Steel 94B30-QT540
Heat-treated state · default condition
EN 94B30 · UNS G94301
QT540 = q&T 540 °C
Most commonly stocked/specified condition: good toughness with ~1000 MPa tensile, still readily machinable.
Values for the QT540 condition
Other 94B30 tempers and conditions
94B30 is listed in 10 conditions; see the grade overview at 94B30.
Compare all 10 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Choose for cold heading, deep machining or wire drawing before quench-and-temper. | 380 | 570 | 24 | 170 HB | — |
Hot rolled | Mill supply condition for bar/coil that will be hot-forged and then heat treated by the part maker. | 430 | 700 | 20 | 15 HRC | 8.2 % IACS |
Normalized | Used to refine forging structure and homogenize before final hardening. | 480 | 760 | 19 | 19 HRC | 8 % IACS |
Cold drawn | Pick when tight size tolerance and a good machined finish are needed prior to heat treatment. | 660 | 760 | 13 | 19 HRC | 8 % IACS |
Q&T 650 °C | Softest Q&T condition — pick for maximum toughness, machining of large sections, or where later welding is planned. | 700 | 830 | 21 | 24 HRC | — |
QT540DefaultThis page Q&T 540 °C | Most commonly stocked/specified condition: good toughness with ~1000 MPa tensile, still readily machinable. | 860 | 990 | 17 | 30 HRC | — |
Q&T 425 °C | Balanced strength/toughness for heavily loaded automotive shafts and Grade 8-class fasteners. | 1,080 | 1,190 | 15 | 37 HRC | — |
Q&T 315 °C | High-strength condition for shafts and fasteners needing more toughness than the 205 °C temper. | 1,270 | 1,400 | 12 | 43 HRC | — |
As-Quenched | Intermediate condition only — full martensite, must be tempered before service to avoid quench cracking. | 1,350 | 1,800 | 5 | 52 HRC | 6.6 % IACS |
Q&T 205 °C | Maximum strength/wear condition for pins, links and wear parts where toughness demand is low. | 1,420 | 1,620 | 10 | 48 HRC | — |
What is 94B30-QT540?
94B30-QT540 is 94B30 heat treated to QT540 — most commonly stocked/specified condition: good toughness with ~1000 MPa tensile, still readily machinable. 94B30-QT540 has a yield strength of 860 MPa (125 ksi) and a tensile strength of 990 MPa (144 ksi) — stronger than 89% of steel grades. Elongation at break is 17% and the elastic modulus is 205 GPa (29.7 Msi). 94B30-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
- High strength — 860 MPa (125 ksi), better than 89% of steel grades
94B30-QT540 properties
Typical room-temperature values for 94B30-QT540; 14 are specific to this condition. Other listed values are 94B30 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
94B30-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).
Mechanical15
94B30-QT540 has a yield strength of 860 MPa (125 ksi) and a tensile strength of 990 MPa (144 ksi) — stronger than 89% of steel grades. Elongation at break is 17% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
94B30-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 12.2 µm/m·K (6.78 µin/in·°F).
Electrical3
94B30-QT540 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 94B30-QT540 takes about 25 MJ of energy and emits 2 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 25%.
Manufacturability7
94B30-QT540's machinability is fair (45/100, worse than 65% of steel grades); weldability fair (35/100); formability fair (35/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 94B30-QT540
Is 94B30 easy to machine?
Machine in the annealed or ≤32 HRC Q&T condition with carbide at moderate speed and heavy positive feed; above 40 HRC use coated carbide/CBN or grind.
Can 94B30 be welded?
Weldable with low-hydrogen consumables only with 200–300 °C preheat and post-weld temper; the martensitic HAZ is crack-prone and boron hardenability makes cooling-rate control critical.
Can 94B30 be formed, bent or molded?
Cold head, upset or bend in the spheroidize-annealed condition; hot forge at 1100–1200 °C and normalize before hardening to restore grain size.
What surface finishes work on 94B30?
No anodizing — protect with zinc or zinc-nickel plating (bake for hydrogen relief above 1000 MPa), manganese phosphate + oil, Zn-flake dip-spin, or paint.
94B30 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 | 0.75 – 1 | 0.88 |
| Si | 0.15 – 0.35 | 0.25 |
| Ni | 0.3 – 0.6 | 0.45 |
| Cr | 0.3 – 0.5 | 0.4 |
| Mo | 0.08 – 0.15 | 0.12 |
| Bhardenability agent; requires Ti/Al nitrogen fixation to stay effective | 5×10⁻⁴ – 0 | 0 |
| P | ≤ 0.04 | — |
| S | ≤ 0.04 | — |
| Fe | balance | — |
94B30-QT540 — frequently asked
What is 94B30-QT540 used for?
94B30-QT540 is typically used for axle shafts, high-strength bolts and structural parts. In short: through-hardening boron grade; 990 MPa quench-and-temper strength; preheat-dependent weldability.
What is the yield strength of 94B30-QT540?
94B30-QT540 has a typical yield strength of 860 MPa (125 ksi) and a tensile strength of 990 MPa (144 ksi) — stronger than 89% of steel grades. Strength varies by condition: see the 10 listed tempers.
Is 94B30-QT540 easy to machine?
Reasonably — machinability is rated fair (45/100, worse than 65% of steel grades). Machine in the annealed or ≤32 HRC Q&T condition with carbide at moderate speed and heavy positive feed; above 40 HRC use coated carbide/CBN or grind.
Can 94B30-QT540 be welded?
With care — weldability is rated fair (35/100). Weldable with low-hydrogen consumables only with 200–300 °C preheat and post-weld temper; the martensitic HAZ is crack-prone and boron hardenability makes cooling-rate control critical.
What surface finishes work on 94B30-QT540?
No anodizing — protect with zinc or zinc-nickel plating (bake for hydrogen relief above 1000 MPa), manganese phosphate + oil, Zn-flake dip-spin, or paint.
Can 94B30-QT540 be formed, bent or molded?
Cold head, upset or bend in the spheroidize-annealed condition; hot forge at 1100–1200 °C and normalize before hardening to restore grain size.
What is the maximum service temperature of 94B30-QT540?
94B30-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 94B30-QT540 and 94B30-QT205?
QT540 is the default condition — most commonly stocked/specified condition: good toughness with ~1000 MPa tensile, still readily machinable. QT205: maximum strength/wear condition for pins, links and wear parts where toughness demand is low. Yield strength is 860 MPa in QT540 versus 1,420 MPa in QT205.
Sources
- SAE J404 — Chemical Compositions of SAE Alloy Steels — SAE International (2021)
- SAE J1268 — Hardenability Bands for Carbon and Alloy H Steels — SAE International (2019)
- 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.4A — Steel Heat Treating Fundamentals and Processes — ASM International (2013)
- SAE J417 — Hardness Tests and Hardness Number Conversions — SAE International (2018)
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.