Steel 30CrMnTi-QT400
Heat-treated state
GB 30CrMnTi
QT400 = quenched + 400 °C temper
Medium temper for springy, high-strength shafts and torsion members needing more toughness than the 200 °C temper.
Values for the QT400 condition
Other 30CrMnTi tempers and conditions
30CrMnTi is listed in 9 conditions; see the grade overview at 30CrMnTi.
Compare all 9 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ADefault Solution annealed | Standard mill-supplied soft condition for machining before carburising or hardening. | 480 | 780 | 18 | 207 HB | — |
Normalized | Choose to homogenise structure and improve machinability/dimensional stability of forgings before final heat treatment. | 570 | 900 | 15 | 22 HRC | 7.8 % IACS |
Cold drawn | Pick for close-tolerance, bright-surface bar used for shafts and pins machined with minimum stock removal. | 700 | 880 | 10 | 24 HRC | 7.8 % IACS |
QT 28–32 HRC | General quenched-and-tempered condition for shafts and machined gear blanks that must stay machinable after heat treatment. | 850 | 1,000 | 14 | 30 HRC | — |
Induction hardened | Use when only tooth flanks or journals need 52–58 HRC wear resistance over a tough quenched-and-tempered core. | 880 | 1,050 | 12 | 55 HRC | 7.5 % IACS |
QT 34–38 HRC | Higher-strength through-hardened condition for heavily loaded shafts and couplings still finish-machinable with carbide tooling. | 1,000 | 1,150 | 12 | 36 HRC | — |
QT400This page Quenched + 400 °C temper | Medium temper for springy, high-strength shafts and torsion members needing more toughness than the 200 °C temper. | 1,180 | 1,330 | 11 | 42 HRC | — |
Carburized & hardened | Select for heavy-duty transmission gears needing a hard wear-resistant case over a stronger core than 20CrMnTi gives. | 1,200 | 1,500 | 9 | 60 HRC | — |
Double quench (880 °C + 850 °C oil) + 200 °C temper | The standard GB/T 3077 acceptance condition — maximum strength and wear resistance for gears and splines, low toughness reserve. | 1,270 | 1,560 | 10 | 46 HRC | — |
What is 30CrMnTi-QT400?
30CrMnTi-QT400 is 30CrMnTi heat treated to QT400 — medium temper for springy, high-strength shafts and torsion members needing more toughness than the 200 °C temper. 30CrMnTi-QT400 has a yield strength of 1,180 MPa (171 ksi) and a tensile strength of 1,330 MPa (193 ksi) — stronger than 94% of steel grades. Elongation at break is 11% and the elastic modulus is 210 GPa (30.5 Msi). 30CrMnTi-QT400 has a density of 7.82 g/cm³ (0.283 lb/in³), lighter than 82% of steel grades. It melts at 1,425°C (2,597 °F). A is the default condition FabDigit quotes; QT400 is available on request or by drawing note.
Advantages
- High strength — 1,180 MPa (171 ksi), better than 94% of steel grades
Limitations
- Difficult to machine — 25/100, worse than 93% of steel grades
- Limited ductility — 11%, worse than 89% of steel grades
30CrMnTi-QT400 properties
Typical room-temperature values for 30CrMnTi-QT400; 10 are specific to this condition. Other listed values are 30CrMnTi reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
30CrMnTi-QT400 has a density of 7.82 g/cm³ (0.283 lb/in³), lighter than 82% of steel grades. It melts at 1,425°C (2,597 °F).
Mechanical16
30CrMnTi-QT400 has a yield strength of 1,180 MPa (171 ksi) and a tensile strength of 1,330 MPa (193 ksi) — stronger than 94% of steel grades. Elongation at break is 11% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
30CrMnTi-QT400 is rated for continuous service to 350°C (662 °F). It conducts heat at 42 W/m·K (24.3 BTU/hr·ft·°F), worse than 56% of steel grades. Thermal expansion is 11.8 µm/m·K (6.56 µin/in·°F).
Electrical3
30CrMnTi-QT400 conducts electricity at 7.8 % IACS, worse than 57% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 30CrMnTi-QT400 takes about 29 MJ of energy and emits 2.1 kg of CO₂ — less than 53% of steel grades. Typical recycled content is 30%.
Manufacturability7
30CrMnTi-QT400's machinability is poor (25/100, worse than 93% of steel grades); weldability poor (32/100); formability fair (45/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 30CrMnTi-QT400
Is 30CrMnTi easy to machine?
Machine in the annealed (≤229 HB) or 28–32 HRC condition with sharp carbide tooling and rigid setups; leave 0.2–0.4 mm grinding stock for post-hardening finishing of gear teeth and journals.
Can 30CrMnTi be welded?
Poor weldability (CE ≈ 0.7–0.8) — preheat 250–350 °C, use low-hydrogen consumables and temper immediately after welding; avoid welding carburised or hardened parts.
Can 30CrMnTi be formed, bent or molded?
Hot forge 1150–1200 °C finishing above 850 °C followed by slow cool and annealing; cold forming limited to mild bending in the annealed state.
What surface finishes work on 30CrMnTi?
Cannot be anodised — protect with Mn-phosphate (also good for gear run-in), black oxide, zinc plating or oil; shot peening after hardening significantly raises bending fatigue life.
30CrMnTi 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 | 0.24 – 0.32 | 0.3 |
| Si | 0.17 – 0.37 | 0.27 |
| Mn | 0.8 – 1.1 | 0.95 |
| Cr | 1 – 1.3 | 1.15 |
| Tigrain refiner / carbide former | 0.04 – 0.1 | 0.07 |
| Niresidual | ≤ 0.3 | — |
| Curesidual | ≤ 0.25 | — |
| Pimpurity | ≤ 0.03 | — |
| Simpurity | ≤ 0.03 | — |
| Fe | balance | — |
30CrMnTi-QT400 — frequently asked
What is 30CrMnTi-QT400 used for?
30CrMnTi-QT400 is typically used for heavy truck gears, transmission shafts and sprockets. In short: higher-core-strength 20CrMnTi; carburising gear steel; poor weldability, high strength.
What is the yield strength of 30CrMnTi-QT400?
30CrMnTi-QT400 has a typical yield strength of 1,180 MPa (171 ksi) and a tensile strength of 1,330 MPa (193 ksi) — stronger than 94% of steel grades. Strength varies by condition: see the 9 listed tempers.
Is 30CrMnTi-QT400 easy to machine?
Not especially — machinability is rated poor (25/100, worse than 93% of steel grades). Machine in the annealed (≤229 HB) or 28–32 HRC condition with sharp carbide tooling and rigid setups; leave 0.2–0.4 mm grinding stock for post-hardening finishing of gear teeth and journals.
Can 30CrMnTi-QT400 be welded?
Not readily — weldability is rated poor (32/100). Poor weldability (CE ≈ 0.7–0.8) — preheat 250–350 °C, use low-hydrogen consumables and temper immediately after welding; avoid welding carburised or hardened parts.
What surface finishes work on 30CrMnTi-QT400?
Cannot be anodised — protect with Mn-phosphate (also good for gear run-in), black oxide, zinc plating or oil; shot peening after hardening significantly raises bending fatigue life.
Can 30CrMnTi-QT400 be formed, bent or molded?
Hot forge 1150–1200 °C finishing above 850 °C followed by slow cool and annealing; cold forming limited to mild bending in the annealed state.
What is the maximum service temperature of 30CrMnTi-QT400?
30CrMnTi-QT400 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 30CrMnTi-A and 30CrMnTi-QT200?
A is the default condition — standard mill-supplied soft condition for machining before carburising or hardening. QT200: the standard GB/T 3077 acceptance condition — maximum strength and wear resistance for gears and splines, low toughness reserve. Yield strength is 480 MPa in A versus 1,270 MPa in QT200.
Sources
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.4A — Steel Heat Treating Fundamentals and Processes — ASM International (2013)
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.