Steel 20Cr-QT200
Heat-treated state
GB 20Cr · AISI/SAE 5120 · JIS SCr420
QT200 = quenched 880 °C (water/oil) + tempered 200 °C
The condition in which GB/T 3077 mechanical properties are certified; direct hardening for small high-strength parts.
Values for the QT200 condition
Other 20Cr tempers and conditions
20Cr is listed in 7 conditions; see the grade overview at 20Cr.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Softest condition; choose for deep cold forming, cold heading or heavy pre-machining before carburizing. | 300 | 520 | 27 | 156 HB | — |
HRDefault Hot rolled | Standard mill stock condition for 20Cr bar; rough-machine then carburize and harden. | 380 | 600 | 22 | 170 HB | — |
Normalized | Uniform fine-grained structure with good chip control; standard pre-treatment before carburizing. | 400 | 620 | 22 | 179 HB | — |
Quenched + high tempered 500–600 °C | Tough, machinable through-hardened condition for shafts and fasteners that will not be carburized. | 550 | 750 | 18 | 20 HRC | — |
Cold drawn | Bright, close-tolerance bar for small shafts and pins machined to near-net size before case hardening. | 570 | 700 | 12 | 200 HB | — |
QT200This page Quenched 880 °C (water/oil) + tempered 200 °C | The condition in which GB/T 3077 mechanical properties are certified; direct hardening for small high-strength parts. | 620 | 900 | 13 | 30 HRC | — |
Carburized 900–930 °C, quenched + 180–200 °C temper | Service condition for gears, pins and splines: hard wear-resistant case over a tough low-carbon core. | 720 | 1,000 | 10 | 60 HRC | — |
What is 20Cr-QT200?
20Cr-QT200 is 20Cr heat treated to QT200 — the condition in which GB/T 3077 mechanical properties are certified; direct hardening for small high-strength parts. 20Cr-QT200 has a yield strength of 620 MPa (89.9 ksi) and a tensile strength of 900 MPa (131 ksi) — stronger than 78% of steel grades. Elongation at break is 13% and the elastic modulus is 210 GPa (30.5 Msi). 20Cr-QT200 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). HR is the default condition FabDigit quotes; QT200 is available on request or by drawing note.
Advantages
- High strength — 620 MPa (89.9 ksi), better than 78% of steel grades
Limitations
- Limited service temperature — 180°C (356 °F), worse than 98% of steel grades
- Limited ductility — 13%, worse than 78% of steel grades
20Cr-QT200 properties
Typical room-temperature values for 20Cr-QT200; 14 are specific to this condition. Other listed values are 20Cr reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
20Cr-QT200 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).
Mechanical15
20Cr-QT200 has a yield strength of 620 MPa (89.9 ksi) and a tensile strength of 900 MPa (131 ksi) — stronger than 78% of steel grades. Elongation at break is 13% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
20Cr-QT200 is rated for continuous service to 180°C (356 °F). It conducts heat at 44 W/m·K (25.4 BTU/hr·ft·°F), better than 57% of steel grades. Thermal expansion is 11.9 µm/m·K (6.61 µin/in·°F).
Electrical3
20Cr-QT200 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 20Cr-QT200 takes about 27 MJ of energy and emits 2.1 kg of CO₂ — less than 59% of steel grades. Typical recycled content is 30%.
Manufacturability7
20Cr-QT200's machinability is fair (42/100, worse than 73% of steel grades); weldability fair (35/100); formability good (60/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 20Cr-QT200
Is 20Cr easy to machine?
Best machined normalized or annealed (≈65 % of AISI 1212) with carbide tooling; leave 0.2–0.4 mm grinding stock because carburize-quench distortion must be corrected after heat treatment.
Can 20Cr be welded?
Weldable with low-hydrogen electrodes at 150–250 °C preheat plus post-weld stress relief; do not weld carburized surfaces — the high-carbon case cracks.
Can 20Cr be formed, bent or molded?
Good cold heading and upsetting in the spheroidize-annealed state; hot forge at 1150–1200 °C and finish above 850 °C, then normalize to restore grain size.
What surface finishes work on 20Cr?
No passive film — protect with phosphate + oil, black oxide, Zn or Zn-Ni plating (bake to avoid hydrogen embrittlement after case hardening); case-hardened surfaces are finished by grinding or honing.
20Cr 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 | 0.18 – 0.24 | 0.21 |
| Si | 0.17 – 0.37 | 0.27 |
| Mn | 0.5 – 0.8 | 0.65 |
| Cr | 0.7 – 1 | 0.85 |
| Niresidual | ≤ 0.3 | — |
| Curesidual | ≤ 0.25 | — |
| Moresidual | ≤ 0.1 | — |
| P | ≤ 0.03 | — |
| S | ≤ 0.03 | — |
| Fe | balance | — |
20Cr-QT200 — frequently asked
What is 20Cr-QT200 used for?
20Cr-QT200 is typically used for gears, shafts, pins and small carburized parts. In short: entry-level carburizing steel; hard case, tough core; cheaper than 20CrMnTi.
What is the yield strength of 20Cr-QT200?
20Cr-QT200 has a typical yield strength of 620 MPa (89.9 ksi) and a tensile strength of 900 MPa (131 ksi) — stronger than 78% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is 20Cr-QT200 easy to machine?
Not especially — machinability is rated fair (42/100, worse than 73% of steel grades). Best machined normalized or annealed (≈65 % of AISI 1212) with carbide tooling; leave 0.2–0.4 mm grinding stock because carburize-quench distortion must be corrected after heat treatment.
Can 20Cr-QT200 be welded?
With care — weldability is rated fair (35/100). Weldable with low-hydrogen electrodes at 150–250 °C preheat plus post-weld stress relief; do not weld carburized surfaces — the high-carbon case cracks.
What surface finishes work on 20Cr-QT200?
No passive film — protect with phosphate + oil, black oxide, Zn or Zn-Ni plating (bake to avoid hydrogen embrittlement after case hardening); case-hardened surfaces are finished by grinding or honing.
Can 20Cr-QT200 be formed, bent or molded?
Good cold heading and upsetting in the spheroidize-annealed state; hot forge at 1150–1200 °C and finish above 850 °C, then normalize to restore grain size.
What is the maximum service temperature of 20Cr-QT200?
20Cr-QT200 is rated for continuous use to about 180°C (356 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 20Cr-HR and 20Cr CARB?
HR is the default condition — standard mill stock condition for 20Cr bar; rough-machine then carburize and harden. CARB: service condition for gears, pins and splines: hard wear-resistant case over a tough low-carbon core. Yield strength is 380 MPa in HR versus 720 MPa in CARB.
Sources
- JIS G 4053 (SCr420) Low-alloyed steels for machine structural use — JISC (2016)
- EN 10084 Case hardening steels (20Cr4 / 1.7027) — CEN (2008)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- Machinery's Handbook (machinability ratings) — Industrial Press (2020)
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.