03 | 0.01 |
| Fe | balance | — |
G20Mn5 +QT — frequently asked
What is G20Mn5 +QT used for?
G20Mn5 +QT is typically used for wind turbine hubs and nacelle castings, construction machinery parts, railway components and general structural steel castings. In short: workhorse structural cast steel; best-weldable cast steel; wind-energy casting standard.
What is the yield strength of G20Mn5 +QT?
G20Mn5 +QT has a typical yield strength of 380 MPa (55.1 ksi) and a tensile strength of 580 MPa (84.1 ksi) — weaker than 68% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is G20Mn5 +QT easy to machine?
Reasonably — machinability is rated fair (54/100, better than 54% of steel grades). Machines like normalized 1020–1030 steel: use coated carbide, 120–200 m/min turning, watch for hard sand/scale skin on the first cut.
Can G20Mn5 +QT be welded?
Yes — weldability is rated very good (78/100). Excellent weldability (CEV ≈ 0.42–0.48); use low-hydrogen electrodes/wire, preheat 100–150 °C on sections over ~30 mm and PWHT 580–620 °C for critical or heavy repairs.
What surface finishes work on G20Mn5 +QT?
No anodizing; shot blast then zinc-rich primer, epoxy paint, hot-dip galvanizing or hard-chrome/nitriding on bearing surfaces for wear.
Can G20Mn5 +QT be formed, bent or molded?
Sand, shell or investment casting with good fluidity but high solidification shrinkage (~2 %); generous risering, chills and directional-solidification design are essential to avoid centerline shrinkage.
What is the maximum service temperature of G20Mn5 +QT?
G20Mn5 +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 G20Mn5 +N and G20Mn5-AC?
+N is the default condition — standard as-supplied condition for structural and general engineering steel castings; balanced strength, toughness and weldability at lowest cost. AC: only for non-critical, low-stress parts or rough blanks that will be heat treated later; coarse dendritic structure gives poor and scattered toughness. Yield strength is 330 MPa in +N versus 280 MPa in AC.
Sources
- EN 10213 — Steel castings for pressure purposes — CEN (2016)
- EN 10293 — Steel castings for general engineering uses — CEN (2015)
- ASTM A216/A216M Grade WCC — ASTM International (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)
- SEW 310 — Physical properties of steels — VDEh (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.