Erik is right. And I wonder how many bicycle part fillers are in any 4340 purchased from China.

I require material certs on all critical machinery components at work; why settle for less on our own stuff? No need to answer, but the point is you would be amazed at what variations in quality you can get in materials. 4340 is definitely on that list as well.

What you want to know in general is;

1) Composition ranges and tolerances
2) Processing methods and temperatures
3) Inspection procedure for detecting flaw size and tolerances
4) Stress strain curve (tensile test) on material drop

That's part of why real racing cranks cost real $ ................

Kitz