Steel 36CrB4 +A (Annealed)
Heat-treated state
EN 36CrB4
Pick for easiest machining of bar stock before hardening.
Values for the +A condition
Other 36CrB4 tempers and conditions
36CrB4 is listed in 9 conditions; see the grade overview at 36CrB4.
Compare all 9 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Spheroidize annealed | Standard wire-rod/bar condition for cold heading and cold extrusion of bolts before quench and temper. | 370 | 570 | 25 | 175 HB | — |
+AThis page Annealed | Pick for easiest machining of bar stock before hardening. | 380 | 600 | 22 | 185 HB | 45 W/m·K |
Supplied with specified hardenability (Jominy band), for hardening | Order this when the fastener/shaft will be hardened by the part maker and a guaranteed Jominy hardenability band is needed; as-quenched hardness reaches ~52–56 HRC before tempering. | 400 | 620 | 20 | 54 HRC | 8 % IACS |
Hot rolled | Cheapest mill condition for bar/wire rod that will be re-annealed or hardened by the customer. | 500 | 780 | 16 | 21 HRC | 7.9 % IACS |
Spheroidize annealed and cold drawn | Choose for close-tolerance, bright cold-drawn wire/bar that still heads well but arrives dimensionally accurate. | 560 | 680 | 12 | 210 HB | — |
Cold drawn | Bright bar for machined parts where surface finish and straightness matter more than heading ductility. | 700 | 830 | 9 | 24 HRC | 7.8 % IACS |
+QT | Same heat treatment on heavier bar; strength drops with the reduced cooling rate of boron steel. | 700 | 950 | 15 | 29 HRC | 7.9 % IACS |
+QTDefault Quenched and tempered | Default engineering condition: oil/polymer quench from ~860 °C and temper ~540–620 °C for class 10.9 bolts and small shafts. | 850 | 1,050 | 13 | 33 HRC | — |
+QT high-strength temper | Low-temper condition for wear-loaded shafts, pins and high-strength (12.9-type) fasteners; watch hydrogen embrittlement when plating. | 1,100 | 1,300 | 10 | 42 HRC | — |
What is 36CrB4 +A?
36CrB4 +A is 36CrB4 heat treated to +A — pick for easiest machining of bar stock before hardening. 36CrB4 +A has a yield strength of 380 MPa (55.1 ksi) and a tensile strength of 600 MPa (87 ksi) — weaker than 68% of steel grades. Elongation at break is 22% and the elastic modulus is 210 GPa (30.5 Msi). 36CrB4 +A 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). +QT is the default condition FabDigit quotes; +A is available on request or by drawing note.
Limitations
- 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
36CrB4 +A properties
Typical room-temperature values for 36CrB4 +A; 10 are specific to this condition. Other listed values are 36CrB4 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
36CrB4 +A 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
36CrB4 +A has a yield strength of 380 MPa (55.1 ksi) and a tensile strength of 600 MPa (87 ksi) — weaker than 68% of steel grades. Elongation at break is 22% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
36CrB4 +A is rated for continuous service to 300°C (572 °F). It conducts heat at 45 W/m·K (26 BTU/hr·ft·°F), better than 66% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
36CrB4 +A conducts electricity at 7.8 % IACS, worse than 57% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (11/100), worse than 73% of steel grades.
Sustainability4
Producing a kilogram of 36CrB4 +A takes about 29 MJ of energy and emits 2.1 kg of CO₂ — less than 53% of steel grades. Typical recycled content is 30%.
Manufacturability8
36CrB4 +A's machinability is good (60/100, better than 83% of steel grades); weldability poor (30/100); formability good (60/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 36CrB4 +A
Is 36CrB4 easy to machine?
Machine in +A/+AC condition (≈60 % of 1212) with carbide tooling; after Q&T above 33 HRC reduce speeds ~30 % or finish-grind.
Can 36CrB4 be welded?
Restricted weldability (CE ≈ 0.6–0.7): preheat 200–300 °C, low-hydrogen consumables and post-weld temper; boron increases HAZ hardening and cracking risk.
Can 36CrB4 be formed, bent or molded?
Excellent cold heading and cold extrusion in +AC/+AC+C wire; hot forge 1100–850 °C, austenitize 850–880 °C, oil or polymer quench, temper 400–650 °C for the required class.
What surface finishes work on 36CrB4?
No anodizing; use zinc or zinc-nickel electroplate (bake at 200 °C within 4 h above 1000 MPa), zinc-flake coatings, or phosphate-and-oil for cold-formed fasteners.
36CrB4 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 |
|---|---|---|
| CEN 10083-3 / EN 10263-4 | 0.33 – 0.38 | 0.36 |
| Simax for cold-heading quality | ≤ 0.3 | 0.2 |
| Mn | 0.6 – 0.9 | 0.75 |
| P | ≤ 0.03 | 0.02 |
| S0.035 max in some hot-rolled deliveries | ≤ 0.03 | 0.01 |
| Cr | 0.9 – 1.2 | 1.05 |
| Beffective boron; Ti or Al added to fix nitrogen | 8×10⁻⁴ – 0.01 | 0 |
| Titypical nitrogen-fixing addition, producer practice | ≤ 0.05 | 0.03 |
| Fe | balance | — |
36CrB4 +A — frequently asked
What is 36CrB4 +A used for?
36CrB4 +A is typically used for bolts, shafts and fasteners. In short: higher-carbon boron fastener steel; Q&T strength above 1000 MPa; restricted weldability.
What is the yield strength of 36CrB4 +A?
36CrB4 +A has a typical yield strength of 380 MPa (55.1 ksi) and a tensile strength of 600 MPa (87 ksi) — weaker than 68% of steel grades. Strength varies by condition: see the 9 listed tempers.
Is 36CrB4 +A easy to machine?
Reasonably — machinability is rated good (60/100, better than 83% of steel grades). Machine in +A/+AC condition (≈60 % of 1212) with carbide tooling; after Q&T above 33 HRC reduce speeds ~30 % or finish-grind.
Can 36CrB4 +A be welded?
Not readily — weldability is rated poor (30/100). Restricted weldability (CE ≈ 0.6–0.7): preheat 200–300 °C, low-hydrogen consumables and post-weld temper; boron increases HAZ hardening and cracking risk.
What surface finishes work on 36CrB4 +A?
No anodizing; use zinc or zinc-nickel electroplate (bake at 200 °C within 4 h above 1000 MPa), zinc-flake coatings, or phosphate-and-oil for cold-formed fasteners.
Can 36CrB4 +A be formed, bent or molded?
Excellent cold heading and cold extrusion in +AC/+AC+C wire; hot forge 1100–850 °C, austenitize 850–880 °C, oil or polymer quench, temper 400–650 °C for the required class.
What is the maximum service temperature of 36CrB4 +A?
36CrB4 +A 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.
Sources
- EN 10083-3 Steels for quenching and tempering — Alloy steels — CEN (2006)
- EN 10263-4 Steel rod, bars and wire for cold heading and cold extrusion — Steels for quenching and tempering — CEN (2018)
- EN 10084 / EN 10277 (delivery conditions +A, +AC, +C, +H) — CEN (2018)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.19 — Fatigue and Fracture — ASM International (1996)
- Boron-alloyed cold heading steel datasheets (Ovako, voestalpine, Saarstahl) — various steelmakers (2023)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.