Quote from Ed Caffrey on September 20, 2022, 6:24 am

This is a REALLY good thing to bring up!  Just so everyone else knows, Vic sent me some text messages, and to fill in some blanks....  what Vic is finding are small black lines running with what would be the length of the steel he started out with.  The steel itself is 5160.

What is happening to here, is what made me stop using 5160, ans switch to 80CRV2.  What is it?  It's the result of industry, in this case the steel industry, eliminating jobs to increase their bottom line.  The jobs they eliminated were known as "scrubbers".  These where people who worked, scrubbing the rollers clean as steel was being rolled to size in the steel mills.   When the steel industry eliminated them, the scale and/or slag that builds up on the rollers either gets into the steel, or causes some tiny "cold shuts" that manifest themselves as tiny inclusions or cold shuts, that typically don't show up until the finish grinding, or more often when a person is hand sanding/finishing a blade.  Then you find what might look like a fine hair....but as you sand it grows larger and larger.   SOMETIMES..... you can sand it out, but in my experience that is a rare thing.      

  What's the answer/solution?  This occurred so many times, it finally forced me to stop using 5160, and replace it in my shop with 80CRV2.   For me it was a blessing in disguise.... I refer to 80CRV2 as "5160 on steroids".  For those who haven't tried/used it, 80CRV2 is an outstanding steel.  Easy to forge, and very simple to heat treat.  And the best part from my perspective.... I can grind 80CRV2 to an almost zero bevel edge, and it does not chip, nor bend.  It flexes and bounces back.    If you use 5160, and haven't run into this issue, then you've dodge the bullet.  But sooner or later I suspect you will encounter it.   😉