I spent most of a year once trying to find a materials solution to a specific cavatition problem in the throat of a jet pump. We tried 15 different materials and were able to vary the time to failure between 20 minutes and 2 hours. The U.S. Navy did the groundbreaking work on cavitation in the 1950's to lower the sound radiation of submarine propellers. That work found a bunch of fluid-mechanics ways to avoid or delay cavitation, but didn't find any materials that were resistant to damage from the cavitation that occurred. Wish I had read that before I wasted so much time and money.
I would expect that any difference in the time to failure of the two materials you mention would be on the order of hours rather than days.
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I agree with zdas04. But since you are posting in this forum, it might perhaps be possiblefor you to search for ways to avoid cavitation by presenting the pipeline (and valve ?) lay-out with complete flow info? New thread?