Q Can brass fittings be cleaned with industrial cleaners?
A Yes, but not cleaners that contain ammonia.
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Q What is common brass?
A 64/36 brass.
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Q What is the annealing temperature for brass?
A 500-550°C.
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Q Which copper alloy has the highest ductility?
A 70/30 brasses CZ106 (CW505L).
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Q Are the brasses much weaker than steels?
A No, high strength brasses have tensile strengths up to 770 MN/m2 which is much better than many steels.
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Q What are the gilding metals and what are they used for?
A Copper-zinc alloys (brasses) with up to 20% zinc.
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Q Which brass would you recommend for fittings for tubes which have to resist dezincification?
A CZ 126 (CW707R).
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Q I am a jewellery designer interested in using brass wire which has a white colour and good corrosion resistance, what should I use?
A Use nickel silver wire CuNi10Zn27 (CW401J). This is used in dental applications, model making and for jewellery.
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Q I am considering making a heat exchanger from either 70/30 brass or austenitic stainless steel. What are the thermal conductivities of these materials?
A For brass, 120W/m°C, and for stainless steel, 17W/m°C. As can be seen, the brass has a conductivity seven times better.
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Q I am an architect looking for brass tubes in order to make handrails for a listed building where colour and appearance are important. What should I use? How may the surface be preserved?
A The high copper brasses (gilding metals) such as CuZn10, CuZn15, CuZn20 and CuZn30 have a range of colours and are well suited for this application. Obtain samples to find the exact colour.
For handrails which come into contact with the public, the best protection would be given by periodically waxing using a natural wax such as Carnauba or beeswax. For rails which are only subject to atmospheric attack a lacquer such as Incralac should be used.
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Q Does brass become brittle like mild steel at cryogenic temps?
A No, brass retains its toughness at low temperatures.
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Q A brass water fitting in dezincification resistant brass has been brazed. Should it be re-heat treated?
A Yes, heat to 500 to 525°C, hold for two hours and slow cool, to ensure an all alpha structure.
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Q An engineering report suggests that Stress Corrosion Cracking (SCC) is a problem in brass tubes. What steps may be taken to avoid SCC?
A SCC occurs due to the combined effect of stress and corrosion. The stress may be removed by a stress relief anneal at 250 to 300° C for ½ to 1 hour.
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Q A 3% leaded brass tube, used to make an electrical fitting, cracked on crimping. Why?
A Lead reduces the ductility of brass so use a tube with 1% lead.
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Q Brass is said to be non-magnetic, but a sample reacts to a magnet. Why?
A Probably due to the high iron content from recycled scrap. If a non-magnetic copper alloy is required use a nickel aluminium bronze to Def Stan Specifications (were NES).
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Q I have a brass table top which has been scratched. How can I restore the surface?
A By hand polishing (buffing) using a soft abrasive such as T-Cut or Brasso. Follow this by waxing with a natural wax.
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Q I wish to restore a copper canopy on an old building to its original condition. How can I do this?
A Stages:
(a) Remove surface oxide with dilute (10%) hydrochloric acid
(b) Neutralise with bicarbonate solution (lye)
(c) Seal by chromate conversion
(d) Lacquer
(e) Wax
(f) Clean with detergent annually.
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Q Is Naval Brass suitable for use in a swimming pool with chlorinated water?
A Dry chlorine and very low concentrations of chlorine solutions, such as the dosing of seawater to prevent marine fouling and biocide additions made to swimming pool water, present no difficulties and no corrosion problems are expected.
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Q I am making bowls and plates out of brass. Is there anything in brass which means that you cannot put food on it? Can I just wax them or do I need to coat them with something?
A No coating at all is needed. It would rub off during use and washing. The wax would affect the taste of the food and need reapplying. Brass is commonly used in Asia for food bowls. Brass is not suitable for food storage; acidic food would lead to corrosion.
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Q I have been asked for 'Coining Brass'. What is it?
A Coining is closed die squeezing (as in making coins) and applies to any of the cold forming brasses: 90/10, 85/15, 80/20, 70/30. Should be OK to use 1/2 hard , but anneal if necessary.
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Q I am using CW614N (CZ121) to make machined components for a major motor manufacturer. The process results in about 3 tonnes per week of brass swarf which is contaminated with machining oil. Could this still be recycled?
A Yes, brass swarf is very valuable and should be recycled. The brass industry relies on recycling for its survival; they will be able to clean the oil from the swarf before remelting it.
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