Steel 40CrNiMoA · heat-treated state
Steel 40CrNiMoA Normalized
Properties of the Normalized condition, compared with the other 40CrNiMoA tempers.
Uniform, refined structure for forgings before final Q&T; already strong but with limited ductility because of the air-hardened bainite/martensite.
What is 40CrNiMoA Normalized?
40CrNiMoA Normalized is 40CrNiMoA heat treated to Normalized — uniform, refined structure for forgings before final Q&T; already strong but with limited ductility because of the air-hardened bainite/martensite. 40CrNiMoA Normalized has a yield strength of 860 MPa (125 ksi) and a tensile strength of 1,280 MPa (186 ksi) — stronger than 89% of steel grades. Elongation at break is 12% and the elastic modulus is 207 GPa (30 Msi). 40CrNiMoA Normalized 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). Q&T is the default condition FabDigit quotes; Normalized is available on request or by drawing note.
Advantages
- High strength — 860 MPa (125 ksi), better than 89% of steel grades
- Polishes to a fine finish — 65/100, better than 78% of steel grades
Limitations
- Limited formability — 15/100, worse than 87% of steel grades
- Difficult to machine — 33/100, worse than 86% of steel grades
- Limited ductility — 12%, worse than 84% of steel grades
40CrNiMoA Normalized properties
Typical room-temperature values for 40CrNiMoA Normalized — 11 properties are specific to this condition; the rest are grade-level values shared by every 40CrNiMoA temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
40CrNiMoA Normalized 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
40CrNiMoA Normalized has a yield strength of 860 MPa (125 ksi) and a tensile strength of 1,280 MPa (186 ksi) — stronger than 89% of steel grades. Elongation at break is 12% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
40CrNiMoA Normalized is rated for continuous service to 400°C (752 °F). It conducts heat at 44 W/m·K (25.4 BTU/hr·ft·°F), better than 57% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
40CrNiMoA Normalized conducts electricity at 7 % IACS, worse than 74% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (15/100), better than 75% of steel grades.
Sustainability4
Producing a kilogram of 40CrNiMoA Normalized takes about 32 MJ of energy and emits 2.3 kg of CO₂ — more than 70% of steel grades. Typical recycled content is 30%.
Manufacturability8
40CrNiMoA Normalized's machinability is poor (33/100, worse than 86% of steel grades); weldability poor (30/100); formability poor (15/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other 40CrNiMoA tempers and conditions
40CrNiMoA is also supplied in 9 other conditions. The full side-by-side table is on the 40CrNiMoA overview.
- Q&TDefaultStandard stocked condition: balanced ~1000–1100 MPa strength with high toughness for shafts, gears and high-strength fasteners.950 MPa yield · 34 HRC
- Q&T 48-52 HRCMaximum strength (~1800 MPa) condition for wear parts and tooling; brittle, notch- and hydrogen-sensitive, so avoid stress concentrations and plate only with post-bake.1,600 MPa yield · 50 HRC
- Q&T 42-46 HRCHigh-strength ~1500 MPa condition for torsion bars, landing-gear-type parts and tooling; toughness and machinability drop sharply.1,350 MPa yield · 44 HRC
- Q&T 38-42 HRCUse for higher-strength ~1300 MPa parts such as aerospace fittings and heavy-duty bolts where some ductility is still needed.1,200 MPa yield · 40 HRC
- Q&T 32-36 HRCMost common ordered hardness band for gears, connecting rods and driveline shafts; good strength/toughness compromise.1,000 MPa yield · 34 HRC
- NormalizedUniform, refined structure for forgings before final Q&T; already strong but with limited ductility because of the air-hardened bainite/martensite.860 MPa yield · 39 HRC
- Q&T 28-32 HRCPick when toughness and machinability matter more than strength, e.g. large forged shafts and pressure-containing parts.860 MPa yield · 30 HRC
- CDBright, close-tolerance bar for direct machining of moderately loaded parts without further heat treatment.720 MPa yield · 250 HB
- AnnealedSoftest condition for deep machining, cold forming or as a pre-heat-treat stock; hardness capped at 269 HB per GB/T 3077.470 MPa yield · 217 HB
Working with 40CrNiMoA Normalized
Is 40CrNiMoA easy to machine?
Machine in the annealed or ≤32 HRC condition with rigid setups, sharp carbide and generous coolant; above 40 HRC switch to CBN/ceramic turning or grinding, and rough before final temper where possible.
Can 40CrNiMoA be welded?
High carbon equivalent means preheat 250–350 °C, low-hydrogen filler (e.g. ER100S/ER110S or matching), interpass control and immediate PWHT/re-temper; avoid welding parts already at high hardness.
Can 40CrNiMoA be formed, bent or molded?
Hot forge 1100–1200 °C, finish above 900 °C and normalize afterwards; cold forming is limited to the annealed condition and mild bends only.
What surface finishes work on 40CrNiMoA?
Not anodizable — protect with black oxide, phosphate + oil, Zn or Cd plating, hard chrome, or gas nitriding (surface 550–650 HV); bake 190–220 °C after electroplating high-hardness parts to relieve hydrogen.
40CrNiMoA 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 | 0.37 – 0.44 | 0.4 |
| Si | 0.17 – 0.37 | 0.27 |
| Mn | 0.5 – 0.8 | 0.65 |
| Cr | 0.6 – 0.9 | 0.75 |
| Ni | 1.25 – 1.65 | 1.45 |
| Mo | 0.15 – 0.25 | 0.2 |
| PA grade (high-quality) limit | ≤ 0.03 | — |
| SA grade (high-quality) limit | ≤ 0.03 | — |
| Curesidual | ≤ 0.3 | — |
| Fe | balance | — |
40CrNiMoA Normalized — frequently asked
What is 40CrNiMoA Normalized used for?
40CrNiMoA Normalized is typically used for aircraft landing gear components, drive shafts, industrial axles, gearbox shafts and pinions, heavy-duty crankshafts and high-strength bolts and studs. In short: premium Ni-Cr-Mo bar.
What is the yield strength of 40CrNiMoA Normalized?
40CrNiMoA Normalized has a typical yield strength of 860 MPa (125 ksi) and a tensile strength of 1,280 MPa (186 ksi) — stronger than 89% of steel grades. Strength varies by condition: see the 10 listed tempers.
Is 40CrNiMoA Normalized easy to machine?
Not especially — machinability is rated poor (33/100, worse than 86% of steel grades). Machine in the annealed or ≤32 HRC condition with rigid setups, sharp carbide and generous coolant; above 40 HRC switch to CBN/ceramic turning or grinding, and rough before final temper where possible.
Can 40CrNiMoA Normalized be welded?
Not readily — weldability is rated poor (30/100). High carbon equivalent means preheat 250–350 °C, low-hydrogen filler (e.g. ER100S/ER110S or matching), interpass control and immediate PWHT/re-temper; avoid welding parts already at high hardness.
What surface finishes work on 40CrNiMoA Normalized?
Not anodizable — protect with black oxide, phosphate + oil, Zn or Cd plating, hard chrome, or gas nitriding (surface 550–650 HV); bake 190–220 °C after electroplating high-hardness parts to relieve hydrogen.
Can 40CrNiMoA Normalized be formed, bent or molded?
Hot forge 1100–1200 °C, finish above 900 °C and normalize afterwards; cold forming is limited to the annealed condition and mild bends only.
What is the maximum service temperature of 40CrNiMoA Normalized?
40CrNiMoA Normalized 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 40CrNiMoA Q&T and 40CrNiMoA-HR?
Q&T is the default condition — standard stocked condition: balanced ~1000–1100 MPa strength with high toughness for shafts, gears and high-strength fasteners. HR: cheapest mill condition, bought as forging or machining blank when the shop will heat treat afterwards; properties vary with section and cooling rate. Yield strength is 950 MPa in Q&T versus 620 MPa in HR.
Can FabDigit make parts in 40CrNiMoA Normalized?
Yes — 40CrNiMoA Normalized is available for CNC machining and sheet metal with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- GB/T 3077 Alloy structural steels (2015)
- ASTM A29/A29M and SAE J404 (4340) — ASTM / SAE (2020)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.19 — Fatigue and Fracture — ASM International (1996)
- MMPDS-2023 typical properties for 4340 steel — Battelle/FAA (2023)
- Machinery's Handbook, 31st ed. (machinability ratings) — Industrial Press (2020)
- (40CrNiMoA) — Mysteel / 1688 (2025)
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.