Steel 4142 · supply condition · default condition
Steel 4142-HR
Properties of the HR condition, compared with the other 4142 tempers.
Cheapest stock form for parts that will be heat treated or rough-machined after purchase.
What is 4142-HR?
4142-HR is 4142 supplied in the HR condition — cheapest stock form for parts that will be heat treated or rough-machined after purchase. 4142-HR has a yield strength of 450 MPa (65.3 ksi) and a tensile strength of 730 MPa (106 ksi) — stronger than 53% of steel grades. Elongation at break is 20% and the elastic modulus is 205 GPa (29.7 Msi). 4142-HR 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).
4142-HR properties
Typical room-temperature values for 4142-HR — 9 properties are specific to this condition; the rest are grade-level values shared by every 4142 temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
4142-HR 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).
Mechanical13
4142-HR has a yield strength of 450 MPa (65.3 ksi) and a tensile strength of 730 MPa (106 ksi) — stronger than 53% of steel grades. Elongation at break is 20% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
4142-HR 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), better than 50% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
4142-HR conducts electricity at 7.8 % IACS, worse than 58% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 4142-HR takes about 29 MJ of energy and emits 2 kg of CO₂ — less than 53% of steel grades. Typical recycled content is 30%.
Manufacturability7
4142-HR's machinability is good (55/100, better than 62% of steel grades); weldability fair (40/100); formability fair (40/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other 4142 tempers and conditions
4142 is also supplied in 11 other conditions. The full side-by-side table is on the 4142 overview.
- HRDefaultCheapest stock form for parts that will be heat treated or rough-machined after purchase.450 MPa yield · 217 HB
- Q&T 45-50 HRCMaximum practical strength/wear from 4142; accept low toughness and difficult machining (grind/EDM).1,450 MPa yield · 48 HRC
- Q&T 38-42 HRCFor wear-loaded pins, spindles and hydraulic components; machining now needs carbide tooling.1,200 MPa yield · 40 HRC
- Q&T 32-36 HRCHigher-strength shafting and tooling bodies where machining is still required after heat treatment.1,010 MPa yield · 34 HRC
- Q&TStandard workhorse condition for shafts and machine parts needing high strength with usable toughness and machinability.960 MPa yield · 32 HRC
- Q&T 28-32 HRCMost commonly specified pre-hard bar hardness band: good strength with straightforward machining.880 MPa yield · 30 HRC
- Q&T 22-26 HRCChoose when hardness must be capped for stress-corrosion / sour-service or maximum toughness.720 MPa yield · 24 HRC
- NormalizedUniform fine-grain structure with medium-high strength; used as a pre-machining or as-supplied condition for forgings.670 MPa yield · 32 HRC
- CDStraight, close-tolerance bright bar with better surface and chip control than hot rolled; use where no further heat treatment is planned.655 MPa yield · 223 HB
- AnnealedSoftest condition; pick for deep machining, cold forming or before final quench and temper.420 MPa yield · 197 HB
Working with 4142-HR
Is 4142 easy to machine?
Machines best at 197–255 HB (annealed or 22–28 HRC); above ~35 HRC use coated carbide, rigid setups and reduced speeds, or grind.
Can 4142 be welded?
Weldable with low-hydrogen consumables but requires 200–320 °C preheat, controlled interpass and post-weld temper below the part's tempering temperature; avoid welding fully hardened sections.
Can 4142 be formed, bent or molded?
Cold form only in the annealed condition with generous radii; most shaping is done hot (1050–1200 °C forging) followed by normalize/anneal.
What surface finishes work on 4142?
No anodizing; protect with black oxide, manganese phosphate, zinc or hard chrome plating (bake to avoid hydrogen embrittlement above ~40 HRC) or nitriding for wear.
4142 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 | 0.4 – 0.45 | 0.42 |
| Mn | 0.75 – 1 | 0.88 |
| Si | 0.15 – 0.35 | 0.25 |
| Cr | 0.8 – 1.1 | 0.95 |
| Mo | 0.15 – 0.25 | 0.2 |
| Pmax, SAE J404 | ≤ 0.04 | — |
| Smax, SAE J404 | ≤ 0.04 | — |
| Fe | balance | — |
4142-HR — frequently asked
What is 4142-HR used for?
4142-HR is typically used for shafts, industrial gears and drive shafts. In short: standard Cr-Mo machining bar.
What is the yield strength of 4142-HR?
4142-HR has a typical yield strength of 450 MPa (65.3 ksi) and a tensile strength of 730 MPa (106 ksi) — stronger than 53% of steel grades. Strength varies by condition: see the 12 listed tempers.
Is 4142-HR easy to machine?
Reasonably — machinability is rated good (55/100, better than 62% of steel grades). Machines best at 197–255 HB (annealed or 22–28 HRC); above ~35 HRC use coated carbide, rigid setups and reduced speeds, or grind.
Can 4142-HR be welded?
With care — weldability is rated fair (40/100). Weldable with low-hydrogen consumables but requires 200–320 °C preheat, controlled interpass and post-weld temper below the part's tempering temperature; avoid welding fully hardened sections.
What surface finishes work on 4142-HR?
No anodizing; protect with black oxide, manganese phosphate, zinc or hard chrome plating (bake to avoid hydrogen embrittlement above ~40 HRC) or nitriding for wear.
Can 4142-HR be formed, bent or molded?
Cold form only in the annealed condition with generous radii; most shaping is done hot (1050–1200 °C forging) followed by normalize/anneal.
What is the maximum service temperature of 4142-HR?
4142-HR 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 4142-HR and 4142-CR?
HR is the default condition — cheapest stock form for parts that will be heat treated or rough-machined after purchase. CR: cold-rolled flat/strip product with tight thickness tolerance and smooth surface; strength from cold work only. Yield strength is 450 MPa in HR versus 670 MPa in CR.
Can FabDigit make parts in 4142-HR?
Yes — 4142-HR 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
- SAE J404 — Chemical Compositions of SAE Alloy Steels — SAE International (2021)
- ASTM A29/A29M — Steel Bars, Carbon and Alloy, Hot-Wrought — ASTM (2020)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.4A — Steel Heat Treating Fundamentals and Processes — ASM International (2013)
- GB/T 3077 — Alloy Structural Steels (42CrMo) — SAC (2015)
- 4140/4142 alloy bar datasheets — Various bar producers/distributors (2023)
- 42CrMo — 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.