Steel 86B30-QT540
Heat-treated state · default condition
EN 86B30 · UNS G86301
QT540 = q&T 540 °C
Standard commercial quenched and tempered condition, tempered at 540 °C to ~30-32 HRC and 880 MPa yield, for the best strength/toughness compromise in structural and automotive parts.
Values for the QT540 condition
Other 86B30 tempers and conditions
86B30 is listed in 10 conditions; see the grade overview at 86B30.
Compare all 10 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Pick for maximum machinability and cold-forming before final quench and temper. | 375 | 565 | 29 | 156 HB | — |
Normalized | Use to homogenize forgings and give uniform medium strength before machining or final Q&T. | 430 | 650 | 23 | 187 HB | — |
Hot rolled | Cheapest supply form for parts that will be forged and heat treated afterwards. | 450 | 690 | 22 | 13 HRC | 8.1 % IACS |
Cold drawn | Choose for close-tolerance bright bar with raised yield strength and good surface finish. | 590 | 700 | 15 | 17 HRC | 8 % IACS |
Q&T 650 °C | Soft, tough condition for impact-loaded or low-temperature service parts and easier machining. | 690 | 775 | 23 | 22 HRC | — |
QT540DefaultThis page Q&T 540 °C | Standard commercial quenched and tempered condition, tempered at 540 °C to ~30-32 HRC and 880 MPa yield, for the best strength/toughness compromise in structural and automotive parts. | 880 | 970 | 17 | 32 HRC | — |
Induction Hardened & Tempered | Select when a wear-resistant surface with a tough Q&T core is needed on shafts, pins and splines. | 880 | 970 | 12 | 53 HRC | 7.5 % IACS |
Q&T 425 °C | Balance of strength and moderate ductility for shafts and gear blanks. | 1,100 | 1,170 | 13 | 40 HRC | — |
Q&T 315 °C | High-strength condition for wear-loaded links, pins and forged fittings. | 1,240 | 1,380 | 10 | 44 HRC | — |
Q&T 205 °C | Highest strength/hardness condition; use only where toughness demand is low. | 1,360 | 1,550 | 9 | 48 HRC | — |
What is 86B30-QT540?
86B30-QT540 is 86B30 heat treated to QT540 — standard commercial quenched and tempered condition, tempered at 540 °C to ~30-32 HRC and 880 MPa yield, for the best strength/toughness compromise in structural and automotive parts. 86B30-QT540 has a yield strength of 880 MPa (128 ksi) and a tensile strength of 970 MPa (141 ksi) — stronger than 89% of steel grades. Elongation at break is 17% and the elastic modulus is 205 GPa (29.7 Msi). 86B30-QT540 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).
Advantages
- Low embodied carbon — 1.9 kg CO₂/kg, better than 92% of steel grades
- High strength — 880 MPa (128 ksi), better than 89% of steel grades
86B30-QT540 properties
Typical room-temperature values for 86B30-QT540; 11 are specific to this condition. Other listed values are 86B30 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
86B30-QT540 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
86B30-QT540 has a yield strength of 880 MPa (128 ksi) and a tensile strength of 970 MPa (141 ksi) — stronger than 89% of steel grades. Elongation at break is 17% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
86B30-QT540 is rated for continuous service to 400°C (752 °F). It conducts heat at 42 W/m·K (24.3 BTU/hr·ft·°F), worse than 56% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
86B30-QT540 conducts electricity at 7.8 % IACS, worse than 57% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 86B30-QT540 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
86B30-QT540's machinability is fair (45/100, worse than 65% of steel grades); weldability fair (40/100); formability poor (25/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 86B30-QT540
Is 86B30 easy to machine?
Machine in the annealed or normalized state (≈65–70 % of 1212); in Q&T at 30+ HRC use rigid setups, coated carbide, low feed rates and flood coolant.
Can 86B30 be welded?
Carbon equivalent ~0.6–0.7: preheat 200–300 °C, use low-hydrogen consumables and PWHT/temper after welding to avoid cold cracking; the weld HAZ loses boron's hardenability benefit unevenly.
Can 86B30 be formed, bent or molded?
Hot forge 1100–1200 °C with finish above 950 °C; cold forming only in the spheroidized-annealed condition, followed by quench and temper (oil quench from ~860 °C).
What surface finishes work on 86B30?
No inherent corrosion resistance — specify phosphate + oil, zinc plating (with bake-out for hydrogen embrittlement above ~1000 MPa), black oxide or painting; polishes well after hardening.
86B30 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 |
| Mn | 0.7 – 0.9 | 0.8 |
| Si | 0.15 – 0.35 | 0.25 |
| Ni | 0.4 – 0.7 | 0.55 |
| Cr | 0.4 – 0.6 | 0.5 |
| Mo | 0.15 – 0.25 | 0.2 |
| Bboron addition for hardenability; effective (soluble) boron requires N-fixing with Ti/Al | 5×10⁻⁴ – 0 | 0 |
| P | ≤ 0.04 | — |
| S | ≤ 0.04 | — |
| Fe | balance | — |
86B30-QT540 — frequently asked
What is 86B30-QT540 used for?
86B30-QT540 is typically used for structural components, automotive parts and fasteners. In short: boron version of 8630; same hardenability, less alloy; quench-and-temper structural grade.
What is the yield strength of 86B30-QT540?
86B30-QT540 has a typical yield strength of 880 MPa (128 ksi) and a tensile strength of 970 MPa (141 ksi) — stronger than 89% of steel grades. Strength varies by condition: see the 10 listed tempers.
Is 86B30-QT540 easy to machine?
Reasonably — machinability is rated fair (45/100, worse than 65% of steel grades). Machine in the annealed or normalized state (≈65–70 % of 1212); in Q&T at 30+ HRC use rigid setups, coated carbide, low feed rates and flood coolant.
Can 86B30-QT540 be welded?
With care — weldability is rated fair (40/100). Carbon equivalent ~0.6–0.7: preheat 200–300 °C, use low-hydrogen consumables and PWHT/temper after welding to avoid cold cracking; the weld HAZ loses boron's hardenability benefit unevenly.
What surface finishes work on 86B30-QT540?
No inherent corrosion resistance — specify phosphate + oil, zinc plating (with bake-out for hydrogen embrittlement above ~1000 MPa), black oxide or painting; polishes well after hardening.
Can 86B30-QT540 be formed, bent or molded?
Hot forge 1100–1200 °C with finish above 950 °C; cold forming only in the spheroidized-annealed condition, followed by quench and temper (oil quench from ~860 °C).
What is the maximum service temperature of 86B30-QT540?
86B30-QT540 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 86B30-QT540 and 86B30-A?
QT540 is the default condition — standard commercial quenched and tempered condition, tempered at 540 °C to ~30-32 HRC and 880 MPa yield, for the best strength/toughness compromise in structural and automotive parts. A: pick for maximum machinability and cold-forming before final quench and temper. Yield strength is 880 MPa in QT540 versus 375 MPa in A.
Sources
- SAE J404 — Chemical Compositions of SAE Alloy Steels — SAE International (2021)
- SAE J1268 — Hardenability Bands for Boron H-Steels — SAE International (2018)
- ASTM A29/A29M — Steel Bars, Carbon and Alloy, Hot-Wrought — ASTM International (2020)
- 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)
- Machinery's Handbook, 31st ed. — Industrial Press (2020)
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.