Steel 20B46
EN 20B46 · UNS G20461
20B46 is a medium-carbon boron-treated steel (UNS G20461) in which small boron additions give hardenability approaching that of leaner Cr-Mo grades at lower alloy content.
Reference datasheet — 20B46 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 QT30-34 condition
20B46 tempers and conditions
20B46 is supplied in 13 conditions, soft to hard. QT30-34 is the default FabDigit quotes; the values on this page are for it.
Compare all 13 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Softest condition — pick for deep machining, cold heading or before a subsequent hardening cycle. | 375 | 620 | 25 | 179 HB | 48 W/m·K |
Hot rolled | Standard mill delivery form for bar that will be machined and heat treated by the user. | 420 | 720 | 20 | 207 HB | — |
Normalized | Uniform fine-grain structure for consistent machining and predictable response to later quenching. | 470 | 760 | 20 | 217 HB | — |
Cold drawn | Choose for close size tolerance, bright finish and higher as-supplied yield on parts used without heat treatment. | 670 | 790 | 12 | 229 HB | — |
Q&T 22–26 HRC | Toughest Q&T band — for shock-loaded links and shafts where impact energy outranks strength. | 700 | 840 | 20 | 24 HRC | — |
Q&T 28–32 HRC | General machine-shaft band with a good strength/toughness balance and still easy to machine. | 830 | 970 | 18 | 30 HRC | — |
QT30-34Default Q&T 30–34 HRC | Most commonly stocked/ordered condition for boron-steel axles, shafts and tie rods. | 880 | 1,030 | 16 | 32 HRC | — |
Induction hardened | Use where a wear-resistant, compressively stressed skin is needed on a tough shaft (journals, splines, axle shafts). | 880 | 1,030 | 15 | 57 HRC | 7.5 % IACS |
Q&T 33–37 HRC | Higher-strength band for drive shafts and highly loaded links where machining is mostly finished. | 1,000 | 1,120 | 15 | 35 HRC | — |
Q&T 38–42 HRC | High-strength band for grade 8-class fasteners and wear-loaded pins; notch sensitivity rises noticeably. | 1,170 | 1,300 | 13 | 40 HRC | — |
Q&T 45–50 HRC | Wear-oriented low-temper band for plough shares, tines and cutting edges; low ductility, avoid impact-notched designs. | 1,400 | 1,580 | 10 | 48 HRC | — |
Hardened | Order the H version when the part is designed to a Jominy end-quench band rather than to as-delivered mechanical properties. | 1,500 | 1,900 | 8 | 55 HRC | 7.5 % IACS |
As-quenched | Intermediate process state only — maximum hardness but brittle; must be tempered before service. | 1,520 | 1,950 | 2 | 55 HRC | 7 % IACS |
What is 20B46?
20B46 is a medium-carbon boron-treated steel (UNS G20461) in which small boron additions give hardenability approaching that of leaner Cr-Mo grades at lower alloy content. In the default quenched-and-tempered condition it provides 880 MPa yield, 1030 MPa tensile and 16 % elongation at 311 HB (32 HRC), and is stocked as hot-rolled, annealed, normalized, cold-drawn, Q&T (22–50 HRC) and induction-hardened bar for axles, shafts and fasteners. The limits are weldability (carbon equivalent about 0.6–0.7), no inherent corrosion resistance, a 400 °C maximum service temperature and a machinability rating of 45. Where welding or carburizing is central to the design, 41B17 is the nearer choice. 20B46 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). 20B46 has a yield strength of 880 MPa (128 ksi) and a tensile strength of 1,030 MPa (149 ksi) — stronger than 89% of steel grades. Elongation at break is 16% and the elastic modulus is 205 GPa (29.7 Msi).
What is 20B46 used for?
- axle shafts
- structural bolts
- gears
Advantages
- High strength — 880 MPa (128 ksi), better than 89% of steel grades
20B46 properties
Typical room-temperature values for 20B46-QT30-34; bars are the position among steel grades.
Physical3
20B46 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
20B46 has a yield strength of 880 MPa (128 ksi) and a tensile strength of 1,030 MPa (149 ksi) — stronger than 89% of steel grades. Elongation at break is 16% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
20B46 is rated for continuous service to 400°C (752 °F). It conducts heat at 44 W/m·K (25.4 BTU/hr·ft·°F), better than 57% of steel grades. Thermal expansion is 12.2 µm/m·K (6.78 µin/in·°F).
Electrical3
20B46 conducts electricity at 8 % IACS, better than 55% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 20B46 takes about 30 MJ of energy and emits 2.3 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 30%.
Manufacturability6
20B46's machinability is fair (45/100, worse than 65% of steel grades); weldability poor (30/100); formability poor (30/100).
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. 20B46 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 20B46
Is 20B46 easy to machine?
Machine in the annealed/normalized or ≤32 HRC Q&T state with coated carbide, ~120–170 m/min; above 38 HRC switch to rigid setups, negative-rake carbide or CBN and expect much lower tool life.
Can 20B46 be welded?
Weldable only with care — CE ≈ 0.6–0.7 means 200–300 °C preheat, low-hydrogen consumables, controlled interpass and immediate stress relief/temper at 550–650 °C; the HAZ hardens fully because of the boron.
Can 20B46 be formed, bent or molded?
Hot forge at 1100–1200 °C and finish above 900 °C, then normalize; cold heading is practical only in the annealed spheroidized condition, and press-hardened stampings are quenched directly in the die.
20B46 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 |
|---|---|---|
| Cmedium-carbon; sets attainable as-quenched hardness ~55 HRC | 0.44 – 0.49 | 0.46 |
| Mnsources differ slightly on the band; confirm against the mill certificate | 0.75 – 1 | 0.88 |
| Sideoxidation | 0.15 – 0.35 | 0.25 |
| P | ≤ 0.04 | |
| Smax; resulphurised variants are ordered separately for machining | ≤ 0.04 | |
| Beffective (acid-soluble) boron; requires Ti/Al to fix N | 5×10⁻⁴ – 0 | 0 |
| Fe | balance |
What surface finishes work on 20B46?
Requires a coating — phosphate + oil, zinc or zinc-nickel plating, mechanical galvanizing or paint; bake at 200 °C within 4 h of electroplating parts above ~1000 MPa to avoid hydrogen embrittlement.
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 20B46 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- G20461
How much does 20B46 cost?
20B46 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.
20B46 — frequently asked
What is 20B46 used for?
20B46 is typically used for axle shafts, structural bolts and gears. In short: cr-Mo hardenability, less alloy; boron-hardened shaft steel; Q&T to 50 HRC.
What is the yield strength of 20B46?
20B46 has a typical yield strength of 880 MPa (128 ksi) and a tensile strength of 1,030 MPa (149 ksi) — stronger than 89% of steel grades. Strength varies by condition: see the 13 listed tempers.
Is 20B46 easy to machine?
Reasonably — machinability is rated fair (45/100, worse than 65% of steel grades). Machine in the annealed/normalized or ≤32 HRC Q&T state with coated carbide, ~120–170 m/min; above 38 HRC switch to rigid setups, negative-rake carbide or CBN and expect much lower tool life.
Can 20B46 be welded?
Not readily — weldability is rated poor (30/100). Weldable only with care — CE ≈ 0.6–0.7 means 200–300 °C preheat, low-hydrogen consumables, controlled interpass and immediate stress relief/temper at 550–650 °C; the HAZ hardens fully because of the boron.
What surface finishes work on 20B46?
Requires a coating — phosphate + oil, zinc or zinc-nickel plating, mechanical galvanizing or paint; bake at 200 °C within 4 h of electroplating parts above ~1000 MPa to avoid hydrogen embrittlement.
Can 20B46 be formed, bent or molded?
Hot forge at 1100–1200 °C and finish above 900 °C, then normalize; cold heading is practical only in the annealed spheroidized condition, and press-hardened stampings are quenched directly in the die.
What is the maximum service temperature of 20B46?
20B46 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 20B46 QT30-34 and 20B46-AQ?
QT30-34 is the default condition — most commonly stocked/ordered condition for boron-steel axles, shafts and tie rods. AQ: intermediate process state only — maximum hardness but brittle; must be tempered before service. Yield strength is 880 MPa in QT30-34 versus 1,520 MPa in AQ.
How much does 20B46 cost?
20B46 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
- 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 — General Requirements for Steel Bars, Carbon and Alloy, Hot-Wrought — ASTM International (2020)
- ASTM A370 / E140 — Mechanical Testing and Hardness Conversions for Steel — ASTM International (2021)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.4 — Heat Treating (boron hardenability, tempering response) — ASM International (1991)
- Machinery's Handbook (machinability ratings, Q&T bar data) — Industrial Press (2020)
- UNS G20461 alloy record — SAE/ASTM Unified Numbering System (2017)
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.