Steel 40Cr · temper
Steel 40Cr Annealed
Properties of the Annealed condition, compared with the other 40Cr tempers.
Softest condition (≤207 HB per GB/T 3077) for deep machining, cold forming or before final hardening.
What is 40Cr Annealed?
40Cr Annealed is 40Cr in the Annealed temper — softest condition (≤207 HB per GB/T 3077) for deep machining, cold forming or before final hardening. 40Cr Annealed has a yield strength of 400 MPa (58 ksi) and a tensile strength of 680 MPa (98.6 ksi) — weaker than 60% of steel grades. Elongation at break is 22% and the elastic modulus is 211 GPa (30.6 Msi). 40Cr Annealed 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; Annealed is available on request or by drawing note.
Advantages
- Easy to machine — 65/100, better than 93% of steel grades
Limitations
- Low fracture toughness — 55 MPa·√m (50.1 ksi·√in), worse than 83% of steel grades
40Cr Annealed properties
Typical room-temperature values for 40Cr Annealed — 11 properties are specific to this condition; the rest are grade-level values shared by every 40Cr temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
40Cr Annealed 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).
Mechanical16
40Cr Annealed has a yield strength of 400 MPa (58 ksi) and a tensile strength of 680 MPa (98.6 ksi) — weaker than 60% of steel grades. Elongation at break is 22% and the elastic modulus is 211 GPa (30.6 Msi).
Thermal6
40Cr Annealed 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 12.5 µm/m·K (6.94 µin/in·°F).
Electrical3
40Cr Annealed conducts electricity at 8 % IACS, better than 55% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 40Cr Annealed takes about 26 MJ of energy and emits 2 kg of CO₂ — less than 64% of steel grades. Typical recycled content is 35%.
Manufacturability7
40Cr Annealed's machinability is good (65/100, better than 93% of steel grades); weldability fair (50/100); formability good (55/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other 40Cr tempers and conditions
40Cr is also supplied in 9 other conditions. The full side-by-side table is on the 40Cr overview.
- HRDefaultStandard stocked as-rolled bar; buy this and heat treat after rough machining.430 MPa yield · 210 HB
- Q&T 35-40 HRCHigher-strength temper for gears, couplings and wear-loaded parts; toughness and machinability drop.1,050 MPa yield · 38 HRC
- Q&TStandard GB/T 3077 delivery-condition property set; the usual choice for shafts, gears and high-strength bolts.830 MPa yield · 31 HRC
- Q&T 28-32 HRCToughness-first condition for large shafts and parts still to be machined after heat treatment.790 MPa yield · 30 HRC
- CDCold-drawn bright bar: tighter tolerance, better surface and free-er chip than hot rolled.650 MPa yield · 229 HB
- NormalizedAir-cooled from ~860 °C for uniform fine pearlitic structure and predictable machining before Q&T.500 MPa yield · 229 HB
- AnnealedSoftest condition (≤207 HB per GB/T 3077) for deep machining, cold forming or before final hardening.400 MPa yield · 187 HB
Working with 40Cr Annealed
Is 40Cr easy to machine?
Best machined annealed or normalized at 180–230 HB with carbide tooling (~120–180 m/min); above 35 HRC switch to coated carbide/CBN and reduce feed.
Can 40Cr be welded?
Weldable with care only — preheat 200–300 °C, low-hydrogen consumables, and temper immediately after welding; avoid welding fully hardened parts.
Can 40Cr be formed, bent or molded?
Hot forge 1150–850 °C then normalize; cold bending only in the annealed condition with generous radii (≥3t).
What surface finishes work on 40Cr?
No native corrosion protection: use black oxide, manganese phosphate, zinc or hard chrome plating (bake to de-embrittle above ~1000 MPa); polishes well after Q&T.
40Cr 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 | 0.8 – 1.1 | 0.95 |
| Niresidual | ≤ 0.3 | — |
| Curesidual | ≤ 0.25 | — |
| Moresidual, not intentionally added | ≤ 0.1 | — |
| P0.025 max for high-grade quality | ≤ 0.04 | — |
| S0.025 max for high-grade quality | ≤ 0.04 | — |
| Fe | balance | — |
40Cr Annealed — frequently asked
What is 40Cr Annealed used for?
40Cr Annealed is typically used for drive shafts, industrial bolts and crankshafts. In short: chrome alloy machining bar.
What is the yield strength of 40Cr Annealed?
40Cr Annealed has a typical yield strength of 400 MPa (58 ksi) and a tensile strength of 680 MPa (98.6 ksi) — weaker than 60% of steel grades. Strength varies by condition: see the 10 listed tempers.
Is 40Cr Annealed easy to machine?
Reasonably — machinability is rated good (65/100, better than 93% of steel grades). Best machined annealed or normalized at 180–230 HB with carbide tooling (~120–180 m/min); above 35 HRC switch to coated carbide/CBN and reduce feed.
Can 40Cr Annealed be welded?
With care — weldability is rated fair (50/100). Weldable with care only — preheat 200–300 °C, low-hydrogen consumables, and temper immediately after welding; avoid welding fully hardened parts.
What surface finishes work on 40Cr Annealed?
No native corrosion protection: use black oxide, manganese phosphate, zinc or hard chrome plating (bake to de-embrittle above ~1000 MPa); polishes well after Q&T.
Can 40Cr Annealed be formed, bent or molded?
Hot forge 1150–850 °C then normalize; cold bending only in the annealed condition with generous radii (≥3t).
What is the maximum service temperature of 40Cr Annealed?
40Cr Annealed 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 40Cr-HR and 40Cr-IH?
HR is the default condition — standard stocked as-rolled bar; buy this and heat treat after rough machining. IH: choose when only the running surface (journal, spline, gear tooth) needs 50+ HRC wear resistance over a tough core. Yield strength is 430 MPa in HR versus 830 MPa in IH.
Can FabDigit make parts in 40Cr Annealed?
Yes — 40Cr Annealed 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)
- SAE J404 Chemical Compositions of SAE Alloy Steels (5140) — SAE International (2018)
- EN 10083-3 (41Cr4 / 1.7035) — CEN (2006)
- 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)
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.