Resource Library

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.


What is the most attractive visual feature of nickel silvers?

They can be polished to a silvery appearance.

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.

What is the safe limit for ammonia in contact with brass to prevent stress corrosion cracking?

There is no acceptable limit – it is essential that internal stresses are removed as far as possible by a stress relief anneal at 250-350oC for 1/2 to 1 hour.

Is post weld heat treatment required when welding copper-nickel alloys?

Post weld heat treatment is normally unnecessary.

What is the solution treatment temperature?

This term applies to alloys such as Cu-Be and Cu-Cr which are strengthened by age (precipitation hardening). It is the temperature (900-1000C) to which the alloys are heated prior to quenching and ageing.

Is there a difference in properties between continuous cast versus centrifugally cast aluminium bronze?

Yes, in the EN specification the properties are quoted separately for continuous cast (GC) and centrifugally cast (GZ) conditions.

What is TN-C-S?

TN–C-S is the most common type of earthing employed in the UK.  The name, defined in French in European standards, indicates that the earth (Terre) and Neutral are connected together by the supplier, that the earth and neutral are Combined on one conductor in the supply system and that they are Separated at the consumer’s point of common coupling.  This separation of earth and neutral is maintained throughout the installation.  In other words, the neutral is treated is the same way as the phase – insulated and isolated from earth throughout.

This is important because keeping the neutral and earth separate within the building reduces stray currents in the earthing system, and improves electromagnetic compatibility.

Other types of earthing system are described in section 3.2 Earthing on LV Systems and Within Premises in Pub 119 Earthing Practice.

Is wrought fire refined copper (C104) available?

No, C104 is regarded as low grade due to impurities. All copper is refined (purified) by electrolysis.

What advantages do copper alloy cages offer?

Copper alloy mesh cages resist predator attack, prevent fish escapes, offer good corrosion resistance and a low susceptibility to marine organism attachment. They provide improved water flow and circulation, and help maintain higher oxygen levels which gives a healthier environment for the fish. This results in higher yields and lower maintenance, and the copper alloy is infinitely recyclable at the end of its life.

What makes a sprinkler head activate?

When the sprinkler head reaches a certain temperature it will activate.