Steel 15B30
EN 15B30 · UNS G15301
15B30 is a medium-carbon, high-manganese (1.2–1.5% Mn) structural steel micro-alloyed with boron (0.0005–0.003% B), where the boron sharply raises hardenability and gives near alloy-steel hardening depth at plain-carbon cost.
Values for the HR condition
15B30 tempers and conditions
15B30 is supplied in 8 conditions, soft to hard. HR is the default FabDigit quotes; the values on this page are for it.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
full/subcritical anneal (softest condition) | Use when maximum cold formability, deep drawing or heavy machining precedes final hardening. | 320 | 540 | 26 | 156 HB | — |
HRDefault Hot rolled | Default stock condition for bar, coil and plate that will be formed/machined and then quench-and-tempered. | 380 | 620 | 18 | 179 HB | — |
austenitize ~870 °C, air cool | Pick to homogenize forged or hot-rolled structure and get uniform mid-range strength before final machining. | 390 | 620 | 20 | 179 HB | — |
Cold rolled | Pick for tighter thickness tolerance and better surface on strip that is blanked then heat treated. | 580 | 700 | 11 | 207 HB | — |
Cold drawn | Choose for straight, size-accurate bright bar with higher as-supplied yield strength for machined parts. | 630 | 740 | 10 | 217 HB | — |
quenched and high-temper | Tough, moderately hard condition for shafts, links and structural parts needing impact resistance. | 800 | 950 | 16 | 30 HRC | — |
quenched and medium-temper | Balance of hardness and toughness typical of track links, tillage tools and grade-8 style fasteners. | 1,100 | 1,250 | 12 | 40 HRC | — |
quenched and low-temper | Highest practical hardness for this carbon level — wear plates, harrow discs, cutting edges where impact loads are modest. | 1,330 | 1,550 | 9 | 48 HRC | — |
What is 15B30?
15B30 is a medium-carbon, high-manganese (1.2–1.5% Mn) structural steel micro-alloyed with boron (0.0005–0.003% B), where the boron sharply raises hardenability and gives near alloy-steel hardening depth at plain-carbon cost. It is used for cost-sensitive quench-and-temper parts such as bolts, harrow discs and track shoes, and is stocked hot-rolled, cold-drawn, annealed, normalized and Q&T to 28–32, 38–42 or 45–50 HRC (380 MPa yield, 620 MPa tensile, 179 HB as supplied). High carbon equivalent means welding needs preheat and post-heat, corrosion resistance is that of plain carbon steel, and the boron–nitrogen balance keeps the heat-treat window narrow. 15B30 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). 15B30 has a yield strength of 380 MPa (55.1 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 68% of steel grades. Elongation at break is 18% and the elastic modulus is 205 GPa (29.7 Msi).
What is 15B30 used for?
- Bolts
- Threaded fasteners
- Inserts
15B30 properties
Typical room-temperature values for 15B30-HR; bars are the position among steel grades.
Physical3
15B30 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).
Mechanical13
15B30 has a yield strength of 380 MPa (55.1 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 68% of steel grades. Elongation at break is 18% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
15B30 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 12.2 µm/m·K (6.78 µin/in·°F).
Electrical3
15B30 conducts electricity at 9 % IACS, better than 71% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 86% of steel grades.
Sustainability4
Producing a kilogram of 15B30 takes about 24 MJ of energy and emits 2 kg of CO₂ — less than 97% of steel grades. Typical recycled content is 30%.
Manufacturability7
15B30's machinability is good (55/100, better than 62% of steel grades); weldability fair (45/100); formability fair (50/100).
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. 15B30 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 15B30
Is 15B30 easy to machine?
Machine in the annealed or hot-rolled state (~60% of AISI 1212); carbide tooling and rigid setups above 30 HRC, and expect rapid tool wear beyond 40 HRC.
Can 15B30 be welded?
Weldability is limited by high Mn plus boron — use low-hydrogen consumables, 150–250 °C preheat, controlled interpass and post-weld tempering to avoid HAZ martensite cracking.
Can 15B30 be formed, bent or molded?
Hot forge 1100–1200 °C; cold bending and roll forming are practical only in the annealed/spheroidized condition with generous bend radii, then quench and temper.
Manufacturability
The process limits FabDigit applies to 15B30. Every 15B30 part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
CNC machining
| Machinability | Fair55 / 100 |
|---|---|
| ISO material group | P.2 |
| Cutting speed (rough / finish) | 180 / 210 m/min |
| Minimum wall | 0.8 mm |
| Minimum internal radius | 1 mm |
| Drill depth limit | 5× diameter |
| Best surface (machined / polished) | Ra 1.6 / — |
| Hardenable after machining | No |
Sheet metal
| Formability | Better50 / 100 |
|---|---|
| Weldability | Better45 / 100 |
| Bendable | Yes |
15B30 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 | 0.28 – 0.33 | 0.3 |
| Mnhigh-Mn 15xx series | 1.2 – 1.5 | 1.35 |
| Sitypical killed-steel range (SAE J403 heat analysis) | 0.15 – 0.3 | 0.22 |
| P | ≤ 0.03 | |
| S | ≤ 0.05 | |
| Bboron addition for hardenability; requires Ti/Al N-control | 5×10⁻⁴ – 0 | 0 |
| Fe | balance |
What surface finishes work on 15B30?
No natural corrosion protection — phosphate + oil, black oxide, paint/e-coat, zinc or Zn-Ni plating; bake after plating to relieve hydrogen embrittlement risk above 35 HRC.
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).
Plating
CVD Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel 15B30 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- G15301
How much does 15B30 cost?
15B30 is a standard-cost steel ($$), cheaper than about 71% 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.
15B30 — frequently asked
What is 15B30 used for?
15B30 is typically used for bolts, threaded fasteners and inserts. In short: hot-stamping boron steel.
What is the yield strength of 15B30?
15B30 has a typical yield strength of 380 MPa (55.1 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 68% of steel grades. Strength varies by condition: see the 8 listed tempers.
Is 15B30 easy to machine?
Reasonably — machinability is rated good (55/100, better than 62% of steel grades). Machine in the annealed or hot-rolled state (~60% of AISI 1212); carbide tooling and rigid setups above 30 HRC, and expect rapid tool wear beyond 40 HRC.
Can 15B30 be welded?
With care — weldability is rated fair (45/100). Weldability is limited by high Mn plus boron — use low-hydrogen consumables, 150–250 °C preheat, controlled interpass and post-weld tempering to avoid HAZ martensite cracking.
What surface finishes work on 15B30?
No natural corrosion protection — phosphate + oil, black oxide, paint/e-coat, zinc or Zn-Ni plating; bake after plating to relieve hydrogen embrittlement risk above 35 HRC.
Can 15B30 be formed, bent or molded?
Hot forge 1100–1200 °C; cold bending and roll forming are practical only in the annealed/spheroidized condition with generous bend radii, then quench and temper.
What is the maximum service temperature of 15B30?
15B30 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 15B30-HR and 15B30-CD?
HR is the default condition — default stock condition for bar, coil and plate that will be formed/machined and then quench-and-tempered. CD: choose for straight, size-accurate bright bar with higher as-supplied yield strength for machined parts. Yield strength is 380 MPa in HR versus 630 MPa in CD.
How much does 15B30 cost?
15B30 is a standard-cost steel ($$), cheaper than about 71% 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.
Can FabDigit make parts in 15B30?
Yes — 15B30 is available for CNC machining and sheet metal; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.
Sources
- SAE J403 — Chemical Compositions of SAE Carbon Steels — SAE International (2014)
- SAE J404 / J1268 — Alloy & Hardenability of Boron Steels — SAE International (2019)
- 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)
- ASM Handbook Vol. 16: Machining — ASM International (1989)
- ASTM A29/A29M — Steel Bars, Carbon and Alloy, Hot-Wrought, General Requirements — ASTM (2020)
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.