Soldering rings

[Faith]

Hello!
So I've been making rings, first in random tiny sizes from scrap and then the right size (or not). Every time I hadn't been able to et the solder join on the first try. I had filed, spring fit the join, sawed though it, fluxed around the join and hard soldered and every time after pickling the ring split open on the mandrel. Then (for practice) I refiled where they split, sawed again and soldered and each second attempt was perfect (and too small).

So, in desperation I made some more rings and after filing and bending, fluxed around the join and heated the whole ring to soldering temp, then pickled, sawed through the join and (for good measure) popped open the spring fit sideways and painted flux on the cut faces as well as around the join, then popped it back in and soldered. Using that sequence I got every solder join first time.

My question is does anyone have any advice as to why my joins weren't working first time before? I'm just looking to understand why my new slightly lengthier method works?

Many thanks
Faith

[Dennis]

Faith, I think the first time round they were hard and springy from bending. So when you reheated them for soldering the joint relaxed and parted a little. A slightly open joint can still fill with solder but be weak.

On the second occasion, the ring was annealed and less prone to spring open.

So you can anneal before soldering and aligning the ends, or if a ring is springy, hold it together with binding wire for soldering. Dennis.

[Faith]

Thanks Dennis,
So I forgot to say, on my first attempts I did anneal the wire before bending, but I suppose the bending itself work hardened it again? Whereas when I annealed the wire in shape it only took a tiny amount of manipulation to line up the joint again before soldering? So it's about annealing the wire in shape?
Many thanks
Faith

[metalsmith]

Two possibilities I can think of in addition to Dennis.

1) solder was dirty, possibly invisibly, from natural oils on your skin thro' handling.
2) pickling inhibits flow; solder might flow to the fresh cut faces, but only if its in direct contact with the fresh cut material, which isn't always the case if it's recut

[Dennis]

Thanks Dennis,
So I forgot to say, on my first attempts I did anneal the wire before bending, but I suppose the bending itself work hardened it again? Whereas when I annealed the wire in shape it only took a tiny amount of manipulation to line up the joint again before soldering? So it's about annealing the wire in shape?
Many thanks Faith

Yes, bending the shank into a circle will quickly harden it, whereas a small amount of aligning does not make much difference, particularly as the movement is mainly side to side. you could think of the wire as having a memory and annealing making it forgetful. Dennis.

[Faith]

Thanks Dennis and Metalsmith (sorry I dont know your actual human name!), I'll watch out for all those points. Thanks for the analogy Dennis that makes a lot of sense :)
Faith