How to confirm if a shaft material is actually forged shaft?

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Signs That a Shaft is Forged

Hello,

I am buying a forged shaft material from a vendor to manufacture a pump shaft on lathe. My question is: how can I confirm if it is actually a forged material and not a bar? Is there a texture I can feel or anything visibly I can see to confirm if it is actually forged material? Is there a test to confirm that?

Material is:
415 SST material
5 inch OD x 100 inches long

Basics of Forged Shafts

Forging is done to produce a near net shape so the shaft wouldn't be a straight diameter along its length. Bar stock that is a straight diameter can be provided as cast but is most likely wrought or extruded which are similar to forging. What is the importance of forging to you? If it matters, why don't you have a material spec from the manufacturer?

Is It a High-Power Shaft?

Is this a large, complicated, high horsepower shaft? But beyond that, if they machined it from bar how do you think that they made the bar? It would have been forged. It may have been hot extruded, rolled (hot and/or cold), and/or forged (hot and/or cold), but the result is the same. It was reduced from the original cast size. And that is what matters. Along with chemistry and HT there isn't anything else. The only methods are destructive.

Importance of Grain Flow

I second what Ed said, however I will add the reason also to forge is to obtain grain flow as required by the end item manufacturer (customer). Have them run a test sample with the grain flow direction.

Get Material Certification

If you bought your raw material to a recognized forging specification, it’d be a forging. Regards, Mike. The problem with sloppy work is that the supply FAR EXCEEDS the demand

Standards and Specifications

ASTM A182/A182M-21. Standard Specification for Forged or Rolled Alloy and Stainless Steel Pipe Flanges, Forged Fittings, and Valves and Parts for High-Temperature Service. 415 is 13-4 martensitic stainless steel, so I doubt it makes much difference, since heat treating defines the final properties while obliterating any grain flow effects. 13-4 never has a problem meeting minimum tensile properties, and it has the fairly unique characteristic of being fully hardenable to essentially unlimited thickness. From a quality perspective, I think you need to be more concerned about the ultimate source (i.e., geographic) of the steel, but the same applies to all metals.

Testing for Grain Flow

Sorry, brother, grain flow does not change from heat treat. Only by means of mechanical forging. Worked with many forging parts for aircraft applications. We had to certify grain flow to our customers. Forgings have a higher torsional strength rating. Used in shafts, gear shafts, gears in general.

Advise from a Metallurgist

What if you order two of them and send one for testing? A lab can check grains under a microscope and subject it to a tensile test or whatever other tests you need to certify. If you don't trust the material certs or certifications the material supplier is issuing, then that is the only way of checking. We sent a valve for metallurgical analysis once because it failed in a very strange and creative way, and the metallurgist was able to tell us exactly what the casting was made from and that the cast body was defective because the manufacturer didn't control the rate of cooling properly when they did the casting. They can be very helpful sometimes.

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Re-Heat Treating Effects

Unless it is because of the intergranular trash that leaves indications. I can re-heat treat a PH SS a number of times, making the grains equiaxed and reducing the grain size each time. The toughness goes up a lot, and the strength drops a very small amount. The same thing happens with many alloys, depends on the hardening mechanism.

A General Approach

Were any of those parts martensitic stainless steel? It's a daily problem I have working in a large organization that civilian engineers project issues from one alloy onto all other alloys. For example, they worry about the heat-affected zone properties in a 304 weld. The OP is looking for a reason to start a science project, when it would be less trouble to just buy the next more expensive alloy and sleep well at night.

Supplier Recommendations

Hello All,

Thanks for your comments. They are all very helpful.

Can you name a supplier that can supply this forged material in above mentioned size (in the US)? I will get a quote on it.

Your piece is large enough you may be able to order direct from the source. Here is one link for reference:

https://www.outokumpu.com/en/products/stainless-steel-bar

Final Words

If this is a commercial piece, ensure it must be NADCAP approved. That narrows it down. Get three suppliers to quote and pass on the cost to your customer. The first two that I think of are Howco and Scot.

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