S-phase nitride coating on steel(S-143)

[ivoryhorseman]

Hi All,

I had recently performed S-phase nitride coating on S-143 precipation hardened steel to improve cavitation erosion properties of the material. however the the cavitation erosion property worsened after the s-phase nitride coating was performed, instead of improving it.

I am confused as to why this has taken place since, S-phase nitriding should provide more strength to the surface rather than ordinary S-143 ppt hardened steel. does cavitation erosion has to do with anything with surface finish and not the strength etc.


Can sombody give a an explanation on what could have possibly gone wrong.

is polyurethane coating a good way to prevent cavitation erosion.

 

[cloa]

What is the full situation, fluid, temperature etc.?

http://www.eng-tips.com/threadminder.cfm?pid=1529

Use translation assistance for Engineers forum

Note the rules include No Student posting

 

[ivoryhorseman]

The Temperature at which the nitriding was perfomed was at 420°C. the s-phase S-143 sample and the S-143 sample were mounted on a large impeller. after a thousands of hrs of testing the mass of the coupons were measured and found that the S-phase S-143 cavitated more than the ordinary s-143 coupon.

I will have to get back to the nitriding people to understand the extact treatment conditions etc, since the S-phase nitriding was performed by a third party.

however we were promised a hardness 3 times that of ordinary S-143 coupon. Which didnot happen at all.