Steel M50NiL
M50NiL is a low-carbon, nickel-modified version of the M50 secondary-hardening bearing steel, melted VIM-VAR and case-carburized rather than through-hardened.
Reference datasheet — M50NiL 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 CARB-HT condition
M50NiL tempers and conditions
M50NiL is supplied in 4 conditions, soft to hard. CARB-HT is the default FabDigit quotes; the values on this page are for it.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Supply condition for machining bearing rings and rollers before carburizing. | 620 | 900 | 18 | 21 HRC | — |
CARB-HTDefault Carburized, Hardened & Tempered | Standard aerospace bearing condition: hard wear-resistant case with compressive residual stress over a tough, spall-arresting core. | 1,250 | 1,500 | 12 | 61 HRC | — |
Hardened & Tempered | Use for through-hardened shafts, cages or test coupons where case hardness is not required but high core toughness is. | 1,250 | 1,500 | 13 | 45 HRC | — |
carburize/harden/temper followed by plasma or gas nitriding | Choose when extra surface hardness and scuffing/skid resistance are needed for high-DN or marginally lubricated bearings. | 1,250 | 1,500 | 11 | 66 HRC | 2.9 % IACS |
What is M50NiL?
M50NiL is a low-carbon, nickel-modified version of the M50 secondary-hardening bearing steel, melted VIM-VAR and case-carburized rather than through-hardened. The carburized case reaches about 61 HRC over a tough core with roughly 1250 MPa yield, 1500 MPa tensile and 12% elongation, which is why it is specified for aircraft engine bearings and other high-load rolling element bearings, supplied as bar and forged or ring-rolled blanks. It has no stainless behaviour, is not weldable in practice, machines very poorly (score 8) and is limited to about 315 °C service. Through-hardened M50 is the alternative where core fracture toughness is less critical. M50NiL has a density of 7.89 g/cm³ (0.285 lb/in³), heavier than 93% of steel grades. It melts at 1,400°C (2,552 °F). M50NiL has a yield strength of 1,250 MPa (181 ksi) and a tensile strength of 1,500 MPa (218 ksi) — stronger than 95% of steel grades. Elongation at break is 12% and the elastic modulus is 203 GPa (29.4 Msi).
What is M50NiL used for?
- Aircraft engine mainshaft bearings
- High-load rolling element bearings
- Helicopter transmission bearings
- Gas turbine accessory gearbox bearings
- Carburized bearing rings and rollers
- High-speed spindle bearing races
Advantages
- Polishes to a fine finish — 85/100, better than 99% of steel grades
- High strength — 1,250 MPa (181 ksi), better than 95% of steel grades
Limitations
- Difficult to machine — 8/100, worse than 100% of steel grades
- Difficult to weld — 12/100, worse than 96% of steel grades
- High embodied carbon — 3.8 kg CO₂/kg, worse than 94% of steel grades
- Poor heat conductor — 23 W/m·K (13.3 BTU/hr·ft·°F), worse than 92% of steel grades
- Limited formability — 15/100, worse than 87% of steel grades
M50NiL properties
Typical room-temperature values for M50NiL-CARB-HT; bars are the position among steel grades.
Physical3
M50NiL has a density of 7.89 g/cm³ (0.285 lb/in³), heavier than 93% of steel grades. It melts at 1,400°C (2,552 °F).
Mechanical15
M50NiL has a yield strength of 1,250 MPa (181 ksi) and a tensile strength of 1,500 MPa (218 ksi) — stronger than 95% of steel grades. Elongation at break is 12% and the elastic modulus is 203 GPa (29.4 Msi).
Thermal6
M50NiL is rated for continuous service to 315°C (599 °F). It conducts heat at 23 W/m·K (13.3 BTU/hr·ft·°F), worse than 92% of steel grades. Thermal expansion is 11.4 µm/m·K (6.33 µin/in·°F).
Electrical2
M50NiL has an electrical resistivity of 6×10⁻⁷ Ω·m.
Chemical & Environmental3
Corrosion resistance is poor (18/100), better than 83% of steel grades.
Sustainability4
Producing a kilogram of M50NiL takes about 55 MJ of energy and emits 3.8 kg of CO₂ — more than 94% of steel grades. Typical recycled content is 15%.
Manufacturability6
M50NiL's machinability is not recommended (8/100, worse than 100% of steel grades); weldability not recommended (12/100); formability poor (15/100).
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. M50NiL is highlighted; hover a dot for its name, or open the interactive family chart.
Working with M50NiL
Is M50NiL easy to machine?
Machine all features in the spheroidize-annealed condition with rigid setups and coated carbide at modest speeds; after carburizing and hardening only grinding, honing and superfinishing (or EDM) are practical.
Can M50NiL be welded?
Not weldable in practice — high hardenability and secondary-hardening alloy content give brittle untempered martensite; joints are avoided in bearing components.
Can M50NiL be formed, bent or molded?
Hot forged/ring-rolled from VIM-VAR ingot at roughly 1050–1150 °C with slow cooling and immediate anneal; no cold forming after hardening.
M50NiL 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 |
|---|---|---|
| Clow carbon for case carburizing | 0.11 – 0.15 | 0.13 |
| Mn | 0.15 – 0.35 | 0.25 |
| Si | 0.1 – 0.25 | 0.2 |
| Cr | 4 – 4.25 | 4.1 |
| Nicore toughness / hardenability | 3.2 – 3.6 | 3.4 |
| Mosecondary hardening | 4 – 4.5 | 4.25 |
| Vcarbide former, grain refinement | 1.13 – 1.33 | 1.2 |
| P | ≤ 0.02 | |
| S | ≤ 0.01 | |
| Cu | ≤ 0.1 | |
| Co | ≤ 0.25 | |
| Fe | balance |
What surface finishes work on M50NiL?
Vacuum carburize, harden, deep freeze and triple temper, then grind and superfinish raceways; protect with oil, phosphate or thin black-oxide/DLC since the 4% Cr gives no stainless behaviour.
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 M50NiL in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Also called
- 6278
How much does M50NiL cost?
M50NiL is a high-cost steel ($$$$), pricier than about 78% 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.
M50NiL — frequently asked
What is M50NiL used for?
M50NiL is typically used for aircraft engine mainshaft bearings, high-load rolling element bearings, helicopter transmission bearings, gas turbine accessory gearbox bearings, carburized bearing rings and rollers and high-speed spindle bearing races. In short: carburizing aerospace bearing steel; tough core, 61 HRC case; very difficult to machine.
What is the yield strength of M50NiL?
M50NiL has a typical yield strength of 1,250 MPa (181 ksi) and a tensile strength of 1,500 MPa (218 ksi) — stronger than 95% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is M50NiL easy to machine?
Not especially — machinability is rated not recommended (8/100, worse than 100% of steel grades). Machine all features in the spheroidize-annealed condition with rigid setups and coated carbide at modest speeds; after carburizing and hardening only grinding, honing and superfinishing (or EDM) are practical.
Can M50NiL be welded?
Not readily — weldability is rated not recommended (12/100). Not weldable in practice — high hardenability and secondary-hardening alloy content give brittle untempered martensite; joints are avoided in bearing components.
What surface finishes work on M50NiL?
Vacuum carburize, harden, deep freeze and triple temper, then grind and superfinish raceways; protect with oil, phosphate or thin black-oxide/DLC since the 4% Cr gives no stainless behaviour.
Can M50NiL be formed, bent or molded?
Hot forged/ring-rolled from VIM-VAR ingot at roughly 1050–1150 °C with slow cooling and immediate anneal; no cold forming after hardening.
What is the maximum service temperature of M50NiL?
M50NiL is rated for continuous use to about 315°C (599 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between M50NiL CARB-HT and M50NiL-ANN?
CARB-HT is the default condition — standard aerospace bearing condition: hard wear-resistant case with compressive residual stress over a tough, spall-arresting core. ANN: supply condition for machining bearing rings and rollers before carburizing. Yield strength is 1,250 MPa in CARB-HT versus 620 MPa in ANN.
How much does M50NiL cost?
M50NiL is a high-cost steel ($$$$), pricier than about 78% 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
- AMS 6278 — Steel Bars, Forgings and Tubing, 4.1Cr-3.4Ni-4.2Mo-1.2V, Consumable Electrode Vacuum Melted — SAE International (2018)
- GB/T 3203 (G13Cr4Mo4Ni4V) — SAC (2016)
- ASM Handbook Vol.18 — Friction, Lubrication and Wear Technology (rolling-element bearing steels) — ASM International (2017)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- M50NiL VIM-VAR bearing steel datasheet — Latrobe Specialty Metals / Carpenter Technology (2020)
- NASA Technical Memoranda on M50 and M50NiL bearing fatigue and fracture toughness — NASA Glenn Research Center (1995)
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.