I haven't had anything fail like that so not totally sure. But I would say the steel has either not been hot enough, it's been contaminated or flux hasn't done it's magic. The brass will flow out and create what's essentially a mechanical bond between brass and steel. And that hasn't happened here. The brass has sat "loosely" around the steel. This happens if the brass has been melted before it bonds with the steel rather than the steel being hot enough for the brass to flow out on the steel.
This happens a lot when you first learn how to soft solder for example. You heat the solder rather than the bits you are trying to join.
Yeah gotcha. I thought initially you meant that the type of joint is wrong.
I definitely understand what you mean about heat. The filler has come off the tube rather than cracking so definitely not bonded correctly.
I haven't had anything fail like that so not totally sure. But I would say the steel has either not been hot enough, it's been contaminated or flux hasn't done it's magic. The brass will flow out and create what's essentially a mechanical bond between brass and steel. And that hasn't happened here. The brass has sat "loosely" around the steel. This happens if the brass has been melted before it bonds with the steel rather than the steel being hot enough for the brass to flow out on the steel.
This happens a lot when you first learn how to soft solder for example. You heat the solder rather than the bits you are trying to join.
Does it make sense what I am saying?