Steel 4047
AISI/SAE 4047 · UNS G40470
4047 is the highest-carbon grade in the plain molybdenum 40xx series (UNS G40470) and is used mainly for high-strength fasteners after quench and temper.
Reference datasheet — 4047 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 A condition
4047 tempers and conditions
4047 is supplied in 11 conditions, soft to hard. A is the default FabDigit quotes; the values on this page are for it.
Compare all 11 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Spheroidize annealed | Pick for cold-headed fastener blanks where maximum ductility at this carbon level is needed. | 360 | 570 | 26 | 170 HB | 8 % IACS |
ADefault Solution annealed | Choose for rough machining, cold sawing and stock that will be heat treated after fabrication. | 400 | 620 | 22 | 185 HB | — |
Hot rolled | Cheapest mill condition for stock that will be normalized or quenched and tempered later. | 430 | 730 | 19 | 17 HRC | 7.8 % IACS |
Normalized | Use to refine grain and homogenize forgings before hardening, or as a moderate-strength as-supplied condition. | 510 | 810 | 19 | 21 HRC | 7.8 % IACS |
Cold drawn | Choose for close-tolerance bright bar with higher yield strength and better surface finish than hot rolled. | 650 | 760 | 12 | 19 HRC | 7.8 % IACS |
Q&T 650 °C | Softest Q&T condition — pick when toughness, machinability or sour-service hardness caps (<22–25 HRC) matter more than strength. | 740 | 860 | 22 | 24 HRC | — |
Induction hardened & tempered surface | Use when a wear-resistant 55+ HRC case with a tough core is needed on shafts, pins or gear journals. | 900 | 1,050 | 14 | 56 HRC | 7.2 % IACS |
Q&T 540 °C | General-purpose quenched-and-tempered condition: good strength with usable toughness and machinability. | 950 | 1,050 | 18 | 33 HRC | — |
Q&T 425 °C | Balanced high-strength condition for shafts, studs and Grade 8-class fasteners. | 1,170 | 1,290 | 14 | 41 HRC | — |
Q&T 315 °C | High-hardness spring/tool-like condition; keep out of the 260–370 °C blue-brittleness zone for impact-loaded parts. | 1,330 | 1,580 | 11 | 47 HRC | — |
Q&T 205 °C | Maximum hardness/wear condition for small sections; very low toughness, avoid where impact or notches exist. | 1,450 | 1,830 | 9 | 51 HRC | — |
What is 4047?
4047 is the highest-carbon grade in the plain molybdenum 40xx series (UNS G40470) and is used mainly for high-strength fasteners after quench and temper. It is available annealed, spheroidize-annealed, hot-rolled, normalized, cold-drawn and in tempered conditions from QT205 through QT650, with an intercritically quenched-and-tempered option; the default condition gives 400 MPa yield, 620 MPa tensile, 22 % elongation and 185 HB (90 HRB). Machinability rates 55 and formability only 35, and weldability is poor (CE ≈ 0.65–0.70). For easier fabrication at similar strength, 4140 or 4137 are the common alternatives. 4047 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). 4047 has a yield strength of 400 MPa (58 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 60% of steel grades. Elongation at break is 22% and the elastic modulus is 205 GPa (29.7 Msi).
What is 4047 used for?
- high-strength bolts
- springs
- fasteners
Limitations
- Low fracture toughness — 60 MPa·√m (54.6 ksi·√in), worse than 78% of steel grades
4047 properties
Typical room-temperature values for 4047-A; bars are the position among steel grades.
Physical3
4047 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
4047 has a yield strength of 400 MPa (58 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 60% of steel grades. Elongation at break is 22% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
4047 is rated for continuous service to 400°C (752 °F). It conducts heat at 43 W/m·K (24.8 BTU/hr·ft·°F), better than 51% of steel grades. Thermal expansion is 12.2 µm/m·K (6.78 µin/in·°F).
Electrical3
4047 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 4047 takes about 29 MJ of energy and emits 2 kg of CO₂ — less than 53% of steel grades. Typical recycled content is 30%.
Manufacturability6
4047's machinability is good (55/100, better than 62% of steel grades); weldability poor (28/100); formability fair (35/100).
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. 4047 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 4047
Is 4047 easy to machine?
Machine in the annealed or ≤32 HRC condition with carbide tooling and rigid setups; above 40 HRC switch to CBN/ceramic or grind, and expect roughly half the tool life of 1045.
Can 4047 be welded?
Difficult — CE ≈ 0.65–0.70; preheat 300–400 °C, use low-hydrogen consumables, keep interpass temperature and temper immediately after welding to avoid hydrogen and quench cracking.
Can 4047 be formed, bent or molded?
Cold form only in the spheroidize-annealed condition (upsetting of fastener blanks); otherwise hot forge at 1050–1200 °C and normalize afterwards.
4047 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 |
|---|---|---|
| Chighest carbon of the 40xx series | 0.45 – 0.5 | 0.47 |
| Mn | 0.7 – 0.9 | 0.8 |
| Sifor fine-grain killed steel | 0.15 – 0.35 | 0.25 |
| Mohardenability + temper-embrittlement resistance | 0.2 – 0.3 | 0.25 |
| P | ≤ 0.04 | |
| Smax (H-grades / resulfurized variants differ) | ≤ 0.04 | |
| Fe | balance |
What surface finishes work on 4047?
No corrosion resistance of its own: use black oxide, phosphate + oil, zinc/zinc-nickel plating (bake at 190–200 °C within 4 h if above ~1000 MPa) or paint; hardened surfaces polish and hard-chrome plate well.
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 4047 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- G40470
How much does 4047 cost?
4047 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.
4047 — frequently asked
What is 4047 used for?
4047 is typically used for high-strength bolts, springs and fasteners. In short: highest-carbon 40xx grade; fastener-oriented alloy steel; difficult to weld.
What is the yield strength of 4047?
4047 has a typical yield strength of 400 MPa (58 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 60% of steel grades. Strength varies by condition: see the 11 listed tempers.
Is 4047 easy to machine?
Reasonably — machinability is rated good (55/100, better than 62% of steel grades). Machine in the annealed or ≤32 HRC condition with carbide tooling and rigid setups; above 40 HRC switch to CBN/ceramic or grind, and expect roughly half the tool life of 1045.
Can 4047 be welded?
Not readily — weldability is rated poor (28/100). Difficult — CE ≈ 0.65–0.70; preheat 300–400 °C, use low-hydrogen consumables, keep interpass temperature and temper immediately after welding to avoid hydrogen and quench cracking.
What surface finishes work on 4047?
No corrosion resistance of its own: use black oxide, phosphate + oil, zinc/zinc-nickel plating (bake at 190–200 °C within 4 h if above ~1000 MPa) or paint; hardened surfaces polish and hard-chrome plate well.
Can 4047 be formed, bent or molded?
Cold form only in the spheroidize-annealed condition (upsetting of fastener blanks); otherwise hot forge at 1050–1200 °C and normalize afterwards.
What is the maximum service temperature of 4047?
4047 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 4047-A and 4047-QT205?
A is the default condition — choose for rough machining, cold sawing and stock that will be heat treated after fabrication. QT205: maximum hardness/wear condition for small sections; very low toughness, avoid where impact or notches exist. Yield strength is 400 MPa in A versus 1,450 MPa in QT205.
How much does 4047 cost?
4047 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)
- ASTM A29/A29M — General Requirements for Steel Bars, Carbon and Alloy, Hot-Wrought — ASTM International (2020)
- SAE J1268 — Hardenability Bands for Carbon and Alloy H Steels — SAE International (2019)
- 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; 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.