Steel 3J53 ST+A
Precip hard
GB 3J53 · also Elinvar
ST+A = solution treated and precipitation aged
Use for machined resonators, diaphragms and load cells needing near-zero modulus drift with good strength but no cold-work distortion.
Values for the ST+A condition
Other 3J53 tempers and conditions
3J53 is listed in 5 conditions; see the grade overview at 3J53.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
STDefault Solution annealed | Pick for stamping, coiling or machining of blanks before ageing to final elastic properties. | 330 | 760 | 35 | 172 HB | 2.2 % IACS |
Hot rolled | Mill feedstock for further forging, machining and heat treatment; not a functional elastic condition. | 400 | 800 | 28 | 15 HRC | 2.2 % IACS |
ST+AThis page Solution treated and precipitation aged | Use for machined resonators, diaphragms and load cells needing near-zero modulus drift with good strength but no cold-work distortion. | 830 | 1,180 | 15 | 36 HRC | — |
Cold worked | Intermediate condition supplied for spring winding or forming immediately before customer ageing; cold-work level sets the final thermoelastic coefficient. | 1,000 | 1,150 | 5 | 34 HRC | 2.1 % IACS |
Cold worked then aged | Standard final condition for precision springs, hairsprings and tuning-fork resonators where the thermoelastic coefficient is trimmed to ~0. | 1,300 | 1,500 | 5 | 45 HRC | — |
What is 3J53 ST+A?
3J53 ST+A is 3J53 in the ST+A condition — use for machined resonators, diaphragms and load cells needing near-zero modulus drift with good strength but no cold-work distortion. 3J53 ST+A has a yield strength of 830 MPa (120 ksi) and a tensile strength of 1,180 MPa (171 ksi) — stronger than 87% of steel grades. Elongation at break is 15% and the elastic modulus is 170 GPa (24.7 Msi). 3J53 ST+A has a density of 8.14 g/cm³ (0.294 lb/in³), heavier than 97% of steel grades. It melts at 1,425°C (2,597 °F). ST is the default condition FabDigit quotes; ST+A is available on request or by drawing note.
Advantages
- Good corrosion resistance — 40/100, better than 98% of steel grades
- High strength — 830 MPa (120 ksi), better than 87% of steel grades
- Polishes to a fine finish — 65/100, better than 78% of steel grades
Limitations
- High embodied carbon — 9 kg CO₂/kg, worse than 100% of steel grades
- Poor heat conductor — 12.6 W/m·K (7.28 BTU/hr·ft·°F), worse than 99% of steel grades
- Low electrical conductivity — 2.2 % IACS, worse than 98% of steel grades
- Low stiffness — 170 GPa (24.7 Msi), worse than 97% of steel grades
- Difficult to machine — 22/100, worse than 95% of steel grades
3J53 ST+A properties
Typical room-temperature values for 3J53 ST+A; 10 are specific to this condition. Other listed values are 3J53 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
3J53 ST+A has a density of 8.14 g/cm³ (0.294 lb/in³), heavier than 97% of steel grades. It melts at 1,425°C (2,597 °F).
Mechanical15
3J53 ST+A has a yield strength of 830 MPa (120 ksi) and a tensile strength of 1,180 MPa (171 ksi) — stronger than 87% of steel grades. Elongation at break is 15% and the elastic modulus is 170 GPa (24.7 Msi).
Thermal5
3J53 ST+A is rated for continuous service to 200°C (392 °F). It conducts heat at 12.6 W/m·K (7.28 BTU/hr·ft·°F), worse than 99% of steel grades. Thermal expansion is 7.9 µm/m·K (4.39 µin/in·°F).
Electrical3
3J53 ST+A conducts electricity at 2.2 % IACS, worse than 98% of steel grades.
Chemical & Environmental3
Corrosion resistance is fair (40/100), better than 98% of steel grades.
Sustainability4
Producing a kilogram of 3J53 ST+A takes about 130 MJ of energy and emits 9 kg of CO₂ — more than 100% of steel grades. Typical recycled content is 20%.
Manufacturability7
3J53 ST+A's machinability is poor (22/100, worse than 95% of steel grades); weldability fair (50/100); formability poor (25/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 3J53 ST+A
Is 3J53 easy to machine?
Machine in the solution-treated state with sharp carbide tools, low speed (≈15–25 m/min), heavy positive rake and flood coolant; the alloy work-hardens and galls like Invar, so finish-machine before ageing where possible.
Can 3J53 be welded?
TIG/plasma/electron-beam and resistance welding are used with matching or Ni-base filler under good shielding; Ti and Al oxidize readily, and joints must be re-solution-treated and aged to restore the constant-modulus behaviour.
Can 3J53 be formed, bent or molded?
Stamp, coil and deep-draw in the soft solution-treated condition; cold-reduction percentage before ageing is the key process variable that trims the thermoelastic coefficient to zero.
What surface finishes work on 3J53?
Not stainless — passivate, electropolish or Ni/Cr/Au plate, or protect with oil; can be lapped and mirror-polished for resonator surfaces, and mild oxide from ageing is removed by pickling or electropolishing.
3J53 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 |
|---|---|---|
| Nicontrols Curie point and thermoelastic coefficient | 41 – 43.5 | 42 |
| Cr | 5 – 6 | 5.5 |
| Tiγ' precipitation hardener | 2.2 – 2.7 | 2.4 |
| Al | 0.3 – 0.8 | 0.55 |
| Mn | ≤ 0.8 | 0.4 |
| Si | ≤ 0.5 | 0.3 |
| C | ≤ 0.05 | 0.03 |
| P | ≤ 0.02 | — |
| S | ≤ 0.02 | — |
| Fe | balance | — |
3J53 ST+A — frequently asked
What is 3J53 ST+A used for?
3J53 ST+A is typically used for watch/clock hairsprings, precision balance springs, tuning forks and frequency-critical mechanical resonators. In short: constant-modulus spring alloy; near-zero thermoelastic coefficient; invar-like machining behaviour.
What is the yield strength of 3J53 ST+A?
3J53 ST+A has a typical yield strength of 830 MPa (120 ksi) and a tensile strength of 1,180 MPa (171 ksi) — stronger than 87% of steel grades. Strength varies by condition: see the 5 listed tempers.
Is 3J53 ST+A easy to machine?
Not especially — machinability is rated poor (22/100, worse than 95% of steel grades). Machine in the solution-treated state with sharp carbide tools, low speed (≈15–25 m/min), heavy positive rake and flood coolant; the alloy work-hardens and galls like Invar, so finish-machine before ageing where possible.
Can 3J53 ST+A be welded?
With care — weldability is rated fair (50/100). TIG/plasma/electron-beam and resistance welding are used with matching or Ni-base filler under good shielding; Ti and Al oxidize readily, and joints must be re-solution-treated and aged to restore the constant-modulus behaviour.
What surface finishes work on 3J53 ST+A?
Not stainless — passivate, electropolish or Ni/Cr/Au plate, or protect with oil; can be lapped and mirror-polished for resonator surfaces, and mild oxide from ageing is removed by pickling or electropolishing.
Can 3J53 ST+A be formed, bent or molded?
Stamp, coil and deep-draw in the soft solution-treated condition; cold-reduction percentage before ageing is the key process variable that trims the thermoelastic coefficient to zero.
What is the maximum service temperature of 3J53 ST+A?
3J53 ST+A is rated for continuous use to about 200°C (392 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 3J53-ST and 3J53-CW?
ST is the default condition — pick for stamping, coiling or machining of blanks before ageing to final elastic properties. CW: intermediate condition supplied for spring winding or forming immediately before customer ageing; cold-work level sets the final thermoelastic coefficient. Yield strength is 330 MPa in ST versus 1,000 MPa in CW.
Sources
- Ni-Span-C alloy 902 datasheet (equivalent grade) — Special Metals Corporation (2004)
- ASM Handbook Vol. 2 — Properties of Fe-Ni Controlled-Expansion/Modulus Alloys — ASM International (1990)
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.