How to anneal brass

A. If you can pressurize the oven with inert gas like argon or nitrogen I think it will work as long as all the oxygen is vented. A simpler way is to seal the sheet in a Stainless steel bag that is produced for this purpose.

A. I am unaware of any MIL specification for the heat treatment of alloy 270 (C27000, Yellow brass 65Cu-35Zn). ASTM B601, "Standard Classification for Temper Designations for Copper and Copper Alloys,Wrought and Cast", specifies resultant properties in a generic fashion but not process details. E.g., H02 indicates cold worked to ? hard, OS035 indicates annealed to an average 0.035 mm grain size.

ASTM B36, Standard Specification for Brass Plate, Sheet, Strip, And Rolled Bar, gives tensile strength and hardness values for C26800 (64Cu-36Zn) and C27200 (63Cu-37Zn) in various tempers. The values are nearly identical (except for spring hard) and should serve for C27000.

To specify an annealing, one needs initial material info and an objective. What is the grain size, the amount of prior cold working, the desired grain size and the amount of further cold working to be performed? Are you certain of the need for annealing? It will reduce the yield strength up to 80% dependent upon initial value. Typical annealing temperatures range from 425 to 750 °C. A relatively low temperature anneal, 1 hr at 300 °C, will yield a small grain size (better for polishing), while a higher temperature, 500 °C, may be necessary to achieve a 50% elongation via cold working. A protective atmosphere is recommended for higher temperatures to avoid oxidation. Testing of grain size or hardness for comparison with values from ASTM B36 or the references below is recommended.

I didn't find data on annealing C27000 to improve conductivity. From data for copper, I would guesstimate an improvement < 4 relative %, e.g., from 26% to 27% IACS.

For more annealing details and other properties, see ASM Metals Handbook Vol. 2 'Properties and Selection: Nonferrous Alloys and Special-Purpose Materials' [affil link on Amazon]. Physical properties of C27000 in cold worked (1/8, 1/4, 1/2, hard, extra hard and spring hard) and annealed (of various grain sizes) tempers can also be found on the Copper Development Association site at www.copper.org.

A. "Annealing is the process of reducing stress within metal by heating it to a prescribed temperature. Industrially this is done in a furnace where the temperatures can be monitored mechanically. in the studio it is more common to anneal with a torch. Temperatures are gauged by the color progression of the metal, with a dimly lit area being best suited for this purpose. Paste flue may be painted onto the metal to serve as a temperature indicator: it is clear at 1100 °F (593 °C). If quenching in a pickle, beware of dangerous fumes and splashing acid. A safer method is to quench in water then slide the work into the pickle."
      --The Complete Metalsmith by Tim McCreight .

Bronze Heat to a medium red; quench when the Copper redness disappears.

It is important to use the proper quench, I'd suggest the use of vegetable oil (take care it will ignite when you initially quench the piece!), I'm suggesting vegetable oil because it will cool the work slower than water and will protect the metal from oxidizing too much when heated. You can generally use whatever vegetable oil you can purchase at the local grocery store.

Annealing is a very important process to use when working non-ferrous metals as it reduces the stresses in the metals and keeps it from breaking. Don't anneal, and you run a very great risk of breaking the handle, you can (and I do suggest) working the handle cold and annealing as you go. Get a chunk of brass from the hardware store and get the feel of what I'm talking about before you do it.

A. The discoloration is coming from one or both of two causes. Either there is some organic film, like a thin oily layer, left on the wire after drawing: or the wire is getting hot enough to discolor in the furnace atmosphere. If it is the first, then cleaning is vital. If the latter, then changing the atmosphere would be wise. We age beryllium copper wrapped in aluminum foil while bleeding nitrogen through the wrapped assembly, and it works well. Perhaps something akin to that would assist you.

? Hi Erin. Can you flesh out your inquiry a bit? Govind's copper wire can be electrocleaned then rinsed in DI water, or it can be cleaned with perchlorethylene in a vapor degreaser. Other items can probably be cleaned with pumice [on eBay or Amazon] and a scrub brush [on eBay or Amazon], then rinsed. But if there's no residue, what will stop it from immediately tarnishing?

Are you referring to before or after an annealing operation, or to the more general case of just removing soil & oil from copper? Thanks.

Regards,