Quote:
Originally Posted by steelslaver
Yes that is some huge grain structure. Should not look like that at all. Something went wrong i the process somewhere.
Before the MIM haters start in, think about this.
I purchased 6 2'x3' pieces of high grade German D2 tool steel 3/16" thick. This was rolled sheet so it had been "forged" repeatedly in the process from taking it from a billet to sheet. I had 2 sheets of it water jet cut to a pattern I use to make my standard hunting knife. On one of the blades after grinding the bevels and working to 400 grit sanding there was a small line that would not sand out. I took it back to the belt sander and it still remained after hitting that area again. Put it in a vise and applied side pressure. Snap and at the break an inclusion was visible. Forged is not immune to failure either. This was a steel that was poured into a billet from an inert atmosphere, induction oven, before being hit with the hammers and rollers to reduce it. Top shelf processes by people who pride themselves in their abilities.
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Any one with a nominal gear head background will be able to regurgitate stories about failed cranks and rods that were forged. Anything man made can fail - forged, MIM, billet or cast - it doesn't matter. It's too bad records haven't been kept but I'd bet that MIM part failure and forged part failure numbers would be pretty close to being even.