Precious Metal B541-SR (Stress relieved)
Heat-treated state
GB B541
Use for formed springs and wipers needing dimensional stability and higher elastic limit without full age hardening.
Values for the SR condition
Other B541 tempers and conditions
B541 is listed in 5 conditions; see the grade overview at B541.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Choose for deep drawing, heading of contact rivets and any severe cold forming before final age hardening. | 200 | 430 | 30 | 120 HV | 8.5 % IACS |
SRThis page Stress relieved | Use for formed springs and wipers needing dimensional stability and higher elastic limit without full age hardening. | 560 | 700 | 5 | 205 HV | 8.5 % IACS |
Age hardened from the annealed condition | Pick when parts must be formed soft, then hardened in place — good hardness with usable ductility and low distortion. | 620 | 800 | 8 | 235 HV | 9.5 % IACS |
Cold worked | Drawn or rolled to temper for spring contacts where a subsequent aging bake is not wanted. | 640 | 760 | 3 | 215 HV | 8 % IACS |
HT-CWDefault Age hardened from the cold worked condition | Highest strength, hardness and wear life — standard condition for finished contact wire, rivets, brushes and slip-ring fingers. | 850 | 1,000 | 2 | 280 HV | 10 % IACS |
What is B541-SR?
B541-SR is B541 heat treated to SR — use for formed springs and wipers needing dimensional stability and higher elastic limit without full age hardening. B541-SR has a yield strength of 560 MPa (81.2 ksi) and a tensile strength of 700 MPa (102 ksi) — stronger than 97% of precious metal grades. Elongation at break is 5% and the elastic modulus is 102 GPa (14.8 Msi). B541-SR has a density of 16 g/cm³ (0.578 lb/in³), heavier than 84% of precious metal grades. It melts at 1,000°C (1,832 °F). HT-CW is the default condition FabDigit quotes; SR is available on request or by drawing note.
Advantages
- High strength — 560 MPa (81.2 ksi), better than 97% of precious metal grades
- Good corrosion resistance — 98/100, better than 90% of precious metal grades
- Polishes to a fine finish — 95/100, better than 86% of precious metal grades
Limitations
- Limited ductility — 5%, worse than 93% of precious metal grades
- Limited formability — 35/100, worse than 92% of precious metal grades
- Low electrical conductivity — 8.5 % IACS, worse than 85% of precious metal grades
- Heavy — 16 g/cm³ (0.578 lb/in³), worse than 84% of precious metal grades
- High embodied carbon — 13,000 kg CO₂/kg, worse than 81% of precious metal grades
B541-SR properties
Typical room-temperature values for B541-SR; 12 are specific to this condition. Other listed values are B541 reference data and may not represent this condition. Bars are the position among precious metal grades.
Physical3
B541-SR has a density of 16 g/cm³ (0.578 lb/in³), heavier than 84% of precious metal grades. It melts at 1,000°C (1,832 °F).
Mechanical10
B541-SR has a yield strength of 560 MPa (81.2 ksi) and a tensile strength of 700 MPa (102 ksi) — stronger than 97% of precious metal grades. Elongation at break is 5% and the elastic modulus is 102 GPa (14.8 Msi).
Thermal6
B541-SR is rated for continuous service to 230°C (446 °F). It conducts heat at 55 W/m·K (31.8 BTU/hr·ft·°F), worse than 76% of precious metal grades. Thermal expansion is 15 µm/m·K (8.33 µin/in·°F).
Electrical3
B541-SR conducts electricity at 8.5 % IACS, worse than 85% of precious metal grades.
Chemical & Environmental3
Corrosion resistance is excellent (98/100), better than 90% of precious metal grades.
Sustainability4
Producing a kilogram of B541-SR takes about 170,000 MJ of energy and emits 13,000 kg of CO₂ — more than 74% of precious metal grades. Typical recycled content is 60%.
Manufacturability8
B541-SR's machinability is fair (38/100, worse than 66% of precious metal grades); weldability very good (70/100); formability fair (35/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with B541-SR
Is B541 easy to machine?
Machine in the aged condition with sharp, high-rake carbide or diamond tools, light cuts and full swarf recovery — all chips and coolant are refined for precious-metal value.
Can B541 be welded?
Contacts are attached by resistance or laser welding, or by brazing to Cu/CuNi carriers; fusion welding of the alloy itself is rarely done and can dissolve the age-hardening structure.
Can B541 be formed, bent or molded?
Form, draw, head and coin in the annealed condition with interstage anneals, then age harden to final properties; aged material has very little remaining ductility.
What surface finishes work on B541?
Not anodizable; surfaces are diamond-turned, burnished or lightly polished, and can be hard-gold electroplated locally — avoid mercury, halogen and sulfur-bearing compounds.
B541 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 |
|---|---|---|
| Augold content is the specified base; verify exact limits against the current ASTM B541 table | 68 – 70 | 69 |
| Ag | 24 – 26 | 25 |
| Ptprovides age-hardening response with Au-Ag | 5 – 7 | 6 |
| Other (total impurities)Cu, Ni, Zn, Fe and other trace elements | ≤ 0.15 | — |
B541-SR — frequently asked
What is B541-SR used for?
B541-SR is typically used for connector contacts, low-level signal switches and precision relays. In short: age-hardened gold contact; highest strength in group; very limited ductility when aged.
What is the yield strength of B541-SR?
B541-SR has a typical yield strength of 560 MPa (81.2 ksi) and a tensile strength of 700 MPa (102 ksi) — stronger than 97% of precious metal grades. Strength varies by condition: see the 5 listed tempers.
Is B541-SR easy to machine?
Not especially — machinability is rated fair (38/100, worse than 66% of precious metal grades). Machine in the aged condition with sharp, high-rake carbide or diamond tools, light cuts and full swarf recovery — all chips and coolant are refined for precious-metal value.
Can B541-SR be welded?
Yes — weldability is rated very good (70/100). Contacts are attached by resistance or laser welding, or by brazing to Cu/CuNi carriers; fusion welding of the alloy itself is rarely done and can dissolve the age-hardening structure.
What surface finishes work on B541-SR?
Not anodizable; surfaces are diamond-turned, burnished or lightly polished, and can be hard-gold electroplated locally — avoid mercury, halogen and sulfur-bearing compounds.
Can B541-SR be formed, bent or molded?
Form, draw, head and coin in the annealed condition with interstage anneals, then age harden to final properties; aged material has very little remaining ductility.
What is the maximum service temperature of B541-SR?
B541-SR is rated for continuous use to about 230°C (446 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between B541 HT-CW and B541-A?
HT-CW is the default condition — highest strength, hardness and wear life — standard condition for finished contact wire, rivets, brushes and slip-ring fingers. A: choose for deep drawing, heading of contact rivets and any severe cold forming before final age hardening. Yield strength is 850 MPa in HT-CW versus 200 MPa in A.
Sources
- ASTM B541 Standard Specification for Gold Electrical Contact Alloy — ASTM International (2018)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials (precious metals and electrical contact materials) — ASM International (1990)
- Precious-metal electrical contact alloy datasheets (Au-Ag-Pt age-hardenable grades) — Deringer-Ney / Materion (2023)
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.