Steel 50B46 AUST
Heat-treated state
EN 50B46 · UNS G50461
AUST = austempered
Use for thin springs, clips and tool blades where distortion and quench cracking must be minimized at high hardness.
Values for the AUST condition
Other 50B46 tempers and conditions
50B46 is listed in 11 conditions; see the grade overview at 50B46.
Compare all 11 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Spheroidize Annealed | Pick for cold-headed bolts and screws: softest, most ductile carbide morphology. | 390 | 620 | 25 | 174 HB | 8.5 % IACS |
ADefault Solution annealed | Standard stocked soft condition for machining, cold forming and subsequent quench-and-temper. | 420 | 700 | 20 | 197 HB | — |
Hot rolled | Cheapest mill condition for bar/coil that will be re-heat-treated by the fabricator. | 470 | 800 | 16 | 20 HRC | 8 % IACS |
Normalized | Use to homogenize grain structure after forging before final hardening; note boron steels air-harden more than plain carbon steels. | 560 | 900 | 15 | 26 HRC | 8 % IACS |
Cold drawn | Choose for close-tolerance, bright-finish bar going straight to machining without further heat treatment. | 700 | 830 | 12 | 23 HRC | 8 % IACS |
Q&T 650 °C | Toughest quenched-and-tempered option (~950 MPa) where impact and machinability outrank strength. | 860 | 960 | 20 | 29 HRC | — |
Q&T 540 °C | General machined-component condition (~1150 MPa) with good ductility and impact. | 1,070 | 1,170 | 16 | 36 HRC | — |
AUSTThis page Austempered | Use for thin springs, clips and tool blades where distortion and quench cracking must be minimized at high hardness. | 1,200 | 1,450 | 12 | 44 HRC | 7.5 % IACS |
Q&T 425 °C | Common bolt/spring balance of strength and toughness around 1400 MPa. | 1,310 | 1,430 | 13 | 44 HRC | — |
Q&T 315 °C | High-strength spring/tool condition; keep out of the 260–370 °C temper-embrittlement window if impact matters. | 1,520 | 1,720 | 10 | 50 HRC | — |
Q&T 205 °C | Maximum hardness and wear resistance for tillage tools and springs; very low toughness, avoid stress raisers. | 1,590 | 1,960 | 9 | 54 HRC | — |
What is 50B46 AUST?
50B46 AUST is 50B46 heat treated to AUST — use for thin springs, clips and tool blades where distortion and quench cracking must be minimized at high hardness. 50B46 AUST has a yield strength of 1,200 MPa (174 ksi) and a tensile strength of 1,450 MPa (210 ksi) — stronger than 94% of steel grades. Elongation at break is 12% and the elastic modulus is 205 GPa (29.7 Msi). 50B46 AUST 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). A is the default condition FabDigit quotes; AUST is available on request or by drawing note.
Advantages
- High strength — 1,200 MPa (174 ksi), better than 94% of steel grades
- Polishes to a fine finish — 65/100, better than 78% of steel grades
Limitations
- Limited formability — 10/100, worse than 95% of steel grades
- Difficult to weld — 15/100, worse than 91% of steel grades
- Difficult to machine — 30/100, worse than 89% of steel grades
- Limited ductility — 12%, worse than 84% of steel grades
- Limited service temperature — 300°C (572 °F), worse than 78% of steel grades
50B46 AUST properties
Typical room-temperature values for 50B46 AUST; 22 are specific to this condition. Other listed values are 50B46 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
50B46 AUST 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
50B46 AUST has a yield strength of 1,200 MPa (174 ksi) and a tensile strength of 1,450 MPa (210 ksi) — stronger than 94% of steel grades. Elongation at break is 12% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
50B46 AUST is rated for continuous service to 300°C (572 °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 µm/m·K (6.67 µin/in·°F).
Electrical3
50B46 AUST conducts electricity at 7.5 % IACS, worse than 67% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 86% of steel grades.
Sustainability4
Producing a kilogram of 50B46 AUST takes about 29 MJ of energy and emits 2.1 kg of CO₂ — less than 53% of steel grades. Typical recycled content is 25%.
Manufacturability8
50B46 AUST's machinability is poor (30/100, worse than 89% of steel grades); weldability poor (15/100); formability not recommended (10/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 50B46 AUST
Is 50B46 easy to machine?
Machine in the annealed or spheroidized condition (~60 % of 1212); above 40 HRC switch to carbide/CBN, rigid setups and low feeds, or grind.
Can 50B46 be welded?
Poor weldability — carbon equivalent ≈0.75; if unavoidable use low-hydrogen consumables, 250–350 °C preheat, controlled interpass and immediate post-weld temper.
Can 50B46 be formed, bent or molded?
Cold-head and cold-form only in spheroidize-annealed wire; hot forge 1100–1200 °C and normalize afterwards, then oil quench from 830–860 °C and temper to the target hardness.
What surface finishes work on 50B46?
No inherent corrosion resistance — specify zinc, zinc-nickel or Zn-flake coating, phosphate+oil or black oxide; bake plated parts ≥190 °C/4 h to relieve hydrogen when above ~1000 MPa.
50B46 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 | 0.44 – 0.49 | 0.46 |
| Mn | 0.75 – 1 | 0.88 |
| Si | 0.15 – 0.35 | 0.25 |
| CrSAE 50B46 chromium range (some sources/orders to 0.40–0.60 for 5046-type) | 0.2 – 0.35 | 0.28 |
| Bboron addition for hardenability; effective B requires Ti/Al N-fixing | 5×10⁻⁴ – 0 | 0 |
| P | ≤ 0.04 | — |
| S | ≤ 0.04 | — |
| Fe | balance | — |
50B46 AUST — frequently asked
What is 50B46 AUST used for?
50B46 AUST is typically used for fasteners, springs and clutch parts. In short: through-hardening fastener steel; cheaper than 5146 equivalents; coating required for corrosion.
What is the yield strength of 50B46 AUST?
50B46 AUST has a typical yield strength of 1,200 MPa (174 ksi) and a tensile strength of 1,450 MPa (210 ksi) — stronger than 94% of steel grades. Strength varies by condition: see the 11 listed tempers.
Is 50B46 AUST easy to machine?
Not especially — machinability is rated poor (30/100, worse than 89% of steel grades). Machine in the annealed or spheroidized condition (~60 % of 1212); above 40 HRC switch to carbide/CBN, rigid setups and low feeds, or grind.
Can 50B46 AUST be welded?
Not readily — weldability is rated poor (15/100). Poor weldability — carbon equivalent ≈0.75; if unavoidable use low-hydrogen consumables, 250–350 °C preheat, controlled interpass and immediate post-weld temper.
What surface finishes work on 50B46 AUST?
No inherent corrosion resistance — specify zinc, zinc-nickel or Zn-flake coating, phosphate+oil or black oxide; bake plated parts ≥190 °C/4 h to relieve hydrogen when above ~1000 MPa.
Can 50B46 AUST be formed, bent or molded?
Cold-head and cold-form only in spheroidize-annealed wire; hot forge 1100–1200 °C and normalize afterwards, then oil quench from 830–860 °C and temper to the target hardness.
What is the maximum service temperature of 50B46 AUST?
50B46 AUST 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.
What is the difference between 50B46-A and 50B46-QT205?
A is the default condition — standard stocked soft condition for machining, cold forming and subsequent quench-and-temper. QT205: maximum hardness and wear resistance for tillage tools and springs; very low toughness, avoid stress raisers. Yield strength is 420 MPa in A versus 1,590 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, General Requirements — ASTM (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)
- 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.