forging minimum thickness limit

[bluebonnet921]

Hello,

Is there a minimum thickness limit for forging of apart that is less than 2-inch thickness? if yes, why is that.

thanks

 

[btrueblood]

What kind of forging, on what kind of material?

 

[bluebonnet921]

Hello btrueblood,

Super duplex SS. Forging into a valve body.

thanks

 

[EdStainless]

Are you asking about the tolerances? Is it specified as a 2" dimension?

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P.E. Metallurgy, Plymouth Tube

 

[bluebonnet921]

What i'm asking about is will forging a body with wall thickness less than 2 inches be acceptable or in this case casting is better? if forging less than 2 inches is not recommended, then why is that?

thanks

 

[EdStainless]

It will have more to do with the range of walls, from min to max section.
And what tolerances you are looking for.

Remember that the heat treatment on these alloys is very critical.

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P.E. Metallurgy, Plymouth Tube

 

[dgallup]

I've had forged parts where the maximum dimension was less than 2 inches.

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[djhurayt]

I'm a little lost. Like dgallup says lots of forged parts are way less than 2 inches.
pistons
con rods
hammers

Are we sure we aren't talking about 2mm. Certainly I'm no forging expert but I could see that being tough to control.

 

[tbuelna]

I assume you are talking about a closed die forging for this valve body. With hot forging (usually at around 1100-1250degC for duplex stainless material) you can produce fairly thin walls in small local areas. The min limit would depend on the section geometry (thickness, volume, transition profiles, fillet radii, etc) around the thin wall area. It may also require multiple (progressive) forging dies to get the final shape. If the metallurgy (grain size, etc) in the thin wall area of the forging can have less demanding requirements than the rest of the forging, it might lower part cost by reducing the vendor's scrap rate.

For a fatigue or fracture critical component it is common practice to use a forging that is 100% machined on all surfaces. Hot forgings would usually have at least 1/8" material removed from the as-forged surface. So if your final wall thickness is .25" after machining, the as-forged wall thickness would be .50" from the added 1/8" machine stock on both sides.

Castings are not typically used for fatigue or fracture critical applications. However, for applications where fatigue/reliability are less of a concern and cost is important, a casting will usually require less machining, produce less material waste, and allow details such as internal cavities.

 

[bluebonnet921]

Thank you tbuelna, this answers my question.