Silver solder strength

[Herbiev]

Just wondering if the strength of silver soldered joints are proportional to the amount of silver in the solder sticks. I need to solder some rods on to eccentric straps for the Westbury engine and was thinking of using 45% silver solder

 

[goldstar31]

I'm not a metallurgist but the melting point of the silver solder rises after the joint is made. I assume the silver disappears into the parent metal leaving the stronger alloys as the joint.

I may get shot down but silver soldered joints were the basis of orthodontics and jaws have a mighty strong bite.

However, silver soldering was the joining method adopted by Ned Westbury and the rest of the old 'greats' You might even getaway with soft soldering with lead based solders. However, don't do silver soldering on top of lead. Things can get quite nasty!

Does this help?


Norman

 

[Herbiev]

Thanks Norman. I shall give it a go this weekend.

 

[bazmak]

45% is the best for our type of work Herbie

 

[Blogwitch]

I use a 30% silver content solder, ( Easiflo with Tenacity 5 flux), a slightly higher melting temperature than 45%, but it does give a stronger and harder joint.

This is copper pipe soldered to a mild steel fitting showing an attempt to test until destruction just ended up with this result. Much stronger than one of the parent metals. The copper pipe eventually just tore away but left the soldered joint perfectly intact.

I use this for all my silver soldering, even on fabrications as I find that the remelt temperature a lot higher than the normal melt temperature, so I do not have to use many different silver contents and temperature ranges.


John

 

[Herbiev]

Thanks Baz and John. According to your post John a lower silver content gives higher strength. Is this correct?

 

[doubletop]

Thanks Baz and John. According to your post John a lower silver content gives higher strength. Is this correct?

And more cash stays in your wallet...

 

[Herbiev]

And more cash stays in your wallet...

Not for long unfortunately

 

[Blogwitch]

Herb,

I am no metalurgist, but I do know what works for me and has worked very successfully for many years.
What I have shown and told you about has been my mainstay for at least 40 years, and I can't recount a single failure due to solder joints giving way (if done correctly).
Over the last few years, due to H&S issues a lot of solders have either had things added or taken away (Cadmium being one of the usual ones), usually to the detriment of the finished joint or getting them flowing correctly. The amount we use silver solder, you would need to be chewing the old stuff for years to cause you any deathly harm. When working with aircraft, I reckon 90% of the nuts and bolts we used were covered in Cadmium, so the damage has already been done, but I do wear a dust mask and well ventilated when soldering, just in case it does shorten my life by a minute or two.
When this sort of thing started to happen, I bought up old stocks of silver solder, in wire, rod and sheet form, just changing flux as and when they come out with a better one for stainless steel, as I find that if it works well with stainless, all other solderable materials will present no problems. I now have enough stock to last two lifetimes, even if Cadmium doesn't get me.

John

 

[Herbiev]

Thanks John. I bought a stick of silver solder today from the local steel supply store. 45% about two foot long 1/16" dia for $13. Not sure if it has cadmium or any other nasties but I'll be soldering in a well ventilated area as I already have crook lungs ( COPD). Will let you all know how it turns out. And if it's not too messy, even a pic.

 

[deverett]

Thanks John. I bought a stick of silver solder today from the local steel supply store. 45% about two foot long 1/16" dia for $13. Not sure if it has cadmium or any other nasties but I'll be soldering in a well ventilated area as I already have crook lungs ( COPD). Will let you all know how it turns out. And if it's not too messy, even a pic.

To help stop the spread of solder where it isn't wanted, rub the area immediately outside the joint with an ordinary lead pencil (before soldering!) The old solvent Tippex used to work, but don't know about the new water based stuff.

Dave
The Emerald Isle

 

[Herbiev]

Thanks Dave. I'll try that.

 

[tornitore45]

Initially I bought 4 coated rods 1/16", paid dearly and used to much on every joint.
1/16" is too big for the small stuff in model work.
I bought one ounce of 1/32" wire for about $50, it is easy to measure the delivery and it can be formed in rings to be placed between when appropriate. It will be a long while before I need to reorder. Yes, the joint forms an inter-metallic boundary with a higher melting point which is good for multiple brazing.