Steel 50B60
EN 50B60 · UNS G50601
50B60 (UNS G50601) is a higher-carbon boron-chromium steel in the SAE-AISI alloy family, with the boron addition giving deep hardenability for through-hardened springs and high-strength components.
Reference datasheet — 50B60 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 A condition
50B60 tempers and conditions
50B60 is supplied in 10 conditions, soft to hard. A is the default FabDigit quotes; the values on this page are for it.
Compare all 10 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Spheroidize annealed | Choose for cold-headed fasteners or deep cold upsetting before hardening; lowest hardness and best cold ductility. | 400 | 690 | 22 | 11 HRC | 8.8 % IACS |
ADefault Solution annealed | Standard stock condition for bar that will be machined and then quenched and tempered by the user. | 420 | 750 | 16 | 217 HB | — |
Hot rolled | Lowest-cost mill condition for parts that will be fully heat treated after rough machining or forging. | 530 | 880 | 12 | 25 HRC | 8.6 % IACS |
Normalized | Used to homogenize forgings and refine grain before hardening; note that boron steels air-harden appreciably. | 620 | 1,000 | 11 | 30 HRC | 8.5 % IACS |
Cold drawn | Pick for close-tolerance, bright-surface bar going straight to machining; higher strength but residual stresses and reduced ductility. | 700 | 830 | 10 | 23 HRC | — |
Q&T | Softest quenched-and-tempered condition; used where machining after heat treatment and maximum ductility are needed. | 830 | 930 | 18 | 28 HRC | — |
Q&T | Tough through-hardened condition for shafts, links and machinery parts needing impact capability. | 1,050 | 1,160 | 14 | 36 HRC | — |
Q&T | Classic leaf-spring / torsion-bar condition balancing high elastic limit with usable toughness. | 1,350 | 1,450 | 11 | 44 HRC | — |
Q&T | High-hardness spring and wear condition; avoid 260–370 °C for impact-critical parts (temper embrittlement range). | 1,650 | 1,790 | 9 | 52 HRC | — |
Q&T | Maximum hardness and wear resistance for cutting edges and abrasion parts; very low toughness, brittle in impact. | 1,780 | 2,000 | 8 | 57 HRC | — |
What is 50B60?
50B60 (UNS G50601) is a higher-carbon boron-chromium steel in the SAE-AISI alloy family, with the boron addition giving deep hardenability for through-hardened springs and high-strength components. It is supplied annealed, spheroidized, hot rolled, normalized, cold drawn and quenched and tempered from 205 °C to 650 °C, mainly as bar, flat and coil for spring making. Reference values are 420 MPa yield, 750 MPa tensile, 16 % elongation and 217 HB (96 HRB), with service to 400 °C. Weldability is poor (CE ≈ 0.9, weldability score 25) and the steel has no corrosion resistance; 50B50 is the lower-carbon option when formability matters more than hardness. 50B60 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). 50B60 has a yield strength of 420 MPa (60.9 ksi) and a tensile strength of 750 MPa (109 ksi) — weaker than 53% of steel grades. Elongation at break is 16% and the elastic modulus is 205 GPa (29.7 Msi).
What is 50B60 used for?
- coil and leaf springs
- high-strength bolts
- clutch discs
Advantages
- Low embodied carbon — 1.9 kg CO₂/kg, better than 92% of steel grades
Limitations
- Low fracture toughness — 55 MPa·√m (50.1 ksi·√in), worse than 82% of steel grades
- Difficult to weld — 25/100, worse than 77% of steel grades
50B60 properties
Typical room-temperature values for 50B60-A; bars are the position among steel grades.
Physical3
50B60 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
50B60 has a yield strength of 420 MPa (60.9 ksi) and a tensile strength of 750 MPa (109 ksi) — weaker than 53% of steel grades. Elongation at break is 16% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
50B60 is rated for continuous service to 400°C (752 °F). It conducts heat at 46 W/m·K (26.6 BTU/hr·ft·°F), better than 71% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
50B60 conducts electricity at 8.6 % IACS, better than 66% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 86% of steel grades.
Sustainability4
Producing a kilogram of 50B60 takes about 25 MJ of energy and emits 1.9 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 30%.
Manufacturability7
50B60's machinability is fair (45/100, worse than 65% of steel grades); weldability poor (25/100); 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.
Strength versus weight in the steel family
Yield strength against density for every steel grade FabDigit runs. 50B60 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 50B60
Is 50B60 easy to machine?
Machine in the annealed or spheroidized state (~60 % of 1212); use rigid setups, carbide tooling and moderate speeds — hardness above 40 HRC needs ceramic/CBN or grinding.
Can 50B60 be welded?
Poor weldability (CE ≈ 0.9): preheat 250–350 °C, low-hydrogen consumables, immediate post-weld temper; avoid welding on finished springs.
Can 50B60 be formed, bent or molded?
Hot form or forge at 1050–1200 °C; cold bending only after spheroidize annealing, otherwise expect cracking and heavy springback.
50B60 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 | 0.56 – 0.64 | 0.6 |
| Mn | 0.75 – 1 | 0.88 |
| Si | 0.15 – 0.35 | 0.25 |
| Cr | 0.4 – 0.6 | 0.5 |
| Bhardenability booster; requires Ti/Al nitrogen fixing | 5×10⁻⁴ – 0 | 0 |
| P | ≤ 0.04 | |
| S | ≤ 0.04 | |
| Fe | balance |
What surface finishes work on 50B60?
No natural corrosion resistance — shot peen springs for fatigue life, then phosphate + oil, zinc or Zn-Ni plate (bake 190 °C for hydrogen relief above 40 HRC) or paint.
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 50B60 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- G50601
How much does 50B60 cost?
50B60 is a budget-cost steel ($), cheaper than about 90% 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.
50B60 — frequently asked
What is 50B60 used for?
50B60 is typically used for coil and leaf springs, high-strength bolts and clutch discs. In short: deep-hardening spring steel; higher carbon than 50B50; poor weldability by design.
What is the yield strength of 50B60?
50B60 has a typical yield strength of 420 MPa (60.9 ksi) and a tensile strength of 750 MPa (109 ksi) — weaker than 53% of steel grades. Strength varies by condition: see the 10 listed tempers.
Is 50B60 easy to machine?
Reasonably — machinability is rated fair (45/100, worse than 65% of steel grades). Machine in the annealed or spheroidized state (~60 % of 1212); use rigid setups, carbide tooling and moderate speeds — hardness above 40 HRC needs ceramic/CBN or grinding.
Can 50B60 be welded?
Not readily — weldability is rated poor (25/100). Poor weldability (CE ≈ 0.9): preheat 250–350 °C, low-hydrogen consumables, immediate post-weld temper; avoid welding on finished springs.
What surface finishes work on 50B60?
No natural corrosion resistance — shot peen springs for fatigue life, then phosphate + oil, zinc or Zn-Ni plate (bake 190 °C for hydrogen relief above 40 HRC) or paint.
Can 50B60 be formed, bent or molded?
Hot form or forge at 1050–1200 °C; cold bending only after spheroidize annealing, otherwise expect cracking and heavy springback.
What is the maximum service temperature of 50B60?
50B60 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 50B60-A and 50B60-QT205?
A is the default condition — standard stock condition for bar that will be machined and then quenched and tempered by the user. QT205: maximum hardness and wear resistance for cutting edges and abrasion parts; very low toughness, brittle in impact. Yield strength is 420 MPa in A versus 1,780 MPa in QT205.
How much does 50B60 cost?
50B60 is a budget-cost steel ($), cheaper than about 90% 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
- SAE J404 — Chemical Compositions of SAE Alloy Steels — SAE International (2021)
- SAE J1268 — Hardenability Bands for Boron H-Steels — SAE International (2018)
- 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 — ASM International (1991)
- Low-alloy boron steel property tables (typical Q&T curves) — FabDigit internal compilation (2025)
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.