Inconel X-750 for Seawater Applications Springs 1

[stanier]

Would the experienced material engineers and scientists of this forum please comment on the statement below:

Inconel X-750 springs - UNS N07750 (similar to Inconel 600) has no molybdenum and as such has low resistance to crevice corrosion in seawater or brine. The high velocity of seawater which seems to be associated with the springs in the non return valves will provide the optimum opportunity for this material to succeed but as a general statement this
material could not be recommended for these environments.

Geoffrey D Stone FIMechE C.Eng;FIEAust CP Eng

http://www.waterhammer.bigblog.com.au

 

[SJones]

For ambient temperature, deaerated seawater, in the absence of H2S, the statement would be reasonable; however, one does need to look at the specific geometries and also the other materials in contact with X-750.

Steve Jones
Materials & Corrosion Engineer

http://www.pdo.co.om/pdoweb/

 

[TVP]

I agree with SJones that the characterization is reasonable. High stress applications (springs, fasteners, etc.) for seawater environments typically require more corrosion-resistant grades like 686, 725, etc.

 

[EdStainless]

If the reat of the structure is providing some galvanic protection then you may be OK.. Look at higher alloy grades if you need it better, they still make Elgiloy.

 

[strider6]

Stanier

I agree with the previous comments. Also in my opinion it should be clearly stated which is the service, brine or seawater, chlorides contents and temperature to give a indication for a material.
I think that this paper can give you some good advise on mat sel for spring in seawater.

High Strength Corrosion Resistant Superalloy Fasteners, Springs, and Hardware for Marine Service

http://www.specialmetals.com/docume...t Superalloy Fasteners Springs & Hardware.pdf

regards

S

http://www.corrosionist.com