Are you sure that you're not having a bad bar of mat'l to start with ? The reason I bring this up because I ran into this situation atlease 4 times in the past 3 years. These were waspalloy and 17-4. You can tell by looking at the finish between the splits pieces( use micro scope if possible) if they are dark then this could be the problem. Another way to verify is sending the mat'l out for X-ray.