Best Material for Marine Exposure + High Strength
Best Material for Marine Exposure + High Strength
(OP)
I am looking to find a stainless steel that is suitable to marine environments, and has a yield strength as high as possible. I am hoping to find something with a yield strength of ~170ksi, if possible. The material will be used in a structural part that will be stressed axially.
I have been researching 17-4PH, but stress corrosion cracking and hydrogen embrittlement seem to be possible problems. Is there anything available with similar properties as the 17-4, but without the associated corrosion issues? Heat treating 17-4 to H1025 seems to improve resistance to stress corrosion cracking, but I am not sure about the hydrogen embrittlement.
I have been researching 17-4PH, but stress corrosion cracking and hydrogen embrittlement seem to be possible problems. Is there anything available with similar properties as the 17-4, but without the associated corrosion issues? Heat treating 17-4 to H1025 seems to improve resistance to stress corrosion cracking, but I am not sure about the hydrogen embrittlement.





RE: Best Material for Marine Exposure + High Strength
RE: Best Material for Marine Exposure + High Strength
RE: Best Material for Marine Exposure + High Strength
We ran 17-4PH, 718, K-500, SCF23, Nitronic 50 and 625. All of them had UTS in the range of 160-240ksi. The first three alloy age harden, the last three were cold worked.
The 17-4PH and 718 showed loss of strength in the corrosive environment. The other alloys showed no loss of properties.
You just got $10,000 worth of test data.
If it were my selection I would look at K-500, 625 or SCF23 (or AL-6XN).
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RE: Best Material for Marine Exposure + High Strength
RE: Best Material for Marine Exposure + High Strength
You are calling for a very high strength material that is going to require something more exotic than the normal PH alloys.
[b]EdStainless[/],
If the environment isn't sea water immersion what do you think of Carpenter 465?
RE: Best Material for Marine Exposure + High Strength
Steve Jones
Materials & Corrosion Engineer
http://www.pdo.co.om/pdo/
RE: Best Material for Marine Exposure + High Strength
You cannot have the strength you want and have immunity to SCC and/or hydrogen embrittlment. No stainless steel with the desired strength, PH-type or martensitic, will have enough corrosion resistance to avoid the risk of SCC.
The best stainless would be the strongest which can not experience SCC and that would be 2205. 2205 will not experience pitting but may see some crevice corrosion. In that case 2507 is needed. You would then have to settle for yield strengths in the 70ksi range with these duplex alloys. Still pretty good compared to austenitics.
Michael McGuire
http://stainlesssteelforengineers.blogspot.com/
RE: Best Material for Marine Exposure + High Strength
Regards,
Cory
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RE: Best Material for Marine Exposure + High Strength
1) type of item or element you're talking about
2) marine environemnts means seawater immersion?
Strider
http://www.corrosionist.com
RE: Best Material for Marine Exposure + High Strength
The solution was sat. NaCl (26%), 300F, CO2 sat (pH2-3).
For materials over 160ksi UTS the ones that showed no reduction in strength or elongation were:
K-500 (CW + age)
6%Mo Superaustenitics (CW)
625 (CW)
I presume that you could use 725 and CW+age, but you may not need it. We used 625 cold worked at 185ksi UTS.
Custom 465 may work well for this. It has pretty good corrosion resistance and the strength level would be easy.
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Rust never sleeps
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RE: Best Material for Marine Exposure + High Strength
The parts are going to be load cells and links. They will not be immersed in seawater (during normal use at least), but are used on offshore platforms and other such environments.
Custom 465 has the high strength and resistance to stress corrosion cracking, but I haven't been able to find any info on hydrogen embrittlement. Is that an issue with this material?
RE: Best Material for Marine Exposure + High Strength
If it helps any it is considered a drop-in replacement for plated 4330M and 4340M plated parts for airframe components.
It is being used more and more high strength fasteners with no mention of H2 problems as you normally see with high strength fasteners.
RE: Best Material for Marine Exposure + High Strength
= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection
http://www.trent-tube.com/contact/Tech_Assist.cfm
RE: Best Material for Marine Exposure + High Strength
17-4 has better corrosionn resistance, but not good enough for marine environment.
Michael McGuire
http://stainlesssteelforengineers.blogspot.com/
RE: Best Material for Marine Exposure + High Strength
I'll have to disagree with your post concerning both materials, 17/4 and C465. Both are used in and around marine environments though at present 17/4 has a longer exposure time than C465. 17/4 has been used for boat shafts for years. C465 has been use both for boat shafts and fasteners for marine service. There is also a lot of marine hardware made from 17/4.
I've read in Carpenter literature that C465 has received certification for arresting gear components for Naval Aircraft, which should make it essentially corrosion free and free from SCC in marine environments.
RE: Best Material for Marine Exposure + High Strength
Michael McGuire
http://stainlesssteelforengineers.blogspot.com/
RE: Best Material for Marine Exposure + High Strength
Be advised that if component is going to be used in pressure containing part or vessel, ASME code limit use of duplex to less than 600F.
RE: Best Material for Marine Exposure + High Strength
But are you sure that for your service, you said normally not in contact with sea water, you need a SS?
regards
Strider
http://www.corrosionist.com
RE: Best Material for Marine Exposure + High Strength
From your first post, what is SCF23, or where would one obtain it? Thanks.