Laminated Blade Metallurgy

This is fascinating stuff - at least to me.  Here's what is going on in these laminated blades...  Kevin Cashen has done photomicrographs of the inside of one of these blades and it's cool stuff.  (This explanation only applies to blades with 400 series stainless sides welded directly to the center core)

1.  This dark layer is the virgin carbon steel at the core (usually 1095).

2.  This bright line, which looks like a separate layer is also 1095, or rather it used to be.  This area of the carbon steel core has literally been sucked dry of carbon - gobbled up by the carbon hungry, free chrome in the stainless.  This area is essentially pure iron now.

3.  This dark band is not 1095 again, this is 416 stainless, or rather it used to be.  This area of the 416 has "eaten" all that carbon from the core steel and the free chrome which used to provide stain resistance is now tied up as chromium carbides that are no longer stainless.

4.  This is the unaffected 416 stainless.

Pretty cool, huh?