Steel 42CD4
EN 42CD4 · AISI/SAE 4140
42CD4 is the French AFNOR designation for the chromium-molybdenum engineering steel equivalent to 42CrMo4 and AISI 4140, supplied untreated, spheroidized, annealed, normalized, cold drawn and in a wide range of quenched-and-tempered conditions from +QT section bands to 48–52 HRC, plus nitrided and induction-hardened.
Reference datasheet — 42CD4 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
42CD4 tempers and conditions
42CD4 is supplied in 17 conditions, soft to hard. +QT is the default FabDigit quotes; the values on this page are for it.
- +S
- +A
- +FP
- +U
- +QT 100-250
- +N
- +C
- +QT 40-100
- QT 28-32 HRC
- Nitrided
- Induction Hardened
- +QT
- +QT ≤16
- QT 32-36 HRC
- QT 36-40 HRC
- QT 40-45 HRC
- QT 48-52 HRC
Compare all 17 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Treated to improve shearability | Soft, low-hardness bar for cold shearing of blanks before forging or heat treatment. | 400 | 640 | 24 | 11 HRC | 7.9 % IACS |
Annealed | Best condition for heavy machining, cold forming or deep drilling before final quench and temper. | 415 | 655 | 25 | 197 HB | — |
Treated to ferrite–pearlite structure and hardness range | Controlled soft structure specified when uniform machinability of bar stock matters more than strength. | 440 | 700 | 22 | 16 HRC | 8.4 % IACS |
Hot rolled | Cheapest mill delivery condition when the customer will heat treat the finished part anyway. | 560 | 900 | 16 | 25 HRC | 7.8 % IACS |
+QT, section 100–250 mm | Heavy forgings and large-diameter bar; core toughness stays good but strength drops with mass effect. | 560 | 850 | 17 | 25 HRC | 8 % IACS |
Normalized | Grain refinement and a uniform structure for forgings before machining or final hardening. | 655 | 1,020 | 18 | 32 HRC | — |
Cold drawn | Bright, close-tolerance bar for turned parts where a good surface and straightness are wanted before heat treatment. | 655 | 760 | 14 | 19 HRC | 7.8 % IACS |
+QT, section 40–100 mm | Medium shafts and forgings where mass effect lowers the core properties one class. | 700 | 950 | 15 | 29 HRC | 7.8 % IACS |
Q&T to 28–32 HRC | Common pre-hardened machining condition for shafts, hydraulic parts and mould bases. | 860 | 965 | 16 | 30 HRC | — |
Q&T + gas/plasma nitrided (case ≈0.3–0.6 mm, surface 550–650 HV) | Pick for wear and fatigue-critical shafts, spindles and gears where distortion must stay minimal. | 880 | 1,030 | 13 | 55 HRC | — |
Q&T core + induction-hardened surface (52–58 HRC case) | Selective surface hardening of journals, splines and cam tracks with a tough Q&T core. | 880 | 1,030 | 13 | 55 HRC | 7.5 % IACS |
+QTDefault Quenched and tempered | The standard stocked condition: general-purpose shafts, gears, bolts and tooling needing ~1000 MPa with good toughness. | 900 | 1,030 | 14 | 32 HRC | — |
+QT, section ≤16 mm | Thin bar/wire quenched right through, giving the highest EN 10083-3 property class. | 980 | 1,180 | 11 | 37 HRC | 7.5 % IACS |
Q&T to 32–36 HRC | Higher-strength pre-hard condition for gears, couplings and heavy-duty fasteners. | 1,000 | 1,100 | 14 | 34 HRC | — |
Q&T to 36–40 HRC | Chosen when wear resistance is wanted but through-hardened toughness must be retained. | 1,140 | 1,240 | 12 | 38 HRC | — |
Q&T to 40–45 HRC | High-strength condition for tooling, rock bits and highly loaded pins; machining needs carbide tooling. | 1,310 | 1,420 | 10 | 43 HRC | — |
Q&T low-temper to 48–52 HRC | Maximum hardness/wear resistance for small tools and dies; toughness and weldability are marginal. | 1,580 | 1,720 | 8 | 50 HRC | — |
What is 42CD4?
42CD4 is the French AFNOR designation for the chromium-molybdenum engineering steel equivalent to 42CrMo4 and AISI 4140, supplied untreated, spheroidized, annealed, normalized, cold drawn and in a wide range of quenched-and-tempered conditions from +QT section bands to 48–52 HRC, plus nitrided and induction-hardened. It is the default general-purpose through-hardening steel for shafts, gears, tooling and fasteners in bar, tube and forging form. Default values are 900 MPa yield, 1030 MPa tensile, 14 % elongation, 302 HB (32 HRC) and service to 400 °C, with machinability 50 and weldability 40. It is not corrosion resistant; use 35CD4 where easier welding and forming matter more than strength. 42CD4 has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,416°C (2,581 °F). 42CD4 has a yield strength of 900 MPa (131 ksi) and a tensile strength of 1,030 MPa (149 ksi) — stronger than 90% of steel grades. Elongation at break is 14% and the elastic modulus is 210 GPa (30.5 Msi).
What is 42CD4 used for?
- shafts
- gears
- tooling
- fasteners
Advantages
- High strength — 900 MPa (131 ksi), better than 90% of steel grades
- Polishes to a fine finish — 65/100, better than 78% of steel grades
Limitations
- Limited ductility — 14%, worse than 75% of steel grades
42CD4 properties
Typical room-temperature values for 42CD4-+QT; bars are the position among steel grades.
Physical3
42CD4 has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,416°C (2,581 °F).
Mechanical16
42CD4 has a yield strength of 900 MPa (131 ksi) and a tensile strength of 1,030 MPa (149 ksi) — stronger than 90% of steel grades. Elongation at break is 14% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
42CD4 is rated for continuous service to 400°C (752 °F). It conducts heat at 42.6 W/m·K (24.6 BTU/hr·ft·°F), worse than 51% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
42CD4 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 42CD4 takes about 34 MJ of energy and emits 2.3 kg of CO₂ — more than 82% of steel grades. Typical recycled content is 30%.
Manufacturability7
42CD4's machinability is fair (50/100, worse than 53% of steel grades); weldability fair (40/100); formability poor (30/100).
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. 42CD4 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 42CD4
Is 42CD4 easy to machine?
Machine in the annealed or 28–32 HRC pre-hard condition with coated carbide; above 40 HRC use CBN/ceramic or grind, and allow for higher cutting forces than mild steel.
Can 42CD4 be welded?
Weldable with low-hydrogen consumables but requires 250–350 °C preheat, controlled interpass and post-weld temper below the original tempering temperature to avoid HAZ cracking.
Can 42CD4 be formed, bent or molded?
Hot forge at 1100–850 °C then normalize; cold bending or heading only in the annealed condition, with generous bend radii.
42CD4 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 |
|---|---|---|
| CEN 10083-3 / NF A35-552 | 0.38 – 0.45 | 0.42 |
| Si | ≤ 0.4 | 0.25 |
| Mn | 0.6 – 0.9 | 0.75 |
| P | ≤ 0.03 | 0.02 |
| S0.020–0.040 for free-machining variant 42CrMoS4 | ≤ 0.04 | 0.02 |
| Cr | 0.9 – 1.2 | 1.05 |
| Mo | 0.15 – 0.3 | 0.22 |
| Fe | balance |
What surface finishes work on 42CD4?
No anodizing; protect by black oxide, phosphating, zinc/Zn-Ni plating (bake at 200 °C to de-embrittle above 40 HRC), hard chrome or nitriding — all take a good polish.
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 42CD4 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
How much does 42CD4 cost?
42CD4 is a budget-cost steel ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
42CD4 — frequently asked
What is 42CD4 used for?
42CD4 is typically used for shafts, gears, tooling and fasteners. In short: benchmark Cr-Mo shaft steel; widest range of tempers; higher strength than 35CD4.
What is the yield strength of 42CD4?
42CD4 has a typical yield strength of 900 MPa (131 ksi) and a tensile strength of 1,030 MPa (149 ksi) — stronger than 90% of steel grades. Strength varies by condition: see the 17 listed tempers.
Is 42CD4 easy to machine?
Reasonably — machinability is rated fair (50/100, worse than 53% of steel grades). Machine in the annealed or 28–32 HRC pre-hard condition with coated carbide; above 40 HRC use CBN/ceramic or grind, and allow for higher cutting forces than mild steel.
Can 42CD4 be welded?
With care — weldability is rated fair (40/100). Weldable with low-hydrogen consumables but requires 250–350 °C preheat, controlled interpass and post-weld temper below the original tempering temperature to avoid HAZ cracking.
What surface finishes work on 42CD4?
No anodizing; protect by black oxide, phosphating, zinc/Zn-Ni plating (bake at 200 °C to de-embrittle above 40 HRC), hard chrome or nitriding — all take a good polish.
Can 42CD4 be formed, bent or molded?
Hot forge at 1100–850 °C then normalize; cold bending or heading only in the annealed condition, with generous bend radii.
What is the maximum service temperature of 42CD4?
42CD4 is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does 42CD4 cost?
42CD4 is a budget-cost steel ($), 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 – Alloy steels — CEN (2006)
- NF A35-552 / AFNOR designation 42CD4 — AFNOR (1993)
- SAE J404 Chemical Compositions of SAE Alloy Steels (4140) — SAE International (2021)
- GB/T 3077 (42CrMo) — SAC (2015)
- 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)
- 42CrMo4 / 1.7225 quenched and tempered steel datasheet — Ovako / Böhler (2022)
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.