Steel 4615
AISI/SAE 4615 · UNS G46150
4615 is a nickel-molybdenum case-hardening steel from the SAE-AISI 46xx family (UNS G46150, ~1.65-2.00 % Ni, 0.20-0.30 % Mo), supplied as hot-rolled, cold-rolled, cold-drawn, annealed or normalized bar for parts that are carburized after machining.
Values for the HR condition
4615 tempers and conditions
4615 is supplied in 7 conditions, soft to hard. HR is the default FabDigit quotes; the values on this page are for it.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
full anneal, softest condition | Pick for maximum softness and machinability before deep cutting, cold forming or carburizing. | 340 | 520 | 30 | 149 HB | 7.5 % IACS |
HRDefault Hot rolled | Standard stock form for parts that will be machined and then carburized or heat treated. | 350 | 560 | 25 | 163 HB | 7.5 % IACS |
austenitized and air cooled | Use to homogenize forged or hot-worked stock and give a uniform fine-grain core before carburizing. | 380 | 600 | 27 | 174 HB | 7.5 % IACS |
Cold rolled | Thin strip/sheet form with better surface and tighter thickness for stamped parts that are later carburized. | 500 | 620 | 14 | 187 HB | 7.5 % IACS |
Cold drawn | Choose for as-drawn dimensional accuracy, straightness and higher yield in screw-machine work. | 540 | 640 | 15 | 192 HB | 7.5 % IACS |
Quenched and tempered | Direct hardening of the low-carbon core for tough, moderately strong shafts and pins where no case is required. | 680 | 850 | 18 | 25 HRC | — |
carburized, quenched and low-temperature tempered (case 58–62 HRC) | The intended service condition: hard wear-resistant case over a tough Ni–Mo core for gears and cams. | 700 | 900 | 13 | 60 HRC | — |
What is 4615?
4615 is a nickel-molybdenum case-hardening steel from the SAE-AISI 46xx family (UNS G46150, ~1.65-2.00 % Ni, 0.20-0.30 % Mo), supplied as hot-rolled, cold-rolled, cold-drawn, annealed or normalized bar for parts that are carburized after machining. Engineers specify it for exceptional core toughness under a hard case, the reason it is long established in aircraft and industrial gearing. In the default annealed condition it lists 350 MPa yield, 560 MPa tensile, 25 % elongation and 163 HB. It has no corrosion resistance and must be welded before carburizing; 8620 is the lower-cost substitute where nickel-level core toughness is not required. 4615 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). 4615 has a yield strength of 350 MPa (50.8 ksi) and a tensile strength of 560 MPa (81.2 ksi) — weaker than 74% of steel grades. Elongation at break is 25% and the elastic modulus is 205 GPa (29.7 Msi).
What is 4615 used for?
- Gears
- Forged industrial shafts
- Pins
Advantages
- Ductile — tolerates forming and impact — 25%, better than 77% of steel grades
4615 properties
Typical room-temperature values for 4615-HR; bars are the position among steel grades.
Physical3
4615 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
4615 has a yield strength of 350 MPa (50.8 ksi) and a tensile strength of 560 MPa (81.2 ksi) — weaker than 74% of steel grades. Elongation at break is 25% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
4615 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).
Electrical3
4615 conducts electricity at 7.5 % IACS, worse than 67% of steel grades.
Chemical & Environmental2
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 4615 takes about 29 MJ of energy and emits 2.1 kg of CO₂ — less than 53% of steel grades. Typical recycled content is 30%.
Manufacturability7
4615's machinability is good (58/100, better than 75% of steel grades); weldability good (55/100); formability good (55/100).
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. 4615 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 4615
Is 4615 easy to machine?
Machines like other 0.15 %C alloy carburizing steels (~65 % of 1212); normalized stock cuts cleaner than annealed, use sharp tools and positive rake to avoid gumming.
Can 4615 be welded?
Readily arc-welded in the soft condition with low-hydrogen consumables; preheat 100–200 °C on heavy sections and never weld after carburizing.
Can 4615 be formed, bent or molded?
Good cold formability when annealed (bending, upsetting, thread rolling); hot forge 1100–1200 °C and normalize before carburizing.
Manufacturability
The process limits FabDigit applies to 4615. Every 4615 part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
CNC machining
| Machinability | Better58 / 100 |
|---|---|
| ISO material group | P.2 |
| Cutting speed (rough / finish) | 180 / 210 m/min |
| Minimum wall | 0.8 mm |
| Minimum internal radius | 1 mm |
| Drill depth limit | 5× diameter |
| Best surface (machined / polished) | Ra 1.6 / — |
| Hardenable after machining | No |
Sheet metal
| Formability | Better55 / 100 |
|---|---|
| Weldability | Better55 / 100 |
4615 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 | 0.13 – 0.18 | 0.16 |
| Mn | 0.45 – 0.65 | 0.55 |
| Si | 0.15 – 0.35 | 0.25 |
| Ni | 1.65 – 2 | 1.82 |
| Mo | 0.2 – 0.3 | 0.25 |
| P | ≤ 0.04 | |
| S | ≤ 0.04 | |
| Fe | balance |
What surface finishes work on 4615?
No natural corrosion resistance — finish with black oxide, phosphate plus oil, zinc or nickel plating; grind case-hardened surfaces to size after quenching.
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).
Plating
CVD Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel 4615 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- G46150
How much does 4615 cost?
4615 is a standard-cost steel ($$), cheaper than about 71% 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.
4615 — frequently asked
What is 4615 used for?
4615 is typically used for gears, forged industrial shafts and pins. In short: carburizing nickel-moly bar.
What is the yield strength of 4615?
4615 has a typical yield strength of 350 MPa (50.8 ksi) and a tensile strength of 560 MPa (81.2 ksi) — weaker than 74% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is 4615 easy to machine?
Reasonably — machinability is rated good (58/100, better than 75% of steel grades). Machines like other 0.15 %C alloy carburizing steels (~65 % of 1212); normalized stock cuts cleaner than annealed, use sharp tools and positive rake to avoid gumming.
Can 4615 be welded?
Yes — weldability is rated good (55/100). Readily arc-welded in the soft condition with low-hydrogen consumables; preheat 100–200 °C on heavy sections and never weld after carburizing.
What surface finishes work on 4615?
No natural corrosion resistance — finish with black oxide, phosphate plus oil, zinc or nickel plating; grind case-hardened surfaces to size after quenching.
Can 4615 be formed, bent or molded?
Good cold formability when annealed (bending, upsetting, thread rolling); hot forge 1100–1200 °C and normalize before carburizing.
What is the maximum service temperature of 4615?
4615 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 4615-HR and 4615-CD?
HR is the default condition — standard stock form for parts that will be machined and then carburized or heat treated. CD: choose for as-drawn dimensional accuracy, straightness and higher yield in screw-machine work. Yield strength is 350 MPa in HR versus 540 MPa in CD.
How much does 4615 cost?
4615 is a standard-cost steel ($$), cheaper than about 71% 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.
Can FabDigit make parts in 4615?
Yes — 4615 is available for CNC machining and sheet metal; every part is priced by an engineer rather than instantly. 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.4 — Heat Treating (carburizing of Ni-Mo steels) — ASM International (1991)
- ASM Handbook Vol.16 — Machining — ASM International (1989)
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.