Manufacturing Process Help 1

[zl93]

Hello All

If CMV pipework has been made via metal turning as part of its manufacturing process will it have any negative affect on the materials performance? Will there be any degree of cold working and change in microstructure?

Any feedback would be beneficial

Thanks

 

[metengr]

What is CMV?

 

[zl93]

It's a type of creep resistant steel with alloying elements Chromium (Cr) and molybdenum (Mo)vanadium (V) giving it's name cmv , it's used in high temperatures and pressures situations such as mainstream pipework in power stations.

 

[AndrewFinAustralia]

Under service conditions, does it experience cyclic loading (hot/cold or flexing)

 

[metengr]

Here in the USA, this material is CrMoV and is used in turbine components like inlet piping, shells and steam chests. In most cases, the material is in the form of castings because of the large components.

Regarding piping, I see no problems with boring from a large round. Forged and bored pipe, for example, is supplied as special order.

 

[UconnMaterials]

Zl93,

Metal turning or spinning can either be a cold working process or hot/warm working process. I've seen this process performed on sheet metal in cold working processes. For plate stock, this will most certainly need to be a warm/hot working process. Needless to say the final material will be in a different condition than the stock material. What final condition are you targeting and what process are you using so I can be of more help to you.

Uconnmaterials

 

[metengr]

zl93;
You can also review ASTM A 356 material specification "Standard Specification for
Steel Castings, Carbon, Low Alloy, and Stainless Steel, Heavy-Walled for Steam Turbines" regarding Cr-Mo-V casting grades and heat treatment. If you are machining pipe as you stated in your post, it would appear you would be using a large solid round or forging versus rolled and welded plate to produce pipe.

You may need to perform a stress relief treatment after heavy machining, using the requirements in A 356.