What is DTD 197A / BS B23?
DTD 197A is a Ministry of Aviation specification applied to aerospace applications such as landing gear bushings and bearings. The alloy CuAl10Ni5Fe4, superseded by BS 2B 23, has high strength and excellent wear and anti-galling properties, plus good corrosion resistance in saline conditions. It is cross-referenced with BS 2874 CA104, ASTM B150 C63000 and BS EN CW307G.
Should you specify DTD 197A / BS B23?
You normally arrive at DTD 197A, BS B23 or CA104 through an old drawing rather than a new design. All three are legacy British designations for the same wrought nickel aluminium bronze, CuAl10Ni5Fe4, and all three appear on the same equivalents list as ASTM B150 C63000 and BS EN CW307G.
For a repair or a spare against a legacy drawing, the practical route is to order the current standard - CW307G in Europe or C63000 in the United States - and have the certificate cross-referenced to the legacy designation. Confirm with your quality department which designation must appear on the release note before the melt, not after.
For a new design, go straight to CW307G or C63000, or to DEF STAN 02-833 if the part is destined for a UK naval programme. There is no benefit in writing an obsolete designation onto a new drawing.
The property set is genuinely good: excellent wear, fatigue and corrosion resistance with high mechanical properties, which is why the alloy is still in service across aerospace, marine and power applications decades later.
Best for repairs and spares against legacy DTD 197A, BS B23 or CA104 drawings, supplied and certified against the current CW307G or C63000 standards.
DTD 197A / BS B23 quick reference
Typical, indicative values as published by Copper Alloys Ltd. Typical values are not specification limits, and vary with product form, section size and temper.
| Alloy type | Wrought - Wrought nickel aluminium bronze |
|---|---|
| Nominal composition | CuAl10Ni5Fe4 |
| Tensile strength (typical) | 640 N/mm² |
| Proof / yield strength (typical) | 270 N/mm² |
| Elongation (typical) | 15 % |
| Hardness (typical) | 180 HB |
| Izod impact (typical) | 23 J at 20 °C |
DTD 197A / BS B23 typical physical properties
Key features of DTD 197A / BS B23
- One of the most popular complex nickel aluminium bronzes.
- Excellent wear, fatigue and corrosion resistance with high mechanical properties.
- Good corrosion resistance in saline conditions.
- Widely used in aerospace and marine applications.
DTD 197A / BS B23 applications
Industrial
- Plunger tips
- Corrosion resistant articles
- Hydraulic bushings for earth moving equipment
- Valve balls and bushings
Power
- Condenser tube for power stations and desalination units
- Shafting, pump parts, cams and gears
- Heat exchanger flanges, headers and tanks
- Welded piping systems
Aerospace
- Landing gear bushes and bearings
- Wing flap bearings
Automotive
- Valve guides and seats
Marine
- Ship propellers
- Pump parts
- Nuts and bolts
- Impellers, valves and valve stems
DTD 197A / BS B23 equivalent specifications
Frequently asked questions
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Information provided is for reference only
The composition, mechanical and physical figures on this page are typical, indicative values compiled from published Copper Alloys Ltd datasheets to aid early-stage material selection. They are not specification limits and are not engineering, procurement, safety, regulatory or design advice.
Before specifying, purchasing or using any material, confirm the requirements against the current controlled version of the relevant standard and obtain a certified material test report and written technical confirmation from Copper Alloys Ltd or another qualified foundry.