Check out www.sandersonsteel.com/grades.htm
I took a quick look and it looks like you have exactly what you need to make an axle. You don't want something too soft or it will bend and you don't want something too hard or it could shear. I made quite a few axles back in the 70's when I worked in a custom bike fab shop but never paid much attention to what the axle stock was. I was young and the old farts just said Use This Stuff. Good luck.