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Is it possible to heat treat aluminium bronze CW307G (CA104) to improve its corrosion resistance?

Yes, this is covered in Def Stan 02-833. For extruded rods and sections of size 40mm and below, an anneal at 740°C plus or minus 20° followed by air cooling is carried out. This mandatory heat treatment is to eliminate phases which are likely to give rise to selective corrosion in sea water.

With respect to the MOD Defence Standard 02-879 Part 2 Forgings, what do the terms Class 1, Class 2, Class 3 and Class 4 mean?

 

  • Class 1 is a forging whose failure would lead to uncontrollable flooding, the total immobilisation of the vessel or serious harm to personnel.(e.g. First Level systems in submarines).
  • Class 2 is a forging whose failure would lead to severe but controllable flooding, the serious disruption of weapon systems, main propulsion machinery, or its attendant auxillaries, including generators
  • Class 3 is a forging whose failure does not constitute an immediate, significant hazard.
  • Class 4 is a forging which is used for forging stock only.

 

Is Naval Brass CZ112 (1-1.4% tin) still available?

No, the nearest alloy to Naval Brass is a leaded brass CW712R, available in rod, bar and wire. For sheet and plate the UNS Alloy C46400 (0.5 to 1.0% tin ) is used.

With respect to the MOD Defence Standard 02-879 Part 2 Forgings, what do the terms Class 1, Class 2, Class 3 and Class 4 mean?
  • Class 1 is a forging whose failure would lead to uncontrollable flooding, the total immobilisation of the vessel or serious harm to personnel.(e.g. First Level systems in submarines).
  • Class 2 is a forging whose failure would lead to severe but controllable flooding, the serious disruption of weapon systems, main propulsion machinery, or its attendant auxillaries, including generators
  • Class 3 is a forging whose failure does not constitute an immediate, significant hazard.
  • Class 4 is a forging which is used for forging stock only.
Are weld repairs permissible on Class 1 and Class 2 nickel aluminium bronze forgings produced to Def Stan 02-833?

No, the rectification of defects by welding is not permitted on Class 1 and Class 2 (high integrity) forgings.

A drawing specifies TUNGUM for a pipe. What is TUNGUM?

TUNGUM is a trade name for aluminium-nickel-silicon-brass. CW700R (CZ127).

Are weld repairs permissible on Class1 and Class 2 Forgings produced to Def Stan 02-879 Part 2?

The rectification of defects by welding is not permitted on Class 1 and Class 2 forgings.

Are weld repairs permissible on Class1 and Class 2 Forgings produced to Def Stan 02-879 Part 2?

The rectification of defects by welding is not permitted on Class 1 and Class 2 forgings.

Are 90-10 and 70-30 copper-nickels susceptible to stress corrosion cracking?

They do not experience chloride or sulphide stress corrosion. They have a high resistance to ammonia stress corrosion compared to other copper alloys and do not require a stress relief anneal for seawater service.

Are 90-10 welding consumables available for welding 90-10 copper-nickel?

They are available but 70-30 copper-nickel consumables are preferred for welding both the 90-10 and 70-30 alloys due to superior deposition characteristics.

Are copper-nickel alloys susceptible to the attachment of marine organisms in seawater?

Copper-nickel alloys can harbour slimes, but the attachment of macro-organisms—such as marine grasses and shellfish—is impaired. If these do become attached under quiet conditions, adherence is poor and they can be easily removed mechanically.

Adhesion of marine organisms is a major issue in fish farming. Do copper alloys suffer from attachment of micro and macro-organisms?

Copper alloys can harbour slimes, but the attachment of macro-organisms—such as marine grasses and shellfish—is impaired. If these do become attached under quiet conditions, adherence is poor and they can be easily removed mechanically. Copper alloy mesh prolongs the intervals between periodic cleaning, thus promoting a cleaner and healthier environment for aquaculture.