Steel 37CrMo4
EN 37CrMo4
37CrMo4 (1.7202, close to AISI 4137) is a medium-carbon chromium-molybdenum through-hardening steel to the EN 10083 family, delivered quenched and tempered at about 780 MPa yield, 1000 MPa tensile, 13 % elongation and 300 HB (31 HRC).
Reference datasheet — 37CrMo4 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the +QT condition
37CrMo4 tempers and conditions
37CrMo4 is supplied in 12 conditions, soft to hard. +QT is the default FabDigit quotes; the values on this page are for it.
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 |
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?
37CrMo4 (1.7202, close to AISI 4137) is a medium-carbon chromium-molybdenum through-hardening steel to the EN 10083 family, delivered quenched and tempered at about 780 MPa yield, 1000 MPa tensile, 13 % elongation and 300 HB (31 HRC). It sits between 34CrMo4 and 42CrMo4 in strength and hardenability and is used for shafts, gears and highly loaded machine parts, supplied as bar and forging stock with section-specific +QT-16 and +QT-100 properties. Weldability is limited (score 30), cold formability is low (score 20), service is capped near 400 °C and the bare surface has no corrosion resistance. Move to 42CrMo4 for more strength in thick sections. 37CrMo4 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). 37CrMo4 has a yield strength of 780 MPa (113 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 86% of steel grades. Elongation at break is 13% and the elastic modulus is 210 GPa (30.5 Msi).
What is 37CrMo4 used for?
- Shafts
- Gears
- Axles
- Machine tool parts
Advantages
- High strength — 780 MPa (113 ksi), better than 86% of steel grades
Limitations
- Limited formability — 20/100, worse than 80% of steel grades
- Limited ductility — 13%, worse than 78% of steel grades
37CrMo4 properties
Typical room-temperature values for 37CrMo4-+QT; bars are the position among steel grades.
Physical3
37CrMo4 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 has a yield strength of 780 MPa (113 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 86% of steel grades. Elongation at break is 13% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
37CrMo4 is rated for continuous service to 400°C (752 °F). It conducts heat at 42 W/m·K (24.3 BTU/hr·ft·°F), worse than 56% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
37CrMo4 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 37CrMo4 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's machinability is fair (42/100, worse than 73% of steel grades); weldability poor (30/100); formability poor (20/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the steel family
Yield strength against density for every steel grade FabDigit runs. 37CrMo4 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 37CrMo4
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.
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 |
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.
Surface treatments FabDigit runs on steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Organic Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel 37CrMo4 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- EN / DIN / Werkstoff-Nr.
- 1.7202
- Similar grades
- 413737CrMo
How much does 37CrMo4 cost?
37CrMo4 is a budget-cost steel ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
37CrMo4 — frequently asked
What is 37CrMo4 used for?
37CrMo4 is typically used for shafts, gears, axles and machine tool parts. In short: between 34CrMo4 and 42CrMo4; through-hardening shaft steel; nitridable Q&T core.
What is the yield strength of 37CrMo4?
37CrMo4 has a typical yield strength of 780 MPa (113 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 86% of steel grades. Strength varies by condition: see the 12 listed tempers.
Is 37CrMo4 easy to machine?
Not especially — machinability is rated fair (42/100, worse than 73% of steel grades). Machine in +A/+AC/+N (≈200 HB) where possible; in +QT at 300 HB use rigid setups, coated carbide, 80–140 m/min and positive rake to control work hardening.
Can 37CrMo4 be welded?
Not readily — weldability is rated poor (30/100). CE ≈0.75 — preheat 250–350 °C, low-hydrogen consumables, and temper/stress relieve at 550–650 °C immediately after welding to avoid HAZ cracking.
What surface finishes work on 37CrMo4?
No corrosion resistance bare — use phosphate+oil, black oxide, zinc or hard chrome plating; gas nitriding at 500–520 °C gives 550–650 HV cases without distorting the QT core.
Can 37CrMo4 be formed, bent or molded?
Hot forge 1100–850 °C then normalize; cold heading or extrusion only from spheroidized (+AC) stock; +QT bar is essentially not cold formable.
What is the maximum service temperature of 37CrMo4?
37CrMo4 is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does 37CrMo4 cost?
37CrMo4 is a budget-cost steel ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
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; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.