Steel 42CrMoS4 +FP
Heat-treated state
EN 42CrMoS4 · AISI/SAE 4142 · GB 42CrMoS
+FP = treated to ferrite-pearlite structure and hardness range
Best condition for automatic-lathe / high-volume machining of blanks that will be hardened later.
Values for the +FP condition
Other 42CrMoS4 tempers and conditions
42CrMoS4 is listed in 16 conditions; see the grade overview at 42CrMoS4.
- +AC
- Annealed
- +FP
- +N
- Hot Rolled
- +QT750
- +QT800
- +C
- Q&T
- Nitrided
- Induction Hardened
- +CH
- Q&T 28-32 HRC
- +QT1000
- Q&T 32-36 HRC
- +QT1100
Compare all 16 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Spheroidize annealed | Sub-critical/spheroidizing anneal that converts the pearlitic carbides to globular form, giving the softest, most machinable and most cold-formable state of 1.7227 (typically ≤ 241 HB). | 440 | 680 | 22 | 195 HB | 44 W/m·K |
soft annealed (max 241 HB) | Pick for heavy machining/deep-hole work or cold forming before final quench and temper. | 460 | 700 | 18 | 205 HB | — |
+FPThis page Treated to ferrite-pearlite structure and hardness range | Best condition for automatic-lathe / high-volume machining of blanks that will be hardened later. | 500 | 780 | 16 | 16 HRC | 8.5 % IACS |
Normalized | Use for a uniform as-delivered structure in large forgings/bars before machining and final heat treatment. | 530 | 860 | 15 | 24 HRC | — |
as-rolled / as-forged bar | Cheapest stock form for parts that will be fully heat treated after rough machining. | 550 | 900 | 13 | 26 HRC | 8.5 % IACS |
+QT | Largest standard Q&T class for big forged rolls, rams and heavy shafts. | 560 | 825 | 15 | 24 HRC | — |
+QT | Heavy-section Q&T class; accepts the lower core strength from limited hardenability. | 610 | 875 | 14 | 27 HRC | — |
Cold drawn | Choose for close-tolerance bright bar going straight to turning/threading without further heat treatment. | 660 | 820 | 9 | 23 HRC | 8.5 % IACS |
Q&TDefault Quenched and tempered | Default stocked condition: oil-quenched and high-tempered for 900–1100 MPa strength with good toughness in medium sections. | 720 | 1,000 | 13 | 31 HRC | — |
Q&T + gas/plasma nitrided | Pick when wear resistance and fatigue strength of a Q&T core must be boosted without distortion. | 720 | 1,000 | 11 | 58 HRC | 8 % IACS |
Q&T core + induction hardened surface | For journals, splines and gear teeth needing a hard wear surface on a tough Q&T core. | 750 | 1,000 | 10 | 55 HRC | 8 % IACS |
Treatable to specified core hardness range | Through-hardened (oil quench + temper) 1.7227 bar supplied to a guaranteed core hardness band, giving a uniform ~300 HB tempered-martensite core in medium sections. | 800 | 1,000 | 13 | 31 HRC | 42 W/m·K |
Q&T to 28–32 HRC | Common purchased hardness band for machinable shafting, gear blanks and hydraulic parts. | 800 | 960 | 15 | 30 HRC | — |
+QT | Standard class for shafts and spindles 16–40 mm needing ≥750 MPa yield. | 830 | 1,100 | 12 | 34 HRC | — |
Q&T to 32–36 HRC | Higher-strength purchased band for highly loaded shafts, tooling holders and fasteners. | 930 | 1,080 | 13 | 34 HRC | — |
+QT | Highest-strength Q&T class, small bars and fasteners where full through-hardening is achieved. | 980 | 1,180 | 11 | 37 HRC | — |
What is 42CrMoS4 +FP?
42CrMoS4 +FP is 42CrMoS4 heat treated to +FP — best condition for automatic-lathe / high-volume machining of blanks that will be hardened later. 42CrMoS4 +FP has a yield strength of 500 MPa (72.5 ksi) and a tensile strength of 780 MPa (113 ksi) — stronger than 63% of steel grades. Elongation at break is 16% and the elastic modulus is 210 GPa (30.5 Msi). 42CrMoS4 +FP 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). Q&T is the default condition FabDigit quotes; +FP is available on request or by drawing note.
Advantages
- Easy to machine — 68/100, better than 95% of steel grades
- Polishes to a fine finish — 70/100, better than 87% of steel grades
Limitations
- Low fracture toughness — 60 MPa·√m (54.6 ksi·√in), worse than 78% of steel grades
42CrMoS4 +FP properties
Typical room-temperature values for 42CrMoS4 +FP; 23 are specific to this condition. Other listed values are 42CrMoS4 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
42CrMoS4 +FP 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
42CrMoS4 +FP has a yield strength of 500 MPa (72.5 ksi) and a tensile strength of 780 MPa (113 ksi) — stronger than 63% of steel grades. Elongation at break is 16% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
42CrMoS4 +FP is rated for continuous service to 425°C (797 °F). It conducts heat at 44 W/m·K (25.4 BTU/hr·ft·°F), better than 57% of steel grades. Thermal expansion is 11.1 µm/m·K (6.17 µin/in·°F).
Electrical3
42CrMoS4 +FP conducts electricity at 8.5 % IACS, better than 63% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 42CrMoS4 +FP takes about 34 MJ of energy and emits 2.3 kg of CO₂ — more than 82% of steel grades. Typical recycled content is 30%.
Manufacturability6
42CrMoS4 +FP's machinability is good (68/100, better than 95% of steel grades); weldability fair (35/100); formability fair (45/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 42CrMoS4 +FP
Is 42CrMoS4 easy to machine?
Machines best at 200–260 HB; the 0.02–0.04 % S gives short chips and ~10–15 % better tool life than 42CrMo4 — use coated carbide, rigid setups and reduce speeds sharply above 320 HB.
Can 42CrMoS4 be welded?
Weldable only with care: preheat 250–350 °C, low-hydrogen consumables, interpass control and post-weld temper/stress relief below the last tempering temperature; the sulphur raises hot-cracking risk, so 42CrMo4 (non-resulphurised) is preferred for welded assemblies.
Can 42CrMoS4 be formed, bent or molded?
Hot forge 1100–850 °C then slow-cool or normalize; cold forming only in the annealed/+FP state with generous radii — Q&T material is essentially non-formable.
What surface finishes work on 42CrMoS4?
Takes hard chrome, zinc/zinc-nickel, phosphate, black oxide, nitriding and paint; bake at 190–220 °C after acid pickling/plating to avoid hydrogen embrittlement, and expect fine sulphide streaks on high-polish surfaces.
42CrMoS4 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 | 0.38 – 0.45 | 0.42 |
| Si | ≤ 0.4 | 0.25 |
| Mn | 0.6 – 0.9 | 0.75 |
| P | ≤ 0.03 | 0.02 |
| Sdeliberate S addition for machinability (the 'S' in 42CrMoS4) | 0.02 – 0.04 | 0.03 |
| Cr | 0.9 – 1.2 | 1.05 |
| Mo | 0.15 – 0.3 | 0.22 |
| Fe | balance | — |
42CrMoS4 +FP — frequently asked
What is 42CrMoS4 +FP used for?
42CrMoS4 +FP is typically used for shafts, bolts and studs. In short: free-cutting Cr-Mo bar.
What is the yield strength of 42CrMoS4 +FP?
42CrMoS4 +FP has a typical yield strength of 500 MPa (72.5 ksi) and a tensile strength of 780 MPa (113 ksi) — stronger than 63% of steel grades. Strength varies by condition: see the 16 listed tempers.
Is 42CrMoS4 +FP easy to machine?
Reasonably — machinability is rated good (68/100, better than 95% of steel grades). Machines best at 200–260 HB; the 0.02–0.04 % S gives short chips and ~10–15 % better tool life than 42CrMo4 — use coated carbide, rigid setups and reduce speeds sharply above 320 HB.
Can 42CrMoS4 +FP be welded?
With care — weldability is rated fair (35/100). Weldable only with care: preheat 250–350 °C, low-hydrogen consumables, interpass control and post-weld temper/stress relief below the last tempering temperature; the sulphur raises hot-cracking risk, so 42CrMo4 (non-resulphurised) is preferred for welded assemblies.
What surface finishes work on 42CrMoS4 +FP?
Takes hard chrome, zinc/zinc-nickel, phosphate, black oxide, nitriding and paint; bake at 190–220 °C after acid pickling/plating to avoid hydrogen embrittlement, and expect fine sulphide streaks on high-polish surfaces.
Can 42CrMoS4 +FP be formed, bent or molded?
Hot forge 1100–850 °C then slow-cool or normalize; cold forming only in the annealed/+FP state with generous radii — Q&T material is essentially non-formable.
What is the maximum service temperature of 42CrMoS4 +FP?
42CrMoS4 +FP is rated for continuous use to about 425°C (797 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in 42CrMoS4 +FP?
Yes — 42CrMoS4 +FP is available for CNC machining; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.
Sources
- EN 10083-3 Steels for quenching and tempering — Part 3: Alloy steels — CEN (2006)
- EN 10277 / EN 10278 bright steel product standards — CEN (2018)
- GB/T 3077 (42CrMo) — SAC (2015)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels — ASM International (1990)
- ASM Handbook Vol. 19 — Fatigue and Fracture — ASM International (1996)
- 1.7225 / 1.7227 (42CrMo4, 42CrMoS4) engineering steel datasheets — Ovako / Böhler / Deutsche Edelstahlwerke (2022)
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.