On Mon, 5 Oct 2015 21:40:06 -0700 (PDT),
wrote:

What would be the heat treating process if i bend the 4130 25.4mm OD 3mm Thickness pipe at an angle of 45Deg, just for relieving stresses?

I believe that the standard stress relief for 4130, after welding, is
to hold the material at 650 degrees(C) for 1 hour per inch of
thickness.
--
cheers,

John B.