Brass Inspection Criteria

Can you give more information such as why it is important? Optical microscope. Laser scanner. Ultra sound. ?

We are a stamping company, we are using brass to stamp a part for one of our customers, they have to polish the part to have shinny finish, we had a problem when the brass used caused some kind of orange peel after it was polished, we identified some differences on the surface when two samples of different mills were inspections, we used just a microscope to do the inspection, but it is not measurable method, I would like to have a practical inspection method to determinate the surface condition avoiding orange peel condition.

Thank you for the advise,

Joe

This will indicate more zinc being used to make a cheaper type of brass. Don't use this supplier again unless they under take to guarantee the quality. Have them replace the faulty metal. Do an acid test with a little hydrochloric acid it will show up this form of cheating. The extra zinc will dissolve out from the copper. It fizzes. When you are polishing it is showing up this problem.

THANK YOU FOR YOUR INFROMATION.

The actual chemical composition of the brass with problems is as following:

Cu - 71.5 %

Fe - .05%

Pb - .07%

Zn – REM

Average grain size .025 to .04 mm

The actual chemical composition of the brass without problems is as following:

Cu - 71.38 %

Fe - .022%

Pb - .003%

Zn – REM

Grain size .050 mm

The grain size could be a difference on the metal surface?

Could be the way it was rolled out, and from what thickness to that you purchased. It could have been over worked. The composition is too alike to be the zinc. What polish do you use. (without seeing the metal it is a hard one to diagnose out right) any chance of a couple of photos? Please.

Joe:

The alloy you are using is essentially Cartridge Brass (CDA26000) and the chemistry may be the key to the difference in surface finishing but the responsible element may be the Fe content; not Zn. All of the alloys in this series are susceptible to dezincification and stress corrosion cracking and Fe increases that susceptibility. While we don't know the polishing process used by your customer, it is possible that the "orange peel" is dezincification, which can be caused mechanically and would be accelerated by exposure to strong acids and bases or either soft or high salinity water.

Since you asked about grain size and direction, one might be able to use ultrasonics as a means to compare relative grain size and rolling directions. Although ultrasonics are normally used to detect cracks and other surface and subsurface defects, grain boundaries are also detectable. In a normal test, grain reflection would be considered "grass" but the amplitude and period of that "grass" could be used for grain measurements. It would take some experimentation and establishment of acceptable standards with which to compare but it probably could be done.

yes we are using C2600 material it is rolled and attached you can see some photos about the problem.

The third photo says plated what sort of plating? It is likely that the plating process is the cause. Is it the actual plating peeling off? Ie brass showing through. Or an iregular surface (plating in tact) it is hard to tell from the photo.

0.05% iron is unlikely to cause this situation.

Maybe it could be BRASS CASTING.

Can u confirm teh same. Also please try ROLLED BRASS

I am intrested on this problem.

Dear friend,

Best chemical composition of Brass is :

cu:88%

zn:11%

Impurities: 1%-Pb / Fe/ Sb etc.

You send 50 grm of brass piece in chemical lab. and test.

Regards

Hi Joe

I don't think your problem is with the chemical composition of your alloy. How closely do you monitor the temperature of your alloy prior to stamping ( assuming you are hot stamping) If the temperature is too hot or held for too long considerable grain growth can occur and this will ultimately affect the surface Finnish and produce the orange peel effect you describe.

Hope this helps

Abdul

I agree on Hot stamping will be easyly happened orange peel on surface.