Tough Environment....
Tough Environment....
(OP)
I have a tough one here....
currently a modified 420ss (+1%Mo) (HRc~54) is failing relatively fast, we prototyped 302 Rolled to Spring temper; at 160F they lasted longer than the teh 420, at 212F they dont last long at all.
Environment: 212F, saturated steam, some fine particulates, tap water, condensate.
Application: Reed Valving. Compressor head, both intake and discharge.
Failure analysis results: 420mod is failing either through general corrosion or IGC, both have been observed on different failures. EDS shows a small Cl peak, along with other Ionics. Teh 302 is not failing through obvious corrosion, there is some red rust appearing on the surfaces, no IGC or general corrosion damage at the intiation location.
At this point I dont want to go to inconels or elgiloy, but I need a high strength spring material, current gague is 0.003" thick.
Any recommendations?
currently a modified 420ss (+1%Mo) (HRc~54) is failing relatively fast, we prototyped 302 Rolled to Spring temper; at 160F they lasted longer than the teh 420, at 212F they dont last long at all.
Environment: 212F, saturated steam, some fine particulates, tap water, condensate.
Application: Reed Valving. Compressor head, both intake and discharge.
Failure analysis results: 420mod is failing either through general corrosion or IGC, both have been observed on different failures. EDS shows a small Cl peak, along with other Ionics. Teh 302 is not failing through obvious corrosion, there is some red rust appearing on the surfaces, no IGC or general corrosion damage at the intiation location.
At this point I dont want to go to inconels or elgiloy, but I need a high strength spring material, current gague is 0.003" thick.
Any recommendations?
Nick
I love materials science!





RE: Tough Environment....
RE: Tough Environment....
a. Grade 11R51, which is a spring temper Type 301 that has some Mo added to it. My guts say that this will not be enough of an improvement, but my guts aren't that smart.
b. Grade SAF2205, which is a duplex (ferritic-austenitic) alloy that can be cold-rolled to a spring temper. It is not as strong as either 11R51 or the 420 grade you started with, but the tensile strength can be ~ 1500 MPa.
c. Grade SAF2507, which is another duplex grade with even better corrosion resistance than SAF2205. I think 2205 would be sufficient for corrosion resistance, but the "Spring" section of the Sandvik Strip website only shows 2507, which makes me think 2205 may not be available in sub 1-2 mm thickness range.
RE: Tough Environment....
israelkk- we dont passivate any of our SS product, either 420 (Hitachi or Sandvik Matl.) or the 302.
TVP - yeah, 11R51 was thought of, however I didn't think it was going to be substaintially better than 302, though the Mo might help. Thanks for the info on the duplex steel, I was unsure if the duplex steels were available in a spring temper.
RE: Tough Environment....
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RE: Tough Environment....
RE: Tough Environment....
IE: Mechanical fatigue accelerated as a result of the environment.
We visted the customer yesterday, at this point I think only exotics are going to solve the problem.
Thanks for the help.
nick