Steel 15MnVB
GB 15MnVB
15MnVB is a low-carbon manganese-vanadium-boron carburizing steel (GB/T 3077) with about 1.4 % Mn, where boron adds hardenability and vanadium restricts grain growth.
Reference datasheet — 15MnVB 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
15MnVB tempers and conditions
15MnVB is supplied in 8 conditions, soft to hard. A 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 |
|---|---|---|---|---|---|---|
ADefault Solution annealed | Standard GB/T 3077 delivery condition — softest, best for machining before carburizing or quench-tempering. | 390 | 620 | 22 | 187 HB | — |
Hot rolled | Cheapest mill condition for stock that will be re-heat-treated after machining. | 440 | 680 | 18 | 13 HRC | 7.8 % IACS |
Normalized | Uniform fine-grain structure with better toughness than as-rolled; common pre-treatment before carburizing. | 470 | 720 | 19 | 16 HRC | 7.8 % IACS |
Cold drawn | Close tolerance, bright finish bar for fastener heading and automatic-lathe parts. | 600 | 730 | 12 | 17 HRC | 7.7 % IACS |
quench + temper for property class 8.8 fasteners | Bolt heat treatment (oil quench + ~500–560 °C temper) meeting ISO 898-1 / GB/T 3098.1 class 8.8. | 720 | 900 | 14 | 28 HRC | — |
860 °C oil quench + 200 °C temper (GB/T 3077 spec condition) | Standard-specification high-strength condition for shafts and pins needing maximum strength with acceptable toughness. | 780 | 1,000 | 13 | 33 HRC | — |
Carburized and hardened | Pick for small/medium gears and splines needing a hard wear-resistant case over a tough Mn-V-B core. | 800 | 1,050 | 11 | 60 HRC | — |
quench + temper for property class 10.9 high-strength bolts | The classic Chinese use of 15MnVB: oil quench + ~420–480 °C temper for 10.9 structural bolts and connection sets. | 990 | 1,100 | 11 | 35 HRC | — |
What is 15MnVB?
15MnVB is a low-carbon manganese-vanadium-boron carburizing steel (GB/T 3077) with about 1.4 % Mn, where boron adds hardenability and vanadium restricts grain growth. It is used for small and medium gears, shafts and pins that need a shallow case over a tough core, and is supplied as hot rolled, annealed, normalized or cold-drawn bar and cold-heading wire. Annealed properties are 390 MPa yield, 620 MPa tensile, 22 % elongation and 187 HB (91 HRB), with service to about 400 °C. Carbon equivalent of 0.5–0.6 makes welding a preheat-and-temper job; 20MnVB gives higher hardened strength. 15MnVB has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,460°C (2,660 °F). 15MnVB has a yield strength of 390 MPa (56.6 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 64% of steel grades. Elongation at break is 22% and the elastic modulus is 210 GPa (30.5 Msi).
What is 15MnVB used for?
- small gears
- shafts
- pins
15MnVB properties
Typical room-temperature values for 15MnVB-A; bars are the position among steel grades.
Physical3
15MnVB has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,460°C (2,660 °F).
Mechanical13
15MnVB has a yield strength of 390 MPa (56.6 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 64% of steel grades. Elongation at break is 22% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
15MnVB is rated for continuous service to 400°C (752 °F). It conducts heat at 44 W/m·K (25.4 BTU/hr·ft·°F), better than 57% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
15MnVB conducts electricity at 7.8 % IACS, worse than 57% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 86% of steel grades.
Sustainability4
Producing a kilogram of 15MnVB takes about 28 MJ of energy and emits 2.1 kg of CO₂ — less than 56% of steel grades. Typical recycled content is 25%.
Manufacturability8
15MnVB's machinability is good (55/100, better than 62% of steel grades); weldability fair (50/100); 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. 15MnVB is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 15MnVB
Is 15MnVB easy to machine?
Machine in the annealed ≤207 HB condition with carbide tooling; the Mn-V structure is gummy at low hardness, so use positive rake, generous feed and coolant, and finish-grind after hardening.
Can 15MnVB be welded?
Weldable with low-hydrogen electrodes but boron plus ~1.4 % Mn gives CE≈0.5–0.6 — preheat 150–250 °C, control interpass, and post-weld temper; avoid welding in the quenched-and-tempered fastener condition.
Can 15MnVB be formed, bent or molded?
Good hot forgeability at 1100–850 °C and adequate cold heading in the spheroidize-annealed state; avoid austenitizing above ~900 °C, which coarsens grain and kills the boron effect.
15MnVB 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 | 0.12 – 0.18 | 0.15 |
| Si | 0.17 – 0.37 | 0.27 |
| Mn | 1.2 – 1.6 | 1.4 |
| Vgrain refiner | 0.07 – 0.12 | 0.09 |
| Bhardenability booster; requires Ti/Al N-fixing | 5×10⁻⁴ – 0 | 0 |
| Crresidual | ≤ 0.3 | |
| Niresidual | ≤ 0.3 | |
| Curesidual | ≤ 0.25 | |
| P | ≤ 0.03 | |
| S | ≤ 0.03 | |
| Fe | balance |
What surface finishes work on 15MnVB?
No corrosion resistance of its own — protect with zinc plating (bake to avoid hydrogen embrittlement above 1000 MPa), phosphate + oil, Dacromet/zinc-flake, or paint; not anodizable.
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
How much does 15MnVB cost?
15MnVB 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.
15MnVB — frequently asked
What is 15MnVB used for?
15MnVB is typically used for small gears, shafts and pins. In short: tough-core carburizing grade; service to 400 °C; most weldable boron gear steel.
What is the yield strength of 15MnVB?
15MnVB has a typical yield strength of 390 MPa (56.6 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 64% of steel grades. Strength varies by condition: see the 8 listed tempers.
Is 15MnVB easy to machine?
Reasonably — machinability is rated good (55/100, better than 62% of steel grades). Machine in the annealed ≤207 HB condition with carbide tooling; the Mn-V structure is gummy at low hardness, so use positive rake, generous feed and coolant, and finish-grind after hardening.
Can 15MnVB be welded?
With care — weldability is rated fair (50/100). Weldable with low-hydrogen electrodes but boron plus ~1.4 % Mn gives CE≈0.5–0.6 — preheat 150–250 °C, control interpass, and post-weld temper; avoid welding in the quenched-and-tempered fastener condition.
What surface finishes work on 15MnVB?
No corrosion resistance of its own — protect with zinc plating (bake to avoid hydrogen embrittlement above 1000 MPa), phosphate + oil, Dacromet/zinc-flake, or paint; not anodizable.
Can 15MnVB be formed, bent or molded?
Good hot forgeability at 1100–850 °C and adequate cold heading in the spheroidize-annealed state; avoid austenitizing above ~900 °C, which coarsens grain and kills the boron effect.
What is the maximum service temperature of 15MnVB?
15MnVB 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 15MnVB-A and 15MnVB-QT109?
A is the default condition — standard GB/T 3077 delivery condition — softest, best for machining before carburizing or quench-tempering. QT109: the classic Chinese use of 15MnVB: oil quench + ~420–480 °C temper for 10.9 structural bolts and connection sets. Yield strength is 390 MPa in A versus 990 MPa in QT109.
How much does 15MnVB cost?
15MnVB 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
- ISO 898-1 Mechanical properties of fasteners made of carbon steel and alloy steel — ISO (2013)
- ASM Handbook Vol.1: Properties and Selection — Irons, Steels, and High-Performance Alloys — ASM International (1990)
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.