Originally Posted by
Kuromori
I believe Reynolds can still cold draw tubes to diameter and gauge, not just butt them.
Possibly, but I think that involves quite a bit more equipment. I've seen the butting machine on YouTube and it's not much bigger than a large lathe or something like that. Then because they're heat treating (725 and 853) after cutting and butting they don't need a huge oven.
You may enjoy this video:
Although they don't show the heat treatment (and those tubes they're making are 853).
Originally Posted by
Kuromori
Regarding 853 however, Reynolds notes that 853 work hardens particularly easily and broke their drawing machines multiple times, thus requiring "repeated annealing (softening) after each stage" of drawing. This would be in line with Reynolds recommendations of not manipulating 853 much beyond cold setting, and makes it likely 631 tubes are annealed some point soon before leaving the factory.
I think they just butt the 631 and then heat treat if afterwards if necessary for 853.
I have no idea where they get the 631 from though... Presumably they go to a steel mill and ask them to melt up an entire batch of their specified alloy, and maybe those guys do the inital cold drawing in the same facility.