Steel 4350 · supply condition · default condition
Steel 4350-HR
Properties of the HR condition, compared with the other 4350 tempers.
Most commonly stocked bar condition — as-rolled blanks for subsequent machining and heat treatment.
What is 4350-HR?
4350-HR is 4350 supplied in the HR condition — most commonly stocked bar condition — as-rolled blanks for subsequent machining and heat treatment. 4350-HR has a yield strength of 650 MPa (94.3 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 79% of steel grades. Elongation at break is 12% and the elastic modulus is 205 GPa (29.7 Msi). 4350-HR 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).
Advantages
- Polishes to a fine finish — 70/100, better than 87% of steel grades
- High strength — 650 MPa (94.3 ksi), better than 79% of steel grades
Limitations
- Limited ductility — 12%, worse than 84% of steel grades
- Difficult to weld — 22/100, worse than 81% of steel grades
- Low fracture toughness — 60 MPa·√m (54.6 ksi·√in), worse than 79% of steel grades
- Limited formability — 22/100, worse than 76% of steel grades
4350-HR properties
Typical room-temperature values for 4350-HR — 10 properties are specific to this condition; the rest are grade-level values shared by every 4350 temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
4350-HR 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).
Mechanical14
4350-HR has a yield strength of 650 MPa (94.3 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 79% of steel grades. Elongation at break is 12% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
4350-HR is rated for continuous service to 400°C (752 °F). It conducts heat at 42 W/m·K (24.3 BTU/hr·ft·°F), worse than 56% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical2
4350-HR has an electrical resistivity of 2.5×10⁻⁷ Ω·m.
Chemical & Environmental2
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 4350-HR takes about 30 MJ of energy and emits 2.2 kg of CO₂ — more than 55% of steel grades. Typical recycled content is 30%.
Manufacturability7
4350-HR's machinability is fair (42/100, worse than 72% of steel grades); weldability poor (22/100); formability poor (22/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other 4350 tempers and conditions
4350 is also supplied in 8 other conditions. The full side-by-side table is on the 4350 overview.
- HRDefaultMost commonly stocked bar condition — as-rolled blanks for subsequent machining and heat treatment.650 MPa yield · 31 HRC
- Q&TStandard high-strength condition: oil quench from ~830 °C and temper 200–450 °C for maximum strength/wear resistance.1,550 MPa yield · 50 HRC
- Q&T 48-52 HRCLow-temper, high-wear condition for tool shanks, dies and highly loaded pins; finish grinding usually required.1,520 MPa yield · 50 HRC
- Q&T 40-45 HRCHigher-temper option when some toughness and machinability must be retained (heavy shafts, gear blanks).1,250 MPa yield · 42 HRC
- CDBright, close-tolerance bar with raised strength — for shafts and parts finished without further heat treatment.900 MPa yield · 33 HRC
- NormalizedUniform fine-grained structure before final hardening; also used where high as-supplied strength is acceptable without Q&T.900 MPa yield · 41 HRC
- AnnealedSoftest supply condition — best for heavy machining, deep boring or cold forming before hardening.520 MPa yield · 235 HB
Working with 4350-HR
Is 4350 easy to machine?
Machine in the annealed or spheroidized state (~50% of AISI 1212); above 40 HRC use carbide/CBN, rigid setups, low speeds or grind to finish.
Can 4350 be welded?
Poor weldability — high carbon equivalent; preheat 300–400 °C, low-hydrogen or matching filler, immediate post-weld temper below the part's tempering temperature, and avoid welding on fully hardened sections.
Can 4350 be formed, bent or molded?
Cold forming only in spheroidized condition and with generous radii; hot forge 1050–1200 °C, finish above 900 °C, then slow-cool or normalize to prevent quench cracking.
What surface finishes work on 4350?
No anodizing; protect with black oxide, manganese phosphate, oil, or zinc/nickel plating — bake at 190–210 °C after acid pickling or electroplating to avoid hydrogen embrittlement. Nitriding and hard chrome are common for wear surfaces.
4350 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 |
|---|---|---|
| CSAE 4350 carbon range | 0.48 – 0.53 | 0.5 |
| Mn | 0.75 – 1 | 0.87 |
| Si | 0.15 – 0.35 | 0.25 |
| Ni | 1.65 – 2 | 1.82 |
| Cr | 0.7 – 0.9 | 0.8 |
| Mo | 0.2 – 0.3 | 0.25 |
| P | ≤ 0.04 | — |
| Smax; lower for aircraft-quality (E-grade) material | ≤ 0.04 | — |
| Fe | balance | — |
4350-HR — frequently asked
What is 4350-HR used for?
4350-HR is typically used for shafts, gears and axles. In short: premium Ni-Cr-Mo bar.
What is the yield strength of 4350-HR?
4350-HR has a typical yield strength of 650 MPa (94.3 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 79% of steel grades. Strength varies by condition: see the 9 listed tempers.
Is 4350-HR easy to machine?
Not especially — machinability is rated fair (42/100, worse than 72% of steel grades). Machine in the annealed or spheroidized state (~50% of AISI 1212); above 40 HRC use carbide/CBN, rigid setups, low speeds or grind to finish.
Can 4350-HR be welded?
Not readily — weldability is rated poor (22/100). Poor weldability — high carbon equivalent; preheat 300–400 °C, low-hydrogen or matching filler, immediate post-weld temper below the part's tempering temperature, and avoid welding on fully hardened sections.
What surface finishes work on 4350-HR?
No anodizing; protect with black oxide, manganese phosphate, oil, or zinc/nickel plating — bake at 190–210 °C after acid pickling or electroplating to avoid hydrogen embrittlement. Nitriding and hard chrome are common for wear surfaces.
Can 4350-HR be formed, bent or molded?
Cold forming only in spheroidized condition and with generous radii; hot forge 1050–1200 °C, finish above 900 °C, then slow-cool or normalize to prevent quench cracking.
What is the maximum service temperature of 4350-HR?
4350-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 4350-HR and 4350-CR?
HR is the default condition — most commonly stocked bar condition — as-rolled blanks for subsequent machining and heat treatment. CR: cold-rolled strip/flat stock for blanked and later hardened parts (springs, blades, wear plates). Yield strength is 650 MPa in HR versus 930 MPa in CR.
Can FabDigit make parts in 4350-HR?
Yes — 4350-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 — General Requirements for Steel Bars, Carbon and Alloy, Hot-Wrought — ASTM (2020)
- SAE J1268 — Hardenability Bands for Carbon and Alloy H Steels — SAE International (2019)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.4 — Heat Treating — ASM International (1991)
- Machinery's Handbook, 31st ed. (machinability ratings) — Industrial Press (2020)
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.