Precious Metal S990
S990 is a fine-silver jewelry grade of minimum 99.0% Ag, defined under hallmarking standards for traditional 'thousand-fine' silver work.
Reference datasheet — S990 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 O condition
S990 tempers and conditions
S990 is supplied in 5 conditions, soft to hard. O is the default FabDigit quotes; the values on this page are for it.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
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?
S990 is a fine-silver jewelry grade of minimum 99.0% Ag, defined under hallmarking standards for traditional 'thousand-fine' silver work. It is selected where colour, fineness and workability outrank strength: 45% elongation, formability score 98, 97% IACS electrical conductivity and 405 W/m·K thermal conductivity, supplied as sheet, wire, grain and castings in O, H01, H02, H04 and F conditions. Yield is only 50 MPa with 150 MPa tensile and 30 HB, so thin sections dent and deform in handling, and the surface blackens in sulfur-bearing air up to its 400 °C service limit. S925 sterling is the practical alternative when wear resistance or spring temper is required. S990 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). S990 has a yield strength of 50 MPa (7.25 ksi) and a tensile strength of 150 MPa (21.8 ksi) — weaker than 97% of precious metal grades. Elongation at break is 45% and the elastic modulus is 78 GPa (11.3 Msi).
What is S990 used for?
- jewelry
- ornamental silverware
- gift items
Advantages
- Ductile — tolerates forming and impact — 45%, better than 97% of precious metal grades
- Conducts heat well — 405 W/m·K (234 BTU/hr·ft·°F), better than 97% of precious metal grades
- High electrical conductivity — 97 % IACS, better than 97% of precious metal grades
- Forms and bends easily — 98/100, better than 97% of precious metal grades
- Polishes to a fine finish — 96/100, better than 94% of precious metal grades
Limitations
- Low strength — 50 MPa (7.25 ksi), worse than 97% of precious metal grades
- Low stiffness — 78 GPa (11.3 Msi), worse than 90% of precious metal grades
S990 properties
Typical room-temperature values for S990-O; bars are the position among precious metal grades.
Physical3
S990 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 has a yield strength of 50 MPa (7.25 ksi) and a tensile strength of 150 MPa (21.8 ksi) — weaker than 97% of precious metal grades. Elongation at break is 45% and the elastic modulus is 78 GPa (11.3 Msi).
Thermal6
S990 is rated for continuous service to 400°C (752 °F). It conducts heat at 405 W/m·K (234 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 conducts electricity at 97 % IACS, better than 97% of precious metal grades.
Chemical & Environmental3
Corrosion resistance is very good (80/100), worse than 52% of precious metal grades.
Sustainability4
Producing a kilogram of S990 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's machinability is fair (50/100, better than 74% of precious metal grades); weldability good (60/100); formability excellent (98/100).
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 precious metal family
Yield strength against density for every precious metal grade FabDigit runs. S990 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with S990
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.
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) |
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.
How much does S990 cost?
S990 is a high-cost precious metal ($$$$), pricier than about 78% 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.
S990 — frequently asked
What is S990 used for?
S990 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?
S990 has a typical yield strength of 50 MPa (7.25 ksi) and a tensile strength of 150 MPa (21.8 ksi) — weaker than 97% of precious metal grades. Strength varies by condition: see the 5 listed tempers.
Is S990 easy to machine?
Reasonably — machinability is rated fair (50/100, better than 74% 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 be welded?
Yes — weldability is rated good (60/100). 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?
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 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?
S990 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.
How much does S990 cost?
S990 is a high-cost precious metal ($$$$), pricier than about 78% 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
- 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; 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.