Why do my axle shafts look like this?

[PirataCoqui]

First time ever looking at axle shafts so this could be pure ignorance, but why do my axle shafts look like a zebra?

This normal?

Pretty sure these are stock and know nothing else about them.

Dismantled to do a big brake kit and came across bad ball joints.

 

[D's Jeep Wrld]

It's normal. My original Dana 44&Dana 30 shafts out of my Lj looked the same,And same with the others I've broken!
Edit- Why are they like that? I dunno,Out of curiosity I'd like to know why they come out like that

 

[CMBD]

That spiral pattern is from heat treating.