Steel 15B41
EN 15B41 · UNS G15411
15B41 is a boron-manganese steel (UNS G15411) with increased carbon for higher-strength fasteners, normally supplied through-hardened.
Reference datasheet — 15B41 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 QT-33-39HRC condition
15B41 tempers and conditions
15B41 is supplied in 9 conditions, soft to hard. QT-33-39HRC is the default FabDigit quotes; the values on this page are for it.
Compare all 9 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Spheroidize annealed | Standard condition for cold-heading and cold-extruding bolt blanks before quench and temper. | 320 | 550 | 30 | 155 HB | — |
Solution annealed | Softest ferrite/pearlite condition for machining or severe forming before hardening. | 350 | 600 | 25 | 170 HB | — |
Hot rolled | Mill-supply condition for bar and coil that will be re-heated, forged or heat treated by the customer. | 415 | 725 | 18 | 210 HB | — |
Normalized | Uniform fine grain and predictable response before hardening; used for forgings. | 480 | 780 | 18 | 225 HB | — |
Cold drawn | Sized, straight bar with raised yield strength for as-machined parts not requiring hardening. | 640 | 760 | 12 | 217 HB | — |
quenched and high-temper (Grade 5 class) | Choose for tough, moderately strong bolts and machine parts where impact matters more than peak strength. | 800 | 950 | 16 | 29 HRC | — |
QT-33-39HRCDefault quenched and tempered (Grade 8 class) | The workhorse fastener condition: full through-hardening plus ≥425 °C temper for 1040 MPa minimum tensile. | 1,030 | 1,160 | 13 | 36 HRC | — |
quenched and low-temper | Pick for wear-loaded parts, self-drilling/track bolts and shafts where strength and abrasion beat toughness. | 1,250 | 1,400 | 10 | 42 HRC | — |
As-quenched | Intermediate process condition only — maximum hardness but brittle; always temper before service. | 1,550 | 2,000 | 2 | 55 HRC | 7 % IACS |
What is 15B41?
15B41 is a boron-manganese steel (UNS G15411) with increased carbon for higher-strength fasteners, normally supplied through-hardened. It is used where a cold-headed part must reach Grade 8 property levels, and is available hot-rolled, annealed, spheroidized, normalized, cold-drawn, as-quenched and quenched-and-tempered to 26–32, 33–39 or 40–45 HRC. Default values are 1030 MPa yield, 1160 MPa tensile, 13 % elongation and 336 HB (36 HRC), with service to 300 °C and machinability rated 40. The high carbon equivalent plus boron makes welding impractical; 15B35 is the lower-strength, easier-processed alternative. 15B41 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). 15B41 has a yield strength of 1,030 MPa (149 ksi) and a tensile strength of 1,160 MPa (168 ksi) — stronger than 93% of steel grades. Elongation at break is 13% and the elastic modulus is 205 GPa (29.7 Msi).
What is 15B41 used for?
- Grade 8 bolts
- High-strength fasteners
- Threaded studs and rods
- Cold-extruded shafts
- Suspension and chassis fastenings
- Wheel studs
Advantages
- High strength — 1,030 MPa (149 ksi), better than 93% of steel grades
Limitations
- Limited formability — 20/100, worse than 80% of steel grades
- Limited ductility — 13%, worse than 78% of steel grades
- Low fracture toughness — 60 MPa·√m (54.6 ksi·√in), worse than 78% of steel grades
- Limited service temperature — 300°C (572 °F), worse than 78% of steel grades
- Difficult to machine — 40/100, worse than 77% of steel grades
15B41 properties
Typical room-temperature values for 15B41-QT-33-39HRC; bars are the position among steel grades.
Physical3
15B41 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).
Mechanical16
15B41 has a yield strength of 1,030 MPa (149 ksi) and a tensile strength of 1,160 MPa (168 ksi) — stronger than 93% of steel grades. Elongation at break is 13% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
15B41 is rated for continuous service to 300°C (572 °F). It conducts heat at 44 W/m·K (25.4 BTU/hr·ft·°F), better than 57% of steel grades. Thermal expansion is 11.7 µm/m·K (6.5 µin/in·°F).
Electrical3
15B41 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 15B41 takes about 26 MJ of energy and emits 2 kg of CO₂ — less than 64% of steel grades. Typical recycled content is 30%.
Manufacturability6
15B41's machinability is fair (40/100, worse than 77% of steel grades); weldability poor (25/100); formability poor (20/100).
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. 15B41 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 15B41
Is 15B41 easy to machine?
Machine in the annealed or spheroidized state (~55 % of 1212); in Q&T at 33–39 HRC use coated carbide, rigid setups and reduced speeds, and finish-grind after hardening for tight tolerances.
Can 15B41 be welded?
Poor — high carbon equivalent plus boron gives a hard, crack-prone HAZ; if welding is unavoidable use low-hydrogen consumables, 200–300 °C preheat and immediate stress-relief/temper, and expect loss of the Q&T properties.
Can 15B41 be formed, bent or molded?
Cold-head and cold-extrude in the spheroidize-annealed condition (excellent CHQ behaviour); hot forge 1100–1220 °C, then normalize before hardening. Austenitize ~840–860 °C, oil or polymer quench, temper 425–540 °C to the required hardness band.
15B41 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 |
|---|---|---|
| Csome listings quote 0.36–0.44 (as SAE 1541) | 0.35 – 0.45 | 0.4 |
| Mn | 1.35 – 1.65 | 1.5 |
| Sikilled-steel silicon range; may be restricted for CHQ wire | 0.15 – 0.35 | 0.22 |
| P | ≤ 0.03 | 0.02 |
| Smax, non-resulfurized | ≤ 0.05 | 0.02 |
| Beffective (soluble) boron; requires Ti/Al nitrogen control | 5×10⁻⁴ – 0 | 0 |
| Fe | balance |
What surface finishes work on 15B41?
No inherent corrosion resistance — zinc, zinc-nickel, phosphate-and-oil or zinc-flake (Dacromet/Geomet) coatings are standard; for parts above ~1000 MPa avoid or bake after electroplating (ASTM F1941/B850) to prevent 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 15B41 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- G15411
How much does 15B41 cost?
15B41 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.
15B41 — frequently asked
What is 15B41 used for?
15B41 is typically used for grade 8 bolts, high-strength fasteners, threaded studs and rods, cold-extruded shafts, suspension and chassis fastenings and wheel studs. In short: grade 8 bolt boron steel; through-hardens to 45 HRC; not for welded assemblies.
What is the yield strength of 15B41?
15B41 has a typical yield strength of 1,030 MPa (149 ksi) and a tensile strength of 1,160 MPa (168 ksi) — stronger than 93% of steel grades. Strength varies by condition: see the 9 listed tempers.
Is 15B41 easy to machine?
Not especially — machinability is rated fair (40/100, worse than 77% of steel grades). Machine in the annealed or spheroidized state (~55 % of 1212); in Q&T at 33–39 HRC use coated carbide, rigid setups and reduced speeds, and finish-grind after hardening for tight tolerances.
Can 15B41 be welded?
Not readily — weldability is rated poor (25/100). Poor — high carbon equivalent plus boron gives a hard, crack-prone HAZ; if welding is unavoidable use low-hydrogen consumables, 200–300 °C preheat and immediate stress-relief/temper, and expect loss of the Q&T properties.
What surface finishes work on 15B41?
No inherent corrosion resistance — zinc, zinc-nickel, phosphate-and-oil or zinc-flake (Dacromet/Geomet) coatings are standard; for parts above ~1000 MPa avoid or bake after electroplating (ASTM F1941/B850) to prevent hydrogen embrittlement.
Can 15B41 be formed, bent or molded?
Cold-head and cold-extrude in the spheroidize-annealed condition (excellent CHQ behaviour); hot forge 1100–1220 °C, then normalize before hardening. Austenitize ~840–860 °C, oil or polymer quench, temper 425–540 °C to the required hardness band.
What is the maximum service temperature of 15B41?
15B41 is rated for continuous use to about 300°C (572 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 15B41 QT-33-39HRC and 15B41-SA?
QT-33-39HRC is the default condition — the workhorse fastener condition: full through-hardening plus ≥425 °C temper for 1040 MPa minimum tensile. SA: standard condition for cold-heading and cold-extruding bolt blanks before quench and temper. Yield strength is 1,030 MPa in QT-33-39HRC versus 320 MPa in SA.
How much does 15B41 cost?
15B41 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 J403 — Chemical Compositions of SAE Carbon Steels (incl. boron grades) — SAE International (2014)
- ASTM A29/A29M — Steel Bars, Carbon and Alloy, Hot-Wrought, General Requirements — ASTM (2020)
- SAE J429 — Mechanical and Material Requirements for Externally Threaded Fasteners — SAE International (2014)
- SAE J1268 — Hardenability Bands for Carbon and Alloy H Steels (15B41H) — SAE International (2019)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.4A — Steel Heat Treating Fundamentals and Processes (boron hardenability) — ASM International (2013)
- GB/T 3077 — Alloy Structural Steels (40MnB comparison grade) — SAC (2015)
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.