Steel 4063-N (Normalized)
Heat-treated state
AISI/SAE 4063 · UNS G40630
Use to homogenize forgings and refine grain before hardening; not a service condition for springs.
Values for the N condition
Other 4063 tempers and conditions
4063 is listed in 9 conditions; see the grade overview at 4063.
Compare all 9 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Choose for cold coiling, machining or blanking before final quench-and-temper. | 420 | 730 | 22 | 210 HB | — |
Hot rolled | Mill supply condition for forging or hot coiling followed by heat treatment. | 540 | 950 | 14 | 28 HRC | 8.2 % IACS |
NThis page Normalized | Use to homogenize forgings and refine grain before hardening; not a service condition for springs. | 700 | 1,100 | 13 | 34 HRC | 8 % IACS |
Cold drawn | Pick for close tolerance bar or hard-drawn spring wire where no further hardening is planned. | 860 | 1,030 | 9 | 31 HRC | 8 % IACS |
Q&T | Softest quench-and-temper level: best toughness and machinability, lowest set resistance. | 910 | 1,060 | 19 | 31 HRC | — |
Q&T | Tougher, more machinable condition for large sections and shock-loaded spring or link parts. | 1,160 | 1,350 | 15 | 42 HRC | — |
OQT425Default Q&T | Standard service condition for heavy coil and leaf springs — best balance of strength, set resistance and fatigue life. | 1,365 | 1,660 | 12 | 48 HRC | — |
Q&T | High-strength spring and fastener condition where a little more ductility than 205 °C temper is needed. | 1,655 | 2,000 | 10 | 53 HRC | — |
Q&T | Maximum strength and wear resistance; very low toughness, use only for low-impact, high-stress parts. | 1,790 | 2,380 | 10 | 58 HRC | — |
What is 4063-N?
4063-N is 4063 heat treated to N — use to homogenize forgings and refine grain before hardening; not a service condition for springs. 4063-N has a yield strength of 700 MPa (102 ksi) and a tensile strength of 1,100 MPa (160 ksi) — stronger than 81% of steel grades. Elongation at break is 13% and the elastic modulus is 205 GPa (29.7 Msi). 4063-N has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,400°C (2,552 °F). OQT425 is the default condition FabDigit quotes; N is available on request or by drawing note.
Advantages
- High strength — 700 MPa (102 ksi), better than 81% of steel grades
- Polishes to a fine finish — 65/100, better than 78% of steel grades
Limitations
- Difficult to weld — 18/100, worse than 87% of steel grades
- Low fracture toughness — 55 MPa·√m (50.1 ksi·√in), worse than 82% of steel grades
- Limited ductility — 13%, worse than 78% of steel grades
- Difficult to machine — 40/100, worse than 77% of steel grades
4063-N properties
Typical room-temperature values for 4063-N; 22 are specific to this condition. Other listed values are 4063 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
4063-N has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,400°C (2,552 °F).
Mechanical15
4063-N has a yield strength of 700 MPa (102 ksi) and a tensile strength of 1,100 MPa (160 ksi) — stronger than 81% of steel grades. Elongation at break is 13% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
4063-N 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 11.5 µm/m·K (6.39 µin/in·°F).
Electrical3
4063-N conducts electricity at 8 % IACS, better than 55% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 86% of steel grades.
Sustainability4
Producing a kilogram of 4063-N takes about 31 MJ of energy and emits 2.3 kg of CO₂ — more than 64% of steel grades. Typical recycled content is 30%.
Manufacturability6
4063-N's machinability is fair (40/100, worse than 77% of steel grades); weldability poor (18/100); formability poor (25/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 4063-N
Is 4063 easy to machine?
Machine in the annealed or ≤33 HRC tempered state with carbide tooling, rigid setups and generous coolant; grinding is the practical route above 45 HRC.
Can 4063 be welded?
Not recommended as a welded grade — 0.63 %C gives high crack sensitivity; if unavoidable, preheat 250–350 °C, use low-hydrogen consumables and post-weld temper immediately.
Can 4063 be formed, bent or molded?
Cold coil or bend only in the spheroidize-annealed condition with generous radii; otherwise hot form at 900–1050 °C, then austenitize ~815–845 °C, oil quench and temper.
What surface finishes work on 4063?
Shot peen springs for fatigue life, then phosphate + oil, powder coat or zinc-rich paint; avoid unbaked electroplating (hydrogen embrittlement) at high hardness.
4063 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 grade of the SAE 40xx series | 0.6 – 0.67 | 0.63 |
| Mn | 0.75 – 1 | 0.88 |
| Si | 0.15 – 0.35 | 0.25 |
| Mohardenability and temper resistance | 0.2 – 0.3 | 0.25 |
| P | ≤ 0.04 | — |
| S | ≤ 0.04 | — |
| Fe | balance | — |
4063-N — frequently asked
What is 4063-N used for?
4063-N is typically used for coil springs, leaf springs and torsion bars. In short: high-strength spring steel; 48 HRC after oil quench; not a welding grade.
What is the yield strength of 4063-N?
4063-N has a typical yield strength of 700 MPa (102 ksi) and a tensile strength of 1,100 MPa (160 ksi) — stronger than 81% of steel grades. Strength varies by condition: see the 9 listed tempers.
Is 4063-N easy to machine?
Not especially — machinability is rated fair (40/100, worse than 77% of steel grades). Machine in the annealed or ≤33 HRC tempered state with carbide tooling, rigid setups and generous coolant; grinding is the practical route above 45 HRC.
Can 4063-N be welded?
Not readily — weldability is rated poor (18/100). Not recommended as a welded grade — 0.63 %C gives high crack sensitivity; if unavoidable, preheat 250–350 °C, use low-hydrogen consumables and post-weld temper immediately.
What surface finishes work on 4063-N?
Shot peen springs for fatigue life, then phosphate + oil, powder coat or zinc-rich paint; avoid unbaked electroplating (hydrogen embrittlement) at high hardness.
Can 4063-N be formed, bent or molded?
Cold coil or bend only in the spheroidize-annealed condition with generous radii; otherwise hot form at 900–1050 °C, then austenitize ~815–845 °C, oil quench and temper.
What is the maximum service temperature of 4063-N?
4063-N 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 4063 OQT425 and 4063-A?
OQT425 is the default condition — standard service condition for heavy coil and leaf springs — best balance of strength, set resistance and fatigue life. A: choose for cold coiling, machining or blanking before final quench-and-temper. Yield strength is 1,365 MPa in OQT425 versus 420 MPa in A.
Sources
- SAE J404 — Chemical Compositions of SAE Alloy Steels — SAE International (2021)
- SAE J1268 — Hardenability Bands for Alloy H-Steels — SAE International (2019)
- ASTM A29/A29M — General Requirements for Steel Bars, Carbon and Alloy, Hot-Wrought — ASTM (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)
- SAE HS-788 / Spring Design Manual — SAE International (1996)
- MatWeb alloy steel data sheets (SAE 40xx series) — MatWeb LLC (2024)
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.