Precious Metal S990-F (As fabricated)
Temper
Investment-cast jewelry, teaware bodies and figurines before finishing; coarse grain, lowest strength.
Values for the F condition
Other S990 tempers and conditions
S990 is listed in 5 conditions; see the grade overview at S990.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
FThis page As fabricated | Investment-cast jewelry, teaware bodies and figurines before finishing; coarse grain, lowest strength. | 45 | 140 | 25 | 28 HB | 95 % IACS |
ODefault Annealed | Standard supply condition for sheet, wire and tube that will be hammered, drawn, chased or filigree-worked. | 50 | 150 | 45 | 30 HB | 97 % IACS |
Quarter hard | Light cold work for sheet that must hold shape during stamping yet still bend without cracking. | 150 | 200 | 20 | 52 HB | 96 % IACS |
Half hard | Half-hard strip and wire for bangle stock, chain links and settings needing spring-back resistance. | 200 | 240 | 10 | 66 HB | 95 % IACS |
Full hard | Hard-drawn wire and rolled strip where maximum stiffness and scratch resistance matter (clasps, pins, chain). | 250 | 290 | 4 | 82 HB | 94 % IACS |
What is S990-F?
S990-F is S990 in the F temper — investment-cast jewelry, teaware bodies and figurines before finishing; coarse grain, lowest strength. S990-F has a yield strength of 45 MPa (6.53 ksi) and a tensile strength of 140 MPa (20.3 ksi) — weaker than 98% of precious metal grades. Elongation at break is 25% and the elastic modulus is 76 GPa (11 Msi). S990-F has a density of 10.48 g/cm³ (0.379 lb/in³), heavier than 54% of precious metal grades. It melts at 940°C (1,724 °F). O is the default condition FabDigit quotes; F is available on request or by drawing note.
Advantages
- Conducts heat well — 398 W/m·K (230 BTU/hr·ft·°F), better than 97% of precious metal grades
- High electrical conductivity — 95 % IACS, better than 97% of precious metal grades
- Polishes to a fine finish — 96/100, better than 94% of precious metal grades
Limitations
- Low strength — 45 MPa (6.53 ksi), worse than 98% of precious metal grades
- Low stiffness — 76 GPa (11 Msi), worse than 96% of precious metal grades
S990-F properties
Typical room-temperature values for S990-F; 18 are specific to this condition. Other listed values are S990 reference data and may not represent this condition. Bars are the position among precious metal grades.
Physical3
S990-F has a density of 10.48 g/cm³ (0.379 lb/in³), heavier than 54% of precious metal grades. It melts at 940°C (1,724 °F).
Mechanical12
S990-F has a yield strength of 45 MPa (6.53 ksi) and a tensile strength of 140 MPa (20.3 ksi) — weaker than 98% of precious metal grades. Elongation at break is 25% and the elastic modulus is 76 GPa (11 Msi).
Thermal6
S990-F is rated for continuous service to 400°C (752 °F). It conducts heat at 398 W/m·K (230 BTU/hr·ft·°F), better than 97% of precious metal grades. Thermal expansion is 19.6 µm/m·K (10.9 µin/in·°F).
Electrical3
S990-F conducts electricity at 95 % IACS, better than 97% of precious metal grades.
Chemical & Environmental3
Corrosion resistance is very good (78/100), worse than 56% of precious metal grades.
Sustainability4
Producing a kilogram of S990-F takes about 1,500 MJ of energy and emits 110 kg of CO₂ — more than 51% of precious metal grades. Typical recycled content is 30%.
Manufacturability8
S990-F's machinability is fair (48/100, better than 71% of precious metal grades); weldability good (55/100); formability excellent (85/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with S990-F
Is S990 easy to machine?
Very soft and gummy — use polished, high-rake carbide or HSS tools, high speed, light feed and generous lubricant to avoid smearing; collect all swarf for refining.
Can S990 be welded?
Best joined with laser/PUK spot welding or silver brazing alloys (Ag-Cu-Zn, 650–800 °C); its huge thermal conductivity demands high-power, short-duration heat input.
Can S990 be formed, bent or molded?
Outstanding cold formability — deep draws, raises and forges with 50–70 % reduction between anneals; anneal at 550–650 °C and quench/pickle to remove fire stain, and de-gas melts before investment casting.
What surface finishes work on S990?
Polishes to a mirror with tripoli/rouge; protect with rhodium plating, anti-tarnish lacquer or sulfur-absorbing storage since H₂S blackening is the main service issue.
S990 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 |
|---|---|---|
| Cuusual hardening/deoxidizing addition making up the remainder | ≤ 1 | 0.8 |
| Znoptional, used by some mills as deoxidizer in place of part of the Cu | ≤ 0.3 | 0.1 |
| Geoptional anti-tarnish micro-addition in some proprietary 990 alloys | ≤ 0.3 | — |
| Cdrestricted by GB 28480 jewelry harmful-element limits | ≤ 0.01 | — |
| Pbimpurity limit, refinery practice per ASTM B413 analogue | ≤ 0.02 | — |
| AgGB/T 11887 minimum fineness 990; hallmark S990 | ≥ 99 (balance) | — |
S990-F — frequently asked
What is S990-F used for?
S990-F is typically used for jewelry, ornamental silverware and gift items. In short: highest formability in family; near-pure jewelry fineness; softer than sterling.
What is the yield strength of S990-F?
S990-F has a typical yield strength of 45 MPa (6.53 ksi) and a tensile strength of 140 MPa (20.3 ksi) — weaker than 98% of precious metal grades. Strength varies by condition: see the 5 listed tempers.
Is S990-F easy to machine?
Reasonably — machinability is rated fair (48/100, better than 71% of precious metal grades). Very soft and gummy — use polished, high-rake carbide or HSS tools, high speed, light feed and generous lubricant to avoid smearing; collect all swarf for refining.
Can S990-F be welded?
Yes — weldability is rated good (55/100). Best joined with laser/PUK spot welding or silver brazing alloys (Ag-Cu-Zn, 650–800 °C); its huge thermal conductivity demands high-power, short-duration heat input.
What surface finishes work on S990-F?
Polishes to a mirror with tripoli/rouge; protect with rhodium plating, anti-tarnish lacquer or sulfur-absorbing storage since H₂S blackening is the main service issue.
Can S990-F be formed, bent or molded?
Outstanding cold formability — deep draws, raises and forges with 50–70 % reduction between anneals; anneal at 550–650 °C and quench/pickle to remove fire stain, and de-gas melts before investment casting.
What is the maximum service temperature of S990-F?
S990-F 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 S990-O and S990-H04?
O is the default condition — standard supply condition for sheet, wire and tube that will be hammered, drawn, chased or filigree-worked. H04: hard-drawn wire and rolled strip where maximum stiffness and scratch resistance matter (clasps, pins, chain). Yield strength is 50 MPa in O versus 250 MPa in H04.
Sources
- ASTM B413 Standard Specification for Refined Silver — ASTM International (2019)
- ASM Handbook Vol.2 — Properties and Selection: Nonferrous Alloys (Silver and Silver Alloys) — ASM International (1990)
- ASM Specialty Handbook / Handbook Vol.13B — Corrosion of Silver and Silver Alloys — ASM International (2005)
- CRC Handbook of Chemistry and Physics — thermophysical data for silver — CRC Press (2020)
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.