Steel 37CrMo4 +CH
Heat-treated state
EN 37CrMo4
+CH = restricted (core) hardenability band
Narrowed hardenability scatter for reproducible core hardness and distortion in mass-produced gears/shafts.
Values for the +CH condition
Other 37CrMo4 tempers and conditions
37CrMo4 is listed in 12 conditions; see the grade overview at 37CrMo4.
Compare all 12 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Spheroidize annealed | Spheroidized structure with lowest hardness — choose for cold extrusion, cold heading and deep machining. | 360 | 570 | 24 | 185 HB | — |
Annealed | Softest general delivery state for heavy machining before customer heat treatment. | 400 | 620 | 21 | 205 HB | — |
Specified hardenability | Order this when the part is heat treated after machining and a guaranteed Jominy band is required; usually shipped +A/+AC. | 400 | 620 | 21 | 54 HRC | 8.1 % IACS |
+CHThis page Restricted (core) hardenability band | Narrowed hardenability scatter for reproducible core hardness and distortion in mass-produced gears/shafts. | 400 | 620 | 21 | 54 HRC | 8.2 % IACS |
Normalized | Uniform fine ferrite-pearlite/bainite for forgings before machining or as a moderate-strength delivery state. | 450 | 730 | 18 | 215 HB | — |
Treated to ferrite-pearlite structure and hardness range | Delivery state with a guaranteed hardness band for automated/high-volume machining. | 470 | 760 | 17 | 18 HRC | 8.1 % IACS |
+QT | Heavy bar/forging where hardenability limits core strength; pick for large shafts and flanges. | 620 | 900 | 15 | 26 HRC | — |
Cold drawn | Cold drawn from annealed stock for close tolerance and bright finish with raised strength but low ductility. | 680 | 800 | 9 | 240 HB | — |
+QTDefault Quenched and tempered | Standard stock condition for shafts and gears needing ~1000 MPa tensile with good toughness. | 780 | 1,000 | 13 | 31 HRC | — |
Quenched, tempered and peeled/turned bar | QT bar with machined surface: decarburized layer removed, good straightness for direct shaft use. | 780 | 1,000 | 13 | 31 HRC | 7.8 % IACS |
+QT + induction hardened surface | QT core with induction-hardened running surfaces for wear and contact fatigue (journals, gear teeth). | 780 | 1,000 | 12 | 54 HRC | 7.6 % IACS |
+QT | Small-diameter bar fully hardened through section; highest strength QT class. | 900 | 1,100 | 11 | 35 HRC | — |
What is 37CrMo4 +CH?
37CrMo4 +CH is 37CrMo4 heat treated to +CH — narrowed hardenability scatter for reproducible core hardness and distortion in mass-produced gears/shafts. 37CrMo4 +CH has a yield strength of 400 MPa (58 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 60% of steel grades. Elongation at break is 21% and the elastic modulus is 210 GPa (30.5 Msi). 37CrMo4 +CH has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,420°C (2,588 °F). +QT is the default condition FabDigit quotes; +CH is available on request or by drawing note.
37CrMo4 +CH properties
Typical room-temperature values for 37CrMo4 +CH; 23 are specific to this condition. Other listed values are 37CrMo4 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
37CrMo4 +CH has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical16
37CrMo4 +CH has a yield strength of 400 MPa (58 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 60% of steel grades. Elongation at break is 21% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
37CrMo4 +CH is rated for continuous service to 400°C (752 °F). It conducts heat at 45 W/m·K (26 BTU/hr·ft·°F), better than 66% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
37CrMo4 +CH conducts electricity at 8.2 % IACS, better than 61% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 37CrMo4 +CH takes about 27 MJ of energy and emits 2 kg of CO₂ — less than 59% of steel grades. Typical recycled content is 30%.
Manufacturability7
37CrMo4 +CH's machinability is good (58/100, better than 75% of steel grades); weldability fair (42/100); formability fair (45/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 37CrMo4 +CH
Is 37CrMo4 easy to machine?
Machine in +A/+AC/+N (≈200 HB) where possible; in +QT at 300 HB use rigid setups, coated carbide, 80–140 m/min and positive rake to control work hardening.
Can 37CrMo4 be welded?
CE ≈0.75 — preheat 250–350 °C, low-hydrogen consumables, and temper/stress relieve at 550–650 °C immediately after welding to avoid HAZ cracking.
Can 37CrMo4 be formed, bent or molded?
Hot forge 1100–850 °C then normalize; cold heading or extrusion only from spheroidized (+AC) stock; +QT bar is essentially not cold formable.
What surface finishes work on 37CrMo4?
No corrosion resistance bare — use phosphate+oil, black oxide, zinc or hard chrome plating; gas nitriding at 500–520 °C gives 550–650 HV cases without distorting the QT core.
37CrMo4 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 |
|---|---|---|
| Cmedium carbon, higher than 34CrMo4 | 0.34 – 0.41 | 0.37 |
| Si | ≤ 0.4 | 0.25 |
| Mn | 0.6 – 0.9 | 0.75 |
| P | ≤ 0.03 | — |
| Smax; S-grades (37CrS4-type) 0.020–0.040 | ≤ 0.04 | — |
| Cr | 0.9 – 1.2 | 1.05 |
| Mo | 0.15 – 0.3 | 0.22 |
| Niresidual | ≤ 0.3 | — |
| Curesidual | ≤ 0.3 | — |
| Fe | balance | — |
37CrMo4 +CH — frequently asked
What is 37CrMo4 +CH used for?
37CrMo4 +CH is typically used for shafts, gears, axles and machine tool parts. In short: between 34CrMo4 and 42CrMo4; through-hardening shaft steel; nitridable Q&T core.
What is the yield strength of 37CrMo4 +CH?
37CrMo4 +CH has a typical yield strength of 400 MPa (58 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 60% of steel grades. Strength varies by condition: see the 12 listed tempers.
Is 37CrMo4 +CH easy to machine?
Reasonably — machinability is rated good (58/100, better than 75% of steel grades). Machine in +A/+AC/+N (≈200 HB) where possible; in +QT at 300 HB use rigid setups, coated carbide, 80–140 m/min and positive rake to control work hardening.
Can 37CrMo4 +CH be welded?
With care — weldability is rated fair (42/100). CE ≈0.75 — preheat 250–350 °C, low-hydrogen consumables, and temper/stress relieve at 550–650 °C immediately after welding to avoid HAZ cracking.
What surface finishes work on 37CrMo4 +CH?
No corrosion resistance bare — use phosphate+oil, black oxide, zinc or hard chrome plating; gas nitriding at 500–520 °C gives 550–650 HV cases without distorting the QT core.
Can 37CrMo4 +CH be formed, bent or molded?
Hot forge 1100–850 °C then normalize; cold heading or extrusion only from spheroidized (+AC) stock; +QT bar is essentially not cold formable.
What is the maximum service temperature of 37CrMo4 +CH?
37CrMo4 +CH 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.
Sources
- EN 10083-3 Steels for quenching and tempering — Part 3: Alloy steels — CEN (2006)
- EN 10277 Bright steel products — technical delivery conditions — CEN (2018)
- SAE J404 / AISI 4137 chemical composition of alloy steels — SAE International (2020)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- Machinery's Handbook, 31st ed. (machinability ratings) — Industrial Press (2020)
- Cr-Mo quenched and tempered bar datasheets (Böhler/Ovako/Dörrenberg 1.7202-class) — various producers (2023)
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.