Steel 15B62
EN 15B62 · UNS G15621
15B62 is a higher-carbon manganese-boron steel (UNS G15621) used for springs and heavy-duty fasteners that need greater through-hardening depth.
Reference datasheet — 15B62 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 HR condition
15B62 tempers and conditions
15B62 is supplied in 10 conditions, soft to hard. HR 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 |
|---|---|---|---|---|---|---|
Solution annealed | Pick for cold heading of fastener blanks, deep machining or cold forming before hardening. | 420 | 700 | 22 | 200 HB | — |
HRDefault Hot rolled | Standard mill supply condition for bar and coil that will be formed and then quenched and tempered by the part maker. | 520 | 930 | 12 | 270 HB | — |
Normalized | Use to refine and homogenise structure after forging, before hardening or machining. | 570 | 1,000 | 11 | 30 HRC | 8 % IACS |
Cold drawn | Choose for close-tolerance bright bar and wire that needs straightness and higher as-supplied yield. | 730 | 860 | 10 | 24 HRC | 8 % IACS |
oil quenched, tempered ~575 °C | Tough medium-hardness setting for heavy-duty bolts, pins and shafts where impact matters more than peak strength. | 980 | 1,120 | 15 | 35 HRC | — |
oil quenched, tempered ~480 °C | Balanced spring/structural setting for leaf springs, clips, tillage tools and 10.9-class fasteners. | 1,250 | 1,400 | 10 | 43 HRC | — |
Austempered | Salt-bath bainitic route for thin springs and clips needing high strength with better ductility and less distortion than martensite + temper. | 1,250 | 1,500 | 11 | 45 HRC | 8 % IACS |
oil quenched, tempered ~400 °C (spring temper) | Classic spring condition — highest usable elastic limit for coil and leaf springs, spring clips and track components. | 1,450 | 1,620 | 8 | 48 HRC | — |
oil quenched, tempered ~300 °C | Wear-oriented setting for plough shares, cultivator points and cutting edges; low toughness, avoid shock and notches. | 1,650 | 1,900 | 6 | 53 HRC | — |
As-quenched | Intermediate condition only — boron gives near-full martensite in sections up to ~25 mm; must be tempered immediately. | 1,700 | 2,200 | 1 | 62 HRC | 7 % IACS |
What is 15B62?
15B62 is a higher-carbon manganese-boron steel (UNS G15621) used for springs and heavy-duty fasteners that need greater through-hardening depth. It is supplied hot-rolled, annealed, normalized, cold-drawn, as-quenched, austempered and quenched-and-tempered in bands from 33–38 HRC to 50–55 HRC. Default-condition values are 520 MPa yield, 930 MPa tensile, 12 % elongation and 270 HB (100 HRB), with formability rated 30. At about 0.60 % C plus boron it is effectively unweldable and must be coated for corrosion protection; 15B48 is the more formable, lower-carbon alternative. 15B62 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). 15B62 has a yield strength of 520 MPa (75.4 ksi) and a tensile strength of 930 MPa (135 ksi) — stronger than 67% of steel grades. Elongation at break is 12% and the elastic modulus is 205 GPa (29.7 Msi).
What is 15B62 used for?
- leaf springs
- heavy fasteners
- washers
Advantages
- Low embodied carbon — 1.9 kg CO₂/kg, better than 92% of steel grades
Limitations
- Limited service temperature — 250°C (482 °F), worse than 85% of steel grades
- Limited ductility — 12%, worse than 84% of steel grades
- Difficult to weld — 20/100, worse than 84% of steel grades
- Low fracture toughness — 60 MPa·√m (54.6 ksi·√in), worse than 78% of steel grades
15B62 properties
Typical room-temperature values for 15B62-HR; bars are the position among steel grades.
Physical3
15B62 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).
Mechanical15
15B62 has a yield strength of 520 MPa (75.4 ksi) and a tensile strength of 930 MPa (135 ksi) — stronger than 67% of steel grades. Elongation at break is 12% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
15B62 is rated for continuous service to 250°C (482 °F). It conducts heat at 45 W/m·K (26 BTU/hr·ft·°F), better than 66% of steel grades. Thermal expansion is 11.5 µm/m·K (6.39 µin/in·°F).
Electrical3
15B62 conducts electricity at 8 % IACS, better than 55% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 86% of steel grades.
Sustainability4
Producing a kilogram of 15B62 takes about 25 MJ of energy and emits 1.9 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 35%.
Manufacturability7
15B62's machinability is fair (42/100, worse than 73% of steel grades); weldability poor (20/100); formability poor (30/100).
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. 15B62 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 15B62
Is 15B62 easy to machine?
Machine in the spheroidise-annealed condition with carbide tooling and rigid setups; above ~40 HRC switch to grinding, CBN or EDM.
Can 15B62 be welded?
Effectively unweldable as a structural joint — 0.60 % C plus boron gives crack-prone martensite; if unavoidable use low-hydrogen consumables, 250–350 °C preheat and immediate stress relief/temper.
Can 15B62 be formed, bent or molded?
Cold head or bend only in the annealed state with generous radii; otherwise hot form at 950–1150 °C and re-harden — do not austenitise above ~950 °C or boron hardenability drops.
15B62 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 15Bxx high-carbon grade | 0.54 – 0.67 | 0.6 |
| Mn | 1 – 1.3 | 1.15 |
| Si | 0.15 – 0.35 | 0.25 |
| Bhardenability booster; requires Ti/Al to fix free nitrogen | 5×10⁻⁴ – 0 | 0 |
| P | ≤ 0.03 | |
| S | ≤ 0.04 | |
| Fe | balance |
What surface finishes work on 15B62?
Shot peen springs for fatigue life, then phosphate + oil, zinc or zinc-flake coating; bake at 190–220 °C within 4 h of electroplating to avoid hydrogen embrittlement.
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 15B62 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- G15621
How much does 15B62 cost?
15B62 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.
15B62 — frequently asked
What is 15B62 used for?
15B62 is typically used for leaf springs, heavy fasteners and washers. In short: highest-carbon boron grade here; spring-capable through-hardening steel; lowest formability, 30/100.
What is the yield strength of 15B62?
15B62 has a typical yield strength of 520 MPa (75.4 ksi) and a tensile strength of 930 MPa (135 ksi) — stronger than 67% of steel grades. Strength varies by condition: see the 10 listed tempers.
Is 15B62 easy to machine?
Not especially — machinability is rated fair (42/100, worse than 73% of steel grades). Machine in the spheroidise-annealed condition with carbide tooling and rigid setups; above ~40 HRC switch to grinding, CBN or EDM.
Can 15B62 be welded?
Not readily — weldability is rated poor (20/100). Effectively unweldable as a structural joint — 0.60 % C plus boron gives crack-prone martensite; if unavoidable use low-hydrogen consumables, 250–350 °C preheat and immediate stress relief/temper.
What surface finishes work on 15B62?
Shot peen springs for fatigue life, then phosphate + oil, zinc or zinc-flake coating; bake at 190–220 °C within 4 h of electroplating to avoid hydrogen embrittlement.
Can 15B62 be formed, bent or molded?
Cold head or bend only in the annealed state with generous radii; otherwise hot form at 950–1150 °C and re-harden — do not austenitise above ~950 °C or boron hardenability drops.
What is the maximum service temperature of 15B62?
15B62 is rated for continuous use to about 250°C (482 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 15B62-HR and 15B62-AQ?
HR is the default condition — standard mill supply condition for bar and coil that will be formed and then quenched and tempered by the part maker. AQ: intermediate condition only — boron gives near-full martensite in sections up to ~25 mm; must be tempered immediately. Yield strength is 520 MPa in HR versus 1,700 MPa in AQ.
How much does 15B62 cost?
15B62 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 J403 / J1268 — Carbon and Alloy Steel Chemical Compositions and Hardenability Bands — SAE International (2019)
- 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 (boron steel hardenability) — 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.