ST 52 / 34CrNiMo6 thruster shaft

[iceland1]

HI, does anyone have experience of using ST 52 or 34CrNiMo6 for marine thruster shafts? which is best?

 

[gieter]

I suppose it all depends on the strength you want. St52 has a tensile strength of 490-630MPa, a Yield of min.335MPa and an Elongation of min.20% (depending on thickness).
For 34CrNiMo6 this is 1000-1200MPa, min.800MPa and min.10% resp.
Welding 34CrNiMo6 is a problem. Being low alloyed and having about 0.34%C, it can't be welded without the propper precautions.