Steel 37MnB5
EN 37MnB5
37MnB5 (1.5538) is a high-manganese boron steel in the EN 10083 alloy steel family, with the highest manganese and carbon of the MnB fastener series for deep through-hardening.
Reference datasheet — 37MnB5 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 +AC+C condition
37MnB5 tempers and conditions
37MnB5 is supplied in 9 conditions, soft to hard. +AC+C 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 | Choose for maximum cold-heading / cold-extrusion ductility of wire and bar before hardening. | 360 | 560 | 22 | 165 HB | — |
Annealed | General soft-annealed delivery condition for machining and light forming when full spheroidization is not required. | 380 | 600 | 20 | 175 HB | — |
Hot rolled | Mill hot-rolled coil or bar bought for subsequent annealing, hot forging or direct machining. | 450 | 700 | 15 | 210 HB | — |
Normalized | Grain-refined uniform ferrite-pearlite structure for forgings before machining or final hardening. | 480 | 750 | 16 | 220 HB | — |
+AC+CDefault Spheroidized and cold drawn | Standard cold-heading quality wire/bar: spheroidized then lightly drawn to size and surface finish for fastener headers. | 580 | 680 | 10 | 200 HB | — |
Cold drawn | Cold-drawn bar/wire for size tolerance and strength when only limited further cold forming is needed. | 680 | 780 | 8 | 230 HB | — |
+QT | Standard fastener/shaft condition: quench plus ~430–500 °C temper for 1040–1200 MPa with good toughness. | 980 | 1,100 | 12 | 35 HRC | — |
+QT | High-strength condition for socket-head screws and highly loaded links; watch hydrogen embrittlement and notch sensitivity. | 1,150 | 1,300 | 10 | 41 HRC | — |
Hardenability-guaranteed grade, hardened | Order +H when a Jominy hardenability band must be met; properties below are for oil/water quench plus 180–220 °C stress-relief temper. | 1,400 | 1,750 | 6 | 50 HRC | — |
What is 37MnB5?
37MnB5 (1.5538) is a high-manganese boron steel in the EN 10083 alloy steel family, with the highest manganese and carbon of the MnB fastener series for deep through-hardening. It is used for high-strength bolts, studs and shafts formed by cold heading or hot forging and then quenched and tempered to class 10.9 or 12.9; stock is CHQ wire, coil and bar. The default condition gives 580 MPa yield, 680 MPa tensile, 10 % elongation and 200 HB (93 HRB), with a 300 °C service limit. Weldability is low and there is no corrosion resistance; 36MnB4 is the nearest alternative at slightly lower hardenability. 37MnB5 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). 37MnB5 has a yield strength of 580 MPa (84.1 ksi) and a tensile strength of 680 MPa (98.6 ksi) — stronger than 75% of steel grades. Elongation at break is 10% and the elastic modulus is 210 GPa (30.5 Msi).
What is 37MnB5 used for?
- high strength bolts
- shafts
- fasteners
Advantages
- Low embodied carbon — 1.9 kg CO₂/kg, better than 92% of steel grades
- Forms and bends easily — 70/100, better than 86% of steel grades
- High strength — 580 MPa (84.1 ksi), better than 75% of steel grades
Limitations
- Limited ductility — 10%, worse than 91% of steel grades
- Limited service temperature — 300°C (572 °F), worse than 78% of steel grades
37MnB5 properties
Typical room-temperature values for 37MnB5-+AC+C; bars are the position among steel grades.
Physical3
37MnB5 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
37MnB5 has a yield strength of 580 MPa (84.1 ksi) and a tensile strength of 680 MPa (98.6 ksi) — stronger than 75% of steel grades. Elongation at break is 10% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
37MnB5 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 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
37MnB5 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 37MnB5 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
37MnB5's machinability is good (58/100, better than 75% of steel grades); weldability fair (35/100); formability very good (70/100).
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. 37MnB5 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 37MnB5
Is 37MnB5 easy to machine?
Machine in +AC/+A condition (~165–200 HB) with coated carbide, 120–180 m/min; after Q&T above 35 HRC expect heavy tool wear — grind or hard-turn with CBN.
Can 37MnB5 be welded?
Low weldability: CE ≈ 0.6–0.7, boron martensite forms readily — preheat 200–300 °C, low-hydrogen consumables and immediate post-weld tempering; avoid welding on hardened fasteners.
Can 37MnB5 be formed, bent or molded?
Excellent multi-station cold heading and extrusion in the +AC/+AC+C condition with phosphate+soap or polymer lubricant; hot forge 1100–1200 °C but do not overheat above ~1250 °C or boron hardenability is lost.
37MnB5 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 | 0.34 – 0.4 | 0.37 |
| SiSi max for cold-heading quality | ≤ 0.3 | 0.15 |
| Mn | 1.15 – 1.45 | 1.3 |
| P | ≤ 0.03 | |
| S | ≤ 0.03 | |
| Crresidual/optional | ≤ 0.3 | 0.15 |
| Niresidual | ≤ 0.3 | |
| Moresidual | ≤ 0.1 | |
| Curesidual | ≤ 0.25 | |
| Algrain refining / N fixing | 0.02 – 0.06 | 0.04 |
| Tiadded to fix free nitrogen and protect boron | ≤ 0.05 | 0.03 |
| Bhardenability booster | 8×10⁻⁴ – 0.01 | 0 |
| Fe | balance |
What surface finishes work on 37MnB5?
Not anodizable; standard protection is zinc or zinc-nickel electroplate (bake to de-embrittle), zinc flake dip-spin, manganese phosphate + oil, or black oxide.
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 37MnB5 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- EN / DIN / Werkstoff-Nr.
- 1.5538
How much does 37MnB5 cost?
37MnB5 is a budget-cost steel ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
37MnB5 — frequently asked
What is 37MnB5 used for?
37MnB5 is typically used for high strength bolts, shafts and fasteners. In short: deepest-hardening MnB fastener steel; high manganese, boron treated; 10.9/12.9 through-hardened parts.
What is the yield strength of 37MnB5?
37MnB5 has a typical yield strength of 580 MPa (84.1 ksi) and a tensile strength of 680 MPa (98.6 ksi) — stronger than 75% of steel grades. Strength varies by condition: see the 9 listed tempers.
Is 37MnB5 easy to machine?
Reasonably — machinability is rated good (58/100, better than 75% of steel grades). Machine in +AC/+A condition (~165–200 HB) with coated carbide, 120–180 m/min; after Q&T above 35 HRC expect heavy tool wear — grind or hard-turn with CBN.
Can 37MnB5 be welded?
With care — weldability is rated fair (35/100). Low weldability: CE ≈ 0.6–0.7, boron martensite forms readily — preheat 200–300 °C, low-hydrogen consumables and immediate post-weld tempering; avoid welding on hardened fasteners.
What surface finishes work on 37MnB5?
Not anodizable; standard protection is zinc or zinc-nickel electroplate (bake to de-embrittle), zinc flake dip-spin, manganese phosphate + oil, or black oxide.
Can 37MnB5 be formed, bent or molded?
Excellent multi-station cold heading and extrusion in the +AC/+AC+C condition with phosphate+soap or polymer lubricant; hot forge 1100–1200 °C but do not overheat above ~1250 °C or boron hardenability is lost.
What is the maximum service temperature of 37MnB5?
37MnB5 is rated for continuous use to about 300°C (572 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does 37MnB5 cost?
37MnB5 is a budget-cost steel ($), 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
- EN 10263-4 — Steel rod, bars and wire for cold heading and cold extrusion, Part 4: Steels for quenching and tempering — CEN (2018)
- EN 10083-3 — Steels for quenching and tempering, Part 3: Alloy steels — CEN (2006)
- ISO 898-1 — Mechanical properties of fasteners, property classes 8.8/10.9/12.9 — ISO (2013)
- GB/T 6478 / GB/T 3077 — / (ML37MnB analogue) — SAC (2015)
- ASM Handbook Vol.1: Properties and Selection — Irons, Steels, and High-Performance Alloys (boron steels) — ASM International (1990)
- ASM Handbook Vol.4A: Steel Heat Treating Fundamentals (boron hardenability) — ASM International (2013)
- Cold-heading boron steel wire rod datasheets (37MnB5 / 38MnB5) — European and Asian wire rod producers (2022)
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.