Any heat treat suggestions for max. strength levels and hardness with good impact properties. Section size approx. 8inch round. Part shall be subject to high velocity impact.
12756;
There is not enough information in your post to provide any specific help. What are the actual service conditions, service temperature, type of high velocity impact conditions (fluid or solid particles) against the 4330V steel? Why did you even pick this steel?
What are your minimum strength requirements for this application - min UTS and YS? Get the answers to the questions above sorted out, and we can help you.
The hardness relates to the tensile strength, and at 165 ksi the hardness will be ~ 340 HB or ~ 36-37 HRC. This grade would be tempered at ~ 600 C to achieve that hardness. The Latrobe datasheet shows hardness vs. tempering temperature. Ignore my ASM reply with regards to tempering temperature, since I assumed the more typical hardness range of 47-50 HRC.
12756;
No. This material behaves similar to 4340, and is immune to temper embrittlement. The article below is an excerpt from
the Aerospace Structural Handbook, FeUH Ferrous Alloys. This is a very informative article on this material, worth reading.
Google
https:/.../Applications/ASMDDEMO/App/PDF/Ultra%20High%20Strength%20And%20Age%20Hardening%20Steels/1204.pdf