From what I could find, this material is supplied under a DIN Standard (1.7225), and is basically a Cr-Mo-V alloy steel. I am assuming that you are considering reverse engineering of this axle.
If so, you need to carefully investigate or determine the original specified mechanical properties of this steel before you can zero in on an equivalent material substitution.
Critical items to consider before you select a material;
1. Is this a thru-hardened axle? If so, what are the specified minimum mechanical properties (ultimate tensile strength, yield strength, percent elongation) for the load bearing axle?
2. Is there any surface hardening treatment of the original axle?
3. Toughness requirements for low temperature service?