Prop hardening questions

[John Beardslee]

Even though it's not the very best, going straight to the hardening stage without the annealing stage will improve your props shape holding ability and make them less prone to edge dings. I don't recomend annealing finished props though. That process is pretty severe and would distort them so I would skip it. As has been said, for best material performance 1rst anneal, 2nd do your prop work, 3rd harden. And skip the piss, use salt water for annealing. LOL

As for 1/2 hard or 3/4, octura props are likely about 1/2 hard as cast. Try to find some data on tensil strength and elongation as it relates to hardness in this material.

Hi Joe,

The specs I worked from for 2% BeCu was 70,000 psi as cast and 135,000 psi at full hard after heat treating. I which I could remember the Rockwell numbers or find my notes/logs that had them but so far I can't find them. I don't know if the industry standards are started from dead soft annealled or at an as cast condition or from a rolled billet to generate a scale of 1/4, 1/2 or 3/4 hard. I use these only because I know magnesium and silver solder is scaled that way, yet alumium has a different scale ie: T3, T6 etc.

Thanks, John

 

[Michael Caruso]

One thing I think would be useful for heat racing props would be to develop a recipe for heat treating BeCu to less than full hard ie: 1/2 or 3/4 hard or ? This may allow slight tweaking or bending without cracking or breaking the blades.

This is exactly what my intentions were. I don't want my props over-aged and brittle. Just hard enough to help hold pitch.

So to go this direction I take it the annealing is still neccessary? What would be your gut approach to this?

Good info here. John - I will be calling you up when I more of my set up together.

Doug

45 years ago and old guy told me if I want to anneal very small parts like out props to use boring bar chips. I used the boring bar chips to anneal good grade Blue Point hardened Allen set screws so I could drill them with a .018-.020" drill bit. Great way back in the day to modify racing engine oil systems so the rod and main bearings would live. Automotive machine shops that bore cylinder blocks oversize will have plenty for every one in boating for free. All you would have to do is ask them for some. LOL I forgot all about using it for years until this prop heat treating came up and it does a great job. I will get some from one of my friends this week and try it on a hurt M-645 will report. These chips are real small as most cast iron cylinders get bored approx .024" oversize total diameter. So the chips can be half size .012" or .006". I think it will do a better job than steel shot as far as even cooling unless the steel shot is very small as the boring bar chips.

Just thinking it might not Shock the prop material as quick but more evenly. Dunno?

Hi Mike,

I sounds like you may be getting the annealing process for ferrous metals confused with the process for non-ferrous metals. Ferrous metals (iron based) require a slow cooling from high temps to anneal and non-ferrous metals require a fast cooling from high temps to anneal.

Thanks, John

John,

Yes I did and thanks for pulling back on the correct path.

Mike

 

[Michael Caruso]

https://www.intlwaters.com/gallery/albums/userpics/10068/Prop%20Heat%20Treat.pdf

Hi Terry,

Thanks https://www.intlwaters.com/gallery/albums/userpics/10068/Prop%20Heat%20Treat.pdf

Mike

 

[Michael Caruso]

Octura's alloy is 20C, also from page 4 of my above post:

"Because most salts will attack copper beryllium at

temperatures in the solution annealing range, solution
annealing should not be performed in a salt bath."

Thanks again Terry

 

[Mike Bontoft]

Forgot I had posted the question on ovens. Thanks for the replies. Think I will try a repair with the controller mentioned.

Cheers

 

[Michael Caruso]

Forgot I had posted the question on ovens. Thanks for the replies. Think I will try a repair with the controller mentioned.

Cheers

Mike,

I found this in papers I down loaded last year while I was cleaning up my basement work shop. If I could have figured out how to attach a word doc. I would have so everyone could read easy. Here are the address's

http://materion.com/Products/Alloys/ToughMetCopperNickelTinAlloys.aspx?gclid=COHsmfvpproCFcZFMgodmVAAKQ

http://materion.com/ResourceCenter/TechnicalPapers/CopperBerylliumWroughtAlloysTechnicalPapers.aspx

http://materion.com/~/media/Files/PDFs/Alloy/Tech%20Briefs/AT0015-0311%20-%20Tech%20Briefs%20-%20Heat%20Treating%20Copper%20Beryllium%20Parts

Bottom one is heat treating

 

[Mike Bontoft]

Thanks Michael, much appreciated