Copper Alloy QCr0.5-M
Heat-treated state
GB QCr0.5
M = thermomechanically controlled processed
Softest condition for deep forming, spinning or subsequent solution treatment; low strength and only moderate conductivity if Cr is partly in solution.
Values for the M condition
Other QCr0.5 tempers and conditions
QCr0.5 is listed in 8 conditions; see the grade overview at QCr0.5.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution heat treated | Supersaturated, soft and ductile — pick when the part must be formed or machined before precipitation ageing. | 90 | 235 | 42 | 50 HB | 42 % IACS |
MThis page Thermomechanically controlled processed | Softest condition for deep forming, spinning or subsequent solution treatment; low strength and only moderate conductivity if Cr is partly in solution. | 100 | 250 | 40 | 55 HB | 55 % IACS |
hot forged, solution treated and aged | Forged electrode caps, mould inserts and large blocks where TH tempers are impractical; properties near TF00 with some section-size scatter. | 290 | 400 | 22 | 115 HB | 80 % IACS |
TF00Default Solution heat treated and precipitation hardened | The standard stocked condition: best balance of ~420 MPa strength with >80 % IACS conductivity — the classic RWMA Class 2 resistance-welding electrode temper. | 315 | 420 | 22 | 125 HB | 82 % IACS |
Solution heat treated and cold worked, full hard | Cold-drawn hard bar/wire supplied for later ageing or for uses where conductivity is secondary to strength. | 345 | 400 | 12 | 110 HB | 45 % IACS |
TD01 and precipitation hardened | Slightly cold-worked and aged strip/rod when straightness and modest strength gain over TF00 are wanted with good conductivity. | 345 | 435 | 20 | 128 HB | 82 % IACS |
TD02 and precipitation hardened | Intermediate step-aged temper when a little more strength than TF00 is needed but some bending ductility must remain. | 385 | 455 | 18 | 135 HB | 81 % IACS |
TD04 and precipitation hardened | Highest-strength wrought temper: use for heavily loaded electrode shanks, contact arms and switchgear pins where >430 MPa yield is required. | 440 | 495 | 14 | 150 HB | 80 % IACS |
What is QCr0.5-M?
QCr0.5-M is QCr0.5 heat treated to M — softest condition for deep forming, spinning or subsequent solution treatment; low strength and only moderate conductivity if Cr is partly in solution. QCr0.5-M has a yield strength of 100 MPa (14.5 ksi) and a tensile strength of 250 MPa (36.3 ksi) — weaker than 87% of copper alloy grades. Elongation at break is 40% and the elastic modulus is 117 GPa (17 Msi). QCr0.5-M has a density of 8.89 g/cm³ (0.321 lb/in³), heavier than 72% of copper alloy grades. It melts at 1,070°C (1,958 °F). TF00 is the default condition FabDigit quotes; M is available on request or by drawing note.
Advantages
- High service temperature — 300°C (572 °F), better than 85% of copper alloy grades
- Ductile — tolerates forming and impact — 40%, better than 84% of copper alloy grades
- Forms and bends easily — 80/100, better than 83% of copper alloy grades
- Conducts heat well — 240 W/m·K (138.7 BTU/hr·ft·°F), better than 81% of copper alloy grades
- High electrical conductivity — 55 % IACS, better than 80% of copper alloy grades
Limitations
- Low strength — 100 MPa (14.5 ksi), worse than 87% of copper alloy grades
QCr0.5-M properties
Typical room-temperature values for QCr0.5-M; 10 are specific to this condition. Other listed values are QCr0.5 reference data and may not represent this condition. Bars are the position among copper alloy grades.
Physical3
QCr0.5-M has a density of 8.89 g/cm³ (0.321 lb/in³), heavier than 72% of copper alloy grades. It melts at 1,070°C (1,958 °F).
Mechanical13
QCr0.5-M has a yield strength of 100 MPa (14.5 ksi) and a tensile strength of 250 MPa (36.3 ksi) — weaker than 87% of copper alloy grades. Elongation at break is 40% and the elastic modulus is 117 GPa (17 Msi).
Thermal6
QCr0.5-M is rated for continuous service to 300°C (572 °F). It conducts heat at 240 W/m·K (138.7 BTU/hr·ft·°F), better than 81% of copper alloy grades. Thermal expansion is 17.6 µm/m·K (9.78 µin/in·°F).
Electrical3
QCr0.5-M conducts electricity at 55 % IACS, better than 80% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is good (62/100), worse than 57% of copper alloy grades.
Sustainability4
Producing a kilogram of QCr0.5-M takes about 55 MJ of energy and emits 3.8 kg of CO₂ — less than 72% of copper alloy grades. Typical recycled content is 35%.
Manufacturability8
QCr0.5-M's machinability is fair (35/100, better than 51% of copper alloy grades); weldability poor (30/100); formability very good (80/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with QCr0.5-M
Is QCr0.5 easy to machine?
Gummy in the solution-treated state — machine in TF00/TH tempers with sharp positive-rake carbide, high speed, light feed and flood coolant; expect roughly a quarter of free-cutting brass throughput.
Can QCr0.5 be welded?
Fusion welding is difficult (very high conductivity, tenacious Cr₂O₃ film) and locally over-ages the alloy; prefer GTAW with high preheat-free high current and argon, or use brazing/mechanical joints and re-age if strength matters.
Can QCr0.5 be formed, bent or molded?
Form, bend, spin or upset in the TB00/M condition, then solution treat (~980 °C, water quench) and age 2–4 h at 450–480 °C for full properties.
What surface finishes work on QCr0.5?
Not anodizable; use bright dipping, chemical passivation, or Ni/Ag/Cr electroplating — silver plating is common for contact surfaces, and heavy plating bakes must stay below the ageing temperature.
QCr0.5 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 |
|---|---|---|
| CrGB/T 5231 QCr0.5; C18200 range is 0.6–1.2 | 0.4 – 1.1 | 0.65 |
| Siimpurity limit | ≤ 0.1 | — |
| Feimpurity limit | ≤ 0.1 | — |
| Pbimpurity limit | ≤ 0.05 | — |
| Znimpurity limit | ≤ 0.05 | — |
| Cubalance, ≥98.6 % including Ag | balance | — |
QCr0.5-M — frequently asked
What is QCr0.5-M used for?
QCr0.5-M is typically used for welding electrodes, switch contacts, rotor bars and high-conductivity fasteners. In short: softening resistance to 400 °C; standard welding-electrode copper; 82 % IACS with strength.
What is the yield strength of QCr0.5-M?
QCr0.5-M has a typical yield strength of 100 MPa (14.5 ksi) and a tensile strength of 250 MPa (36.3 ksi) — weaker than 87% of copper alloy grades. Strength varies by condition: see the 8 listed tempers.
Is QCr0.5-M easy to machine?
Not especially — machinability is rated fair (35/100, better than 51% of copper alloy grades). Gummy in the solution-treated state — machine in TF00/TH tempers with sharp positive-rake carbide, high speed, light feed and flood coolant; expect roughly a quarter of free-cutting brass throughput.
Can QCr0.5-M be welded?
Not readily — weldability is rated poor (30/100). Fusion welding is difficult (very high conductivity, tenacious Cr₂O₃ film) and locally over-ages the alloy; prefer GTAW with high preheat-free high current and argon, or use brazing/mechanical joints and re-age if strength matters.
What surface finishes work on QCr0.5-M?
Not anodizable; use bright dipping, chemical passivation, or Ni/Ag/Cr electroplating — silver plating is common for contact surfaces, and heavy plating bakes must stay below the ageing temperature.
Can QCr0.5-M be formed, bent or molded?
Form, bend, spin or upset in the TB00/M condition, then solution treat (~980 °C, water quench) and age 2–4 h at 450–480 °C for full properties.
What is the maximum service temperature of QCr0.5-M?
QCr0.5-M 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 QCr0.5-TF00 and QCr0.5-TB00?
TF00 is the default condition — the standard stocked condition: best balance of ~420 MPa strength with >80 % IACS conductivity — the classic RWMA Class 2 resistance-welding electrode temper. TB00: supersaturated, soft and ductile — pick when the part must be formed or machined before precipitation ageing. Yield strength is 315 MPa in TF00 versus 90 MPa in TB00.
Sources
- ASTM B187/B187M Copper Bus Bar, Rod and Shapes — ASTM (2020)
- CDA Alloy C18200 Chromium Copper datasheet — Copper Development Association (2023)
- ASM Handbook Vol.2 — Properties of Copper and Copper Alloys — ASM International (1990)
- RWMA/ANSI Resistance Welding Electrode Material Classes (Class 2) — AWS/RWMA (2016)
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.