Steel En47-SA (Spheroidize annealed)
Heat-treated state
Softest condition, used for cold heading, deep drawing or heavy cold forming of blanks.
Values for the SA condition
Other En47 tempers and conditions
En47 is listed in 10 conditions; see the grade overview at En47.
Compare all 10 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
SAThis page Spheroidize annealed | Softest condition, used for cold heading, deep drawing or heavy cold forming of blanks. | 400 | 660 | 25 | 11 HRC | 8.5 % IACS |
Solution annealed | Pick for machining, cold bending or blanking of spring blanks before hardening. | 450 | 750 | 20 | 225 HB | — |
Hot rolled | Cheapest mill condition for stock that will be forged or fully heat treated afterwards. | 600 | 950 | 14 | 29 HRC | — |
Normalized | Uniform fine-grain structure after forging; a good base condition before hardening. | 650 | 1,000 | 15 | 31 HRC | — |
Cold drawn | Close tolerance bright bar for machined parts that will be hardened later. | 700 | 860 | 10 | 24 HRC | 7.8 % IACS |
Q&T 28–32 HRC | Tough machinable condition for shafts, tools and lightly loaded torsion members. | 880 | 1,000 | 15 | 30 HRC | — |
Q&T 36–40 HRC | Balanced strength/toughness for torsion bars and medium-duty springs. | 1,120 | 1,250 | 12 | 38 HRC | — |
Q&T 40–44 HRC | Common leaf-spring and heavy coil-spring hardness with useful residual toughness. | 1,270 | 1,400 | 10 | 42 HRC | — |
QT44-48Default Q&T 44–48 HRC | Standard working hardness of En47 springs and torsion bars — best strength/relaxation compromise. | 1,450 | 1,600 | 8 | 46 HRC | — |
Q&T 48–52 HRC | Maximum spring load capacity, chisels and punches; toughness and notch tolerance drop sharply. | 1,620 | 1,800 | 6 | 50 HRC | — |
What is En47-SA?
En47-SA is En47 heat treated to SA — softest condition, used for cold heading, deep drawing or heavy cold forming of blanks. En47-SA has a yield strength of 400 MPa (58 ksi) and a tensile strength of 660 MPa (95.7 ksi) — weaker than 60% of steel grades. Elongation at break is 25% and the elastic modulus is 207 GPa (30 Msi). En47-SA 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). QT44-48 is the default condition FabDigit quotes; SA is available on request or by drawing note.
Advantages
- Easy to machine — 62/100, better than 89% of steel grades
- Polishes to a fine finish — 65/100, better than 78% of steel grades
- Ductile — tolerates forming and impact — 25%, better than 77% of steel grades
Limitations
- Limited service temperature — 300°C (572 °F), worse than 78% of steel grades
En47-SA properties
Typical room-temperature values for En47-SA; 23 are specific to this condition. Other listed values are En47 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
En47-SA 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
En47-SA has a yield strength of 400 MPa (58 ksi) and a tensile strength of 660 MPa (95.7 ksi) — weaker than 60% of steel grades. Elongation at break is 25% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
En47-SA is rated for continuous service to 300°C (572 °F). It conducts heat at 46 W/m·K (26.6 BTU/hr·ft·°F), better than 71% of steel grades. Thermal expansion is 12.2 µm/m·K (6.78 µin/in·°F).
Electrical3
En47-SA conducts electricity at 8.5 % IACS, better than 63% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of En47-SA takes about 27 MJ of energy and emits 2.3 kg of CO₂ — less than 59% of steel grades. Typical recycled content is 30%.
Manufacturability7
En47-SA's machinability is good (62/100, better than 89% of steel grades); weldability fair (35/100); formability good (55/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with En47-SA
Is En47 easy to machine?
Machine in the annealed/spheroidized state (~60 % of 1212); above 40 HRC use carbide or CBN with rigid setups, or finish by grinding.
Can En47 be welded?
Poor weldability (CE ≈ 0.9): preheat 250–350 °C, low-hydrogen consumables, immediate post-weld temper — avoid welding on finished springs.
Can En47 be formed, bent or molded?
Cold form or coil only when annealed or as pre-tempered spring strip/wire; hot form at 950–1100 °C, then harden 830–860 °C oil quench and temper 380–520 °C to the target hardness.
What surface finishes work on En47?
No corrosion resistance bare — shot peen then phosphate + oil, powder coat or zinc plate with 190–220 °C bake to avoid hydrogen embrittlement; decarburised skin must be ground off before service.
En47 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 | 0.45 – 0.55 | 0.5 |
| Si | 0.1 – 0.35 | 0.25 |
| Mn | 0.5 – 0.8 | 0.65 |
| Cr | 0.9 – 1.2 | 1.05 |
| V0.15 % minimum in BS 970 En47; EN 10089 50CrV4 specifies 0.10–0.25 % | 0.15 – 0.25 | 0.18 |
| P | ≤ 0.04 | — |
| Smax (0.025 max for spring quality) | ≤ 0.04 | — |
| Fe | balance | — |
En47-SA — frequently asked
What is En47-SA used for?
En47-SA is typically used for coil springs, torsion bars and valve springs. In short: high-duty Cr-V spring steel; 50CrV4 / 6150 equivalent; hardest grade in family.
What is the yield strength of En47-SA?
En47-SA has a typical yield strength of 400 MPa (58 ksi) and a tensile strength of 660 MPa (95.7 ksi) — weaker than 60% of steel grades. Strength varies by condition: see the 10 listed tempers.
Is En47-SA easy to machine?
Reasonably — machinability is rated good (62/100, better than 89% of steel grades). Machine in the annealed/spheroidized state (~60 % of 1212); above 40 HRC use carbide or CBN with rigid setups, or finish by grinding.
Can En47-SA be welded?
With care — weldability is rated fair (35/100). Poor weldability (CE ≈ 0.9): preheat 250–350 °C, low-hydrogen consumables, immediate post-weld temper — avoid welding on finished springs.
What surface finishes work on En47-SA?
No corrosion resistance bare — shot peen then phosphate + oil, powder coat or zinc plate with 190–220 °C bake to avoid hydrogen embrittlement; decarburised skin must be ground off before service.
Can En47-SA be formed, bent or molded?
Cold form or coil only when annealed or as pre-tempered spring strip/wire; hot form at 950–1100 °C, then harden 830–860 °C oil quench and temper 380–520 °C to the target hardness.
What is the maximum service temperature of En47-SA?
En47-SA 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 En47 QT44-48 and En47-SA?
QT44-48 is the default condition — standard working hardness of En47 springs and torsion bars — best strength/relaxation compromise. SA: softest condition, used for cold heading, deep drawing or heavy cold forming of blanks. Yield strength is 1,450 MPa in QT44-48 versus 400 MPa in SA.
Sources
- BS 970-1: Wrought steels for mechanical and allied engineering purposes (En47 / 735A50) — BSI (1991)
- EN 10089: Hot-rolled steels for quenched and tempered springs (50CrV4, 1.8159) — CEN (2002)
- EN 10270-2: Steel wire for mechanical springs — oil hardened and tempered wire — CEN (2011)
- ASTM A689 / SAE J404 (AISI 6150 alloy spring steel) — ASTM / SAE (2015)
- GB/T 1222 (50CrVA) — SAC (2016)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.19 — Fatigue and Fracture (spring steels) — ASM International (1996)
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.