Steel 37CrNi3A
EN 37CrNi3A
37CrNi3A is a Ni-Cr low-alloy aerospace structural steel from the same GB family as 30CrMnSiNi2A, strengthened by quench and temper and often nitrided for wear resistance.
Reference datasheet — 37CrNi3A 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 QT500 condition
37CrNi3A tempers and conditions
37CrNi3A is supplied in 7 conditions, soft to hard. QT500 is the default FabDigit quotes; the values on this page are for it.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Softest condition for rough machining, deep hole drilling and cold straightening before hardening. | 460 | 750 | 19 | 235 HB | — |
Hot rolled | Raw mill bar or forging stock before machining and heat treatment; not for load-bearing service. | 560 | 900 | 14 | 30 HRC | 6 % IACS |
Normalized | Grain-refined, uniform structure for large forgings prior to final Q&T, or a moderate-strength delivery condition. | 620 | 880 | 16 | 27 HRC | 5.9 % IACS |
Q&T | Choose when impact toughness and low-temperature performance matter more than peak strength (heavy sections, cold climates). | 860 | 1,000 | 16 | 31 HRC | — |
Q&T + gas nitrided case | For journals and splines needing wear resistance and high surface fatigue strength without distorting the tempered core. | 1,000 | 1,150 | 12 | 60 HRC | 5.7 % IACS |
QT500Default Q&T | The standard supply/qualification condition: ≥1130 MPa with ≥47 J impact — general aircraft shafts, axles and structural fittings. | 1,030 | 1,180 | 13 | 37 HRC | — |
Q&T | Aerospace high-strength condition (~1450–1650 MPa) for landing-gear axles and highly loaded pins; watch hydrogen embrittlement and notch sensitivity. | 1,350 | 1,550 | 10 | 46 HRC | — |
What is 37CrNi3A?
37CrNi3A is a Ni-Cr low-alloy aerospace structural steel from the same GB family as 30CrMnSiNi2A, strengthened by quench and temper and often nitrided for wear resistance. It is chosen as bar, forged axles and pins where 1030 MPa yield, 1180 MPa tensile, 13% elongation and 350 HB (37 HRC) are sufficient and better machinability (score 40) and toughness matter more than peak strength. It has no corrosion resistance, is limited to about 400 °C, and welds only with preheat and post-weld temper; 34CrNiMo6 or 4340 fill the same role. 37CrNi3A 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). 37CrNi3A has a yield strength of 1,030 MPa (149 ksi) and a tensile strength of 1,180 MPa (171 ksi) — stronger than 93% of steel grades. Elongation at break is 13% and the elastic modulus is 210 GPa (30.5 Msi).
What is 37CrNi3A used for?
- landing gear axles
- aircraft structural shafts
- high-strength pins
Advantages
- High strength — 1,030 MPa (149 ksi), better than 93% of steel grades
- Polishes to a fine finish — 70/100, better than 87% of steel grades
Limitations
- High embodied carbon — 2.6 kg CO₂/kg, worse than 87% of steel grades
- Low electrical conductivity — 5.7 % IACS, worse than 80% of steel grades
- Limited ductility — 13%, worse than 78% of steel grades
- Difficult to machine — 40/100, worse than 77% of steel grades
- Difficult to weld — 25/100, worse than 77% of steel grades
37CrNi3A properties
Typical room-temperature values for 37CrNi3A-QT500; bars are the position among steel grades.
Physical3
37CrNi3A 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
37CrNi3A has a yield strength of 1,030 MPa (149 ksi) and a tensile strength of 1,180 MPa (171 ksi) — stronger than 93% of steel grades. Elongation at break is 13% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
37CrNi3A is rated for continuous service to 400°C (752 °F). It conducts heat at 35 W/m·K (20.2 BTU/hr·ft·°F), worse than 75% of steel grades. Thermal expansion is 11.8 µm/m·K (6.56 µin/in·°F).
Electrical3
37CrNi3A conducts electricity at 5.7 % IACS, worse than 80% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 37CrNi3A takes about 36 MJ of energy and emits 2.6 kg of CO₂ — more than 89% of steel grades. Typical recycled content is 25%.
Manufacturability7
37CrNi3A's machinability is fair (40/100, worse than 77% of steel grades); weldability poor (25/100); formability poor (25/100).
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. 37CrNi3A is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 37CrNi3A
Is 37CrNi3A easy to machine?
Rough machine annealed (≤269 HB) and finish after Q&T; use rigid setups, carbide inserts and reduced speeds above 40 HRC, grind for final tolerance.
Can 37CrNi3A be welded?
Poor weldability — preheat 250–350 °C, low-hydrogen consumables, and immediate post-weld temper below the part's tempering temperature; avoid welding fully hardened parts.
Can 37CrNi3A be formed, bent or molded?
Hot forge 1150–850 °C with slow cool or immediate anneal; cold forming limited to light straightening in the annealed state.
37CrNi3A 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 | 0.34 – 0.41 | 0.37 |
| Si | 0.17 – 0.37 | 0.27 |
| Mn | 0.3 – 0.6 | 0.45 |
| Cr | 1.2 – 1.6 | 1.4 |
| Ni | 3 – 3.5 | 3.25 |
| Curesidual | ≤ 0.2 | |
| Phigh-grade (A) limit | ≤ 0.03 | |
| Shigh-grade (A) limit; aerospace melts often ≤0.010 | ≤ 0.03 | |
| Fe | balance |
What surface finishes work on 37CrNi3A?
Not corrosion resistant — Cd or Zn-Ni plate, chrome plate on journals, or phosphate + primer; bake 190 °C ≥ 8 h after plating to avoid hydrogen embrittlement, and shot peen fatigue-critical fillets.
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
How much does 37CrNi3A cost?
37CrNi3A is a standard-cost steel ($$), cheaper than about 71% 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.
37CrNi3A — frequently asked
What is 37CrNi3A used for?
37CrNi3A is typically used for landing gear axles, aircraft structural shafts and high-strength pins. In short: most machinable of family; nitridable Ni-Cr grade; moderate 1030 MPa strength.
What is the yield strength of 37CrNi3A?
37CrNi3A has a typical yield strength of 1,030 MPa (149 ksi) and a tensile strength of 1,180 MPa (171 ksi) — stronger than 93% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is 37CrNi3A easy to machine?
Not especially — machinability is rated fair (40/100, worse than 77% of steel grades). Rough machine annealed (≤269 HB) and finish after Q&T; use rigid setups, carbide inserts and reduced speeds above 40 HRC, grind for final tolerance.
Can 37CrNi3A be welded?
Not readily — weldability is rated poor (25/100). Poor weldability — preheat 250–350 °C, low-hydrogen consumables, and immediate post-weld temper below the part's tempering temperature; avoid welding fully hardened parts.
What surface finishes work on 37CrNi3A?
Not corrosion resistant — Cd or Zn-Ni plate, chrome plate on journals, or phosphate + primer; bake 190 °C ≥ 8 h after plating to avoid hydrogen embrittlement, and shot peen fatigue-critical fillets.
Can 37CrNi3A be formed, bent or molded?
Hot forge 1150–850 °C with slow cool or immediate anneal; cold forming limited to light straightening in the annealed state.
What is the maximum service temperature of 37CrNi3A?
37CrNi3A 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.
What is the difference between 37CrNi3A-QT500 and 37CrNi3A-A?
QT500 is the default condition — the standard supply/qualification condition: ≥1130 MPa with ≥47 J impact — general aircraft shafts, axles and structural fittings. A: softest condition for rough machining, deep hole drilling and cold straightening before hardening. Yield strength is 1,030 MPa in QT500 versus 460 MPa in A.
How much does 37CrNi3A cost?
37CrNi3A is a standard-cost steel ($$), cheaper than about 71% 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
- GB/T 3077 (Alloy structural steels) (2015)
- ASM Handbook Vol. 1: Properties and Selection — Irons, Steels, and High-Performance Alloys — ASM International (1990)
- (China Aeronautical Materials Handbook) (2002)
- MMPDS-analogue data for 4340 / 34CrNiMo6 Q&T steels — Battelle / FAA (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.