Steel 20MnTiB-QT450
Heat-treated state
GB 20MnTiB
Use where toughness and machinability matter more than peak strength, e.g. shafts and links that are not carburized.
Values for the QT450 condition
Other 20MnTiB tempers and conditions
20MnTiB is listed in 7 conditions; see the grade overview at 20MnTiB.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ADefault Solution annealed | Standard delivery condition for gear-blank bar: soft, uniform structure for hobbing and shaping before carburizing. | 380 | 620 | 22 | 170 HB | — |
Hot rolled | Mill as-rolled bar; hardness scatter is high, normally re-annealed or normalized before machining. | 430 | 700 | 18 | 14 HRC | 8 % IACS |
Normalized | Choose to homogenize forgings and refine grain before carburizing when distortion control matters. | 450 | 700 | 19 | 14 HRC | 8 % IACS |
Cold drawn | Pick for close-tolerance bright bar used on automatics; strength up, ductility down versus annealed. | 620 | 750 | 11 | 18 HRC | 8 % IACS |
QT450This page oil quenched + tempered ≈450 °C (medium-hardness through-hardened) | Use where toughness and machinability matter more than peak strength, e.g. shafts and links that are not carburized. | 780 | 950 | 15 | 30 HRC | — |
Carburized and hardened | The production condition for gears: 0.6–1.4 mm hardened case at 58–62 HRC over a 30–40 HRC tough core. | 950 | 1,200 | 10 | 60 HRC | — |
oil quenched 860 °C + tempered 200 °C (GB/T 3077 test condition) | The specification heat treatment used for acceptance testing; also used for through-hardened high-strength shafts and fasteners. | 980 | 1,180 | 12 | 38 HRC | — |
What is 20MnTiB-QT450?
20MnTiB-QT450 is 20MnTiB heat treated to QT450 — use where toughness and machinability matter more than peak strength, e.g. shafts and links that are not carburized. 20MnTiB-QT450 has a yield strength of 780 MPa (113 ksi) and a tensile strength of 950 MPa (138 ksi) — stronger than 86% of steel grades. Elongation at break is 15% and the elastic modulus is 210 GPa (30.5 Msi). 20MnTiB-QT450 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). A is the default condition FabDigit quotes; QT450 is available on request or by drawing note.
Advantages
- High strength — 780 MPa (113 ksi), better than 86% of steel grades
20MnTiB-QT450 properties
Typical room-temperature values for 20MnTiB-QT450; 10 are specific to this condition. Other listed values are 20MnTiB reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
20MnTiB-QT450 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).
Mechanical13
20MnTiB-QT450 has a yield strength of 780 MPa (113 ksi) and a tensile strength of 950 MPa (138 ksi) — stronger than 86% of steel grades. Elongation at break is 15% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
20MnTiB-QT450 is rated for continuous service to 350°C (662 °F). It conducts heat at 44 W/m·K (25.4 BTU/hr·ft·°F), better than 57% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
20MnTiB-QT450 conducts electricity at 8 % IACS, better than 55% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 20MnTiB-QT450 takes about 25 MJ of energy and emits 2 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 25%.
Manufacturability7
20MnTiB-QT450's machinability is fair (42/100, worse than 73% of steel grades); weldability fair (40/100); formability good (55/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 20MnTiB-QT450
Is 20MnTiB easy to machine?
Machine in the annealed (≤187 HB) or normalized state with coated carbide; sticky low-carbon chips need positive rake and good coolant — machinability roughly 55–60 % of 1212.
Can 20MnTiB be welded?
Poor to fair: carbon equivalent ~0.6 with boron, so use low-hydrogen consumables, 150–250 °C preheat and immediate stress relief; never weld after carburizing.
Can 20MnTiB be formed, bent or molded?
Hot forge 1150–850 °C then normalize/anneal; cold heading and moderate cold forming are practical only in the spheroidize-annealed condition.
What surface finishes work on 20MnTiB?
No corrosion resistance — protect with phosphate + oil, zinc or manganese phosphate; gear flanks are usually shot-peened and ground after carburizing, and plating must avoid hydrogen embrittlement (bake 190–220 °C).
20MnTiB 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 – 0.24 | 0.2 |
| Si | 0.17 – 0.37 | 0.27 |
| Mnmain hardenability element | 1.3 – 1.6 | 1.45 |
| Tifixes N, refines austenite grain, protects boron | 0.04 – 0.1 | 0.07 |
| Bhardenability booster | 5×10⁻⁴ – 0 | 0 |
| Crresidual | ≤ 0.3 | — |
| Niresidual | ≤ 0.3 | — |
| Curesidual | ≤ 0.3 | — |
| P | ≤ 0.04 | — |
| S | ≤ 0.04 | — |
| Fe | balance | — |
20MnTiB-QT450 — frequently asked
What is 20MnTiB-QT450 used for?
20MnTiB-QT450 is typically used for truck gears, tractor gears and carburized shafts. In short: titanium-refined carburizing steel; truck and tractor gear grade; fair weldability at best.
What is the yield strength of 20MnTiB-QT450?
20MnTiB-QT450 has a typical yield strength of 780 MPa (113 ksi) and a tensile strength of 950 MPa (138 ksi) — stronger than 86% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is 20MnTiB-QT450 easy to machine?
Not especially — machinability is rated fair (42/100, worse than 73% of steel grades). Machine in the annealed (≤187 HB) or normalized state with coated carbide; sticky low-carbon chips need positive rake and good coolant — machinability roughly 55–60 % of 1212.
Can 20MnTiB-QT450 be welded?
With care — weldability is rated fair (40/100). Poor to fair: carbon equivalent ~0.6 with boron, so use low-hydrogen consumables, 150–250 °C preheat and immediate stress relief; never weld after carburizing.
What surface finishes work on 20MnTiB-QT450?
No corrosion resistance — protect with phosphate + oil, zinc or manganese phosphate; gear flanks are usually shot-peened and ground after carburizing, and plating must avoid hydrogen embrittlement (bake 190–220 °C).
Can 20MnTiB-QT450 be formed, bent or molded?
Hot forge 1150–850 °C then normalize/anneal; cold heading and moderate cold forming are practical only in the spheroidize-annealed condition.
What is the maximum service temperature of 20MnTiB-QT450?
20MnTiB-QT450 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 20MnTiB-A and 20MnTiB-QT200?
A is the default condition — standard delivery condition for gear-blank bar: soft, uniform structure for hobbing and shaping before carburizing. QT200: the specification heat treatment used for acceptance testing; also used for through-hardened high-strength shafts and fasteners. Yield strength is 380 MPa in A versus 980 MPa in QT200.
Sources
- GB/T 3077 (Alloy structural steels) (2015)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.4 — Heat Treating (boron steels, carburizing) — ASM International (1991)
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.