Steel 15B35
EN 15B35 · UNS G15351
15B35 is a manganese-boron steel (UNS G15351) whose boron addition gives hardenability comparable to leaner alloy steels at carbon-steel cost.
Reference datasheet — 15B35 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 CD condition
15B35 tempers and conditions
15B35 is supplied in 9 conditions, soft to hard. CD 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 |
|---|---|---|---|---|---|---|
Solution annealed | Softest condition; choose for severe cold heading, cold extrusion or deep machining before hardening. | 330 | 560 | 28 | 160 HB | — |
Hot rolled | Mill-supplied stock for forging, hot heading and subsequent heat treatment. | 400 | 655 | 20 | 190 HB | — |
Normalized | Uniform fine-grained structure for forgings prior to machining or as a moderate-strength delivery condition. | 450 | 720 | 18 | 14 HRC | 9.7 % IACS |
CDDefault Cold drawn | Standard stocked fastener and shaft stock: good size tolerance and straightness, ready for cold heading or machining then quench-and-temper. | 620 | 730 | 13 | 217 HB | — |
quenched and tempered (high tempering temperature) | Tough, machinable strength level for shafts, links and forged parts where impact matters more than hardness. | 780 | 900 | 18 | 28 HRC | 44 W/m·K |
quenched and tempered, SAE J429 Grade 8 / ASTM A325 fastener level | The classic 15B35 fastener condition: ≥1040 MPa proof-load capability with acceptable ductility for bolts and screws. | 1,070 | 1,200 | 13 | 36 HRC | — |
Q&T | Salt-bath bainitic treatment for thin sections needing 40–45 HRC with less distortion and better toughness than martensitic Q&T. | 1,150 | 1,350 | 12 | 42 HRC | 8.6 % IACS |
quenched and tempered, high strength | For high-strength links, chain parts and wear-moderate components; ductility and notch tolerance start to drop. | 1,270 | 1,400 | 10 | 43 HRC | — |
quenched and low-temperature tempered (tillage / wear parts) | Hardness-driven condition for plow shares, sweeps, cutting edges and mower blades where abrasion beats toughness. | 1,450 | 1,650 | 8 | 49 HRC | — |
What is 15B35?
15B35 is a manganese-boron steel (UNS G15351) whose boron addition gives hardenability comparable to leaner alloy steels at carbon-steel cost. It is common as fastener wire and small forging stock, with hot-rolled, annealed, normalized and cold-drawn conditions plus quench-and-temper bands from 25–30 HRC up to 46–52 HRC. Default-condition values are 620 MPa yield, 730 MPa tensile, 13 % elongation and 217 HB (96 HRB), with formability rated 55. Boron makes the HAZ hard and crack-sensitive, and there is no corrosion resistance without coating; 10B22 is the softer, more formable alternative. 15B35 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). 15B35 has a yield strength of 620 MPa (89.9 ksi) and a tensile strength of 730 MPa (106 ksi) — stronger than 78% of steel grades. Elongation at break is 13% and the elastic modulus is 205 GPa (29.7 Msi).
What is 15B35 used for?
- high-strength bolts
- studs
- structural fasteners
Advantages
- Low embodied carbon — 1.9 kg CO₂/kg, better than 92% of steel grades
- High strength — 620 MPa (89.9 ksi), better than 78% of steel grades
- High electrical conductivity — 9.5 % IACS, better than 75% of steel grades
Limitations
- Limited ductility — 13%, worse than 78% of steel grades
15B35 properties
Typical room-temperature values for 15B35-CD; bars are the position among steel grades.
Physical3
15B35 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).
Mechanical14
15B35 has a yield strength of 620 MPa (89.9 ksi) and a tensile strength of 730 MPa (106 ksi) — stronger than 78% of steel grades. Elongation at break is 13% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
15B35 is rated for continuous service to 350°C (662 °F). It conducts heat at 46 W/m·K (26.6 BTU/hr·ft·°F), better than 71% of steel grades. Thermal expansion is 11.9 µm/m·K (6.61 µin/in·°F).
Electrical3
15B35 conducts electricity at 9.5 % IACS, better than 75% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 86% of steel grades.
Sustainability4
Producing a kilogram of 15B35 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
15B35's machinability is good (55/100, better than 62% of steel grades); weldability fair (40/100); 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. 15B35 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 15B35
Is 15B35 easy to machine?
Best machined in the spheroidize-annealed or cold-drawn state (~60–65 % of 1212); above 35 HRC use carbide/CBN, rigid setups and reduced feeds.
Can 15B35 be welded?
Boron raises hardenability sharply — preheat 150–250 °C, low-hydrogen consumables and post-weld temper; avoid welding parts already Q&T above 35 HRC.
Can 15B35 be formed, bent or molded?
Excellent hot forging (1050–1200 °C) and good cold heading/extrusion after spheroidize annealing plus phosphate-soap lubrication.
15B35 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 | 0.32 – 0.38 | 0.35 |
| Mn | 0.8 – 1.05 | 0.92 |
| Sibar/forging ranges; may differ for wire rod | 0.15 – 0.35 | 0.25 |
| B0.0005 % min; Ti/Al used to fix N so B stays effective | 5×10⁻⁴ – 0 | 0 |
| P | ≤ 0.04 | |
| S | ≤ 0.04 | |
| Fe | balance |
What surface finishes work on 15B35?
Zinc, zinc-nickel or phosphate-and-oil are standard; bake at 200 °C within 4 h of electroplating parts above ~1040 MPa 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 15B35 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- G15351
How much does 15B35 cost?
15B35 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.
15B35 — frequently asked
What is 15B35 used for?
15B35 is typically used for high-strength bolts, studs and structural fasteners. In short: alloy-grade hardenability, carbon-steel cost; forgeable and cold-headable; mid-range boron fastener steel.
What is the yield strength of 15B35?
15B35 has a typical yield strength of 620 MPa (89.9 ksi) and a tensile strength of 730 MPa (106 ksi) — stronger than 78% of steel grades. Strength varies by condition: see the 9 listed tempers.
Is 15B35 easy to machine?
Reasonably — machinability is rated good (55/100, better than 62% of steel grades). Best machined in the spheroidize-annealed or cold-drawn state (~60–65 % of 1212); above 35 HRC use carbide/CBN, rigid setups and reduced feeds.
Can 15B35 be welded?
With care — weldability is rated fair (40/100). Boron raises hardenability sharply — preheat 150–250 °C, low-hydrogen consumables and post-weld temper; avoid welding parts already Q&T above 35 HRC.
What surface finishes work on 15B35?
Zinc, zinc-nickel or phosphate-and-oil are standard; bake at 200 °C within 4 h of electroplating parts above ~1040 MPa to avoid hydrogen embrittlement.
Can 15B35 be formed, bent or molded?
Excellent hot forging (1050–1200 °C) and good cold heading/extrusion after spheroidize annealing plus phosphate-soap lubrication.
What is the maximum service temperature of 15B35?
15B35 is rated for continuous use to about 350°C (662 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 15B35-CD and 15B35 QT-AC?
CD is the default condition — standard stocked fastener and shaft stock: good size tolerance and straightness, ready for cold heading or machining then quench-and-temper. QT-AC: salt-bath bainitic treatment for thin sections needing 40–45 HRC with less distortion and better toughness than martensitic Q&T. Yield strength is 620 MPa in CD versus 1,150 MPa in QT-AC.
How much does 15B35 cost?
15B35 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 — SAE International (2014)
- SAE J404 / J1268 — Alloy & Boron Steel Chemical Compositions and Hardenability Bands — SAE International (2015)
- ASTM A29/A29M — General Requirements for Steel Bars, Carbon and Alloy, Hot-Wrought — ASTM (2020)
- SAE J429 — Mechanical and Material Requirements for Externally Threaded Fasteners — SAE International (2014)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.4 — Heat Treating (boron 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.