Tell difference between bronze and phosphor bronze

ltcom

ltcom

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I found via a search a website Vyv Cox linked to showing the different colours of these alloys, but my metal looks all the same.
I have been given a lot of stock metal of bronze/ phosphor bronze but i need to be able to tell the difference before I stick a piece in my lathe.
Searching seems to say that unless i have a mass spectrometer I am out of luck.
Are there practical ways I can tell the difference? Cheers.
 
ltcom said:
I found via a search a website Vyv Cox linked to showing the different colours of these alloys, but my metal looks all the same.
I have been given a lot of stock metal of bronze/ phosphor bronze but i need to be able to tell the difference before I stick a piece in my lathe.
Searching seems to say that unless i have a mass spectrometer I am out of luck.
Are there practical ways I can tell the difference? Cheers.
Click to expand...
Sorry, no, there is not a practical simple way and Viv's web page is probably the best advice. If the item you are going to produce is safety critical and you want to use the material you have then the best you can do is an annual inspection for signs of dezincification.

Www.solocoastalsailing.co.uk
 
Plum said:
Sorry, no, there is not a practical simple way and Viv's web page is probably the best advice. If the item you are going to produce is safety critical and you want to use the material you have then the best you can do is an annual inspection for signs of dezincification.

Www.solocoastalsailing.co.uk
Click to expand...
Bronzes do not suffer from dezincification. The are alloys of copper and tin, in the main containing little or no zinc in the first place.
 
VicS said:
Bronzes do not suffer from dezincification. The are alloys of copper and tin, in the main containing little or no zinc in the first place.
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You are right for copper tin alloys, but my point was that as the op does not know what alloys he has some my be susceptible to dezinc,. Manganese Bronze or Admiralty bronze, for example , do suffer.

Www.solocoastalsailing.co.uk
 
Scrappies might have an x-ray fluorescence (XRF) spectrometer, which will do the job. A mass spectrometer (organic or inorganic) is a different beast and will either not do what you want (organic MS) or be somewhat OTT (inorganic MS). If you have a university science or materials dept they may be able to assist with an XRF spectrometer or an electron microscope fitted with an XRF detector but they will likely want some beer tokens.
 
Thanks for the info. The only other ideas I thought of were a home brew electrolysis experiment (no idea if or how that would tell me phosphor bronze from bronze), dropping a wedge on the metals from a known height (is phosphor bronze harder?) or measuring the density of equal weights of samples cut off.
Any thoughts on those ideas?
Will see if local scrap yard has a xray spectrometer.
 
Assuming that the alloys all have the same colour it will be very difficult. The phosphorus content is very low. Its main function is as a deoxidant, removing porosity and tin oxides from the bronze. Without a metallurgical microscope you are unlikely to see the difference. The strength of the phos bronze should be greater but it will take ingenuity to test.
 
ltcom said:
I found via a search a website Vyv Cox linked to showing the different colours of these alloys, but my metal looks all the same.
I have been given a lot of stock metal of bronze/ phosphor bronze but i need to be able to tell the difference before I stick a piece in my lathe.
Searching seems to say that unless i have a mass spectrometer I am out of luck.
Are there practical ways I can tell the difference? Cheers.
Click to expand...

Just a thought, if you have 2 materials and you know one of them is phosphor bronze, you may be able to tell by the swarf. If it chips easily, it won't be phosphor bronze. Generally, I use pb102 which when you face off has slightly more red colour than other bronzes, and you can a smoother finish at slow speeds. There's a small chance I may be able to help if I could compare the two, but I guess you want to be 100% sure.
 
colhel said:
Just a thought, if you have 2 materials and you know one of them is phosphor bronze, you may be able to tell by the swarf. If it chips easily, it won't be phosphor bronze. Generally, I use pb102 which when you face off has slightly more red colour than other bronzes, and you can a smoother finish at slow speeds. There's a small chance I may be able to help if I could compare the two, but I guess you want to be 100% sure.
Click to expand...
Thank you. That is useful . I will rely if (and when) I have found out what is what and have some swarf to show. Cheers
 
Just another thought and one im looking into, is testing the potential against a reference metal. I think i have a reference chart for bronze alloys using ag-agcl reference cell in Collier’s boat owners guide to corrosion. Ill report back.
 
The refernce Collier cites is from ABYC E-2 (Table 4-1). Unfortuately it does not include data specific to phoshphor bronze but even so, it offers little more than an educated guess to distinguish your alloy in question. Furthermore you’d need to replicate the exact test environment used to create the table. It may be interesting to observe potentials far outside Table 4-1 data. I’m not wasting anymore time but here is what I found for those inclined. You can use a milspec zinc anode for a reference cell vs. silver chloride but you need a correction factor for these tables which I dont have off hand.
Brasses range 240mv-370mv. Bronze range is 260mv-310mv
Below is a summary exclusive to The Boat Owner’s Guide to Corrosion by Everett Collier which was required reading for ABYC’s Marine Corrosion course.
Brass=Zinc primary alloy
Bronze=Tin is primary alloy
Brasses- Red, cartridge, yellow, muntz metal, admiralty, naval, aluminum, and ”manganese bronze” which is actually a 60:40 cast brass. Note: although brass is susceptible to dezincification and stress crack corrosion, it greatly diminishes when zinc is less than 15%.
Bronzes-phosphor, aluminum, silicon, gunmetal
 
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