2nd attempt at San Mai

[Ken H>]

OK, this is my 2nd attempt at San Mai, this time using .138" thick 1095 for center core. I put a .120" side of 416 on one side, and just to see what AEB-L would do I used .062" thick on other side. This to give SS clad 1095. From what I can see the AEB-L didn't work so good, it's the side with all the cracks. Take a look below - what caused the cracks? What the temp too high? OR - perhaps AEB-L just isn't good for San Mai?

The above billet is after cutting 1/4" or so from each edge and leaving what is seen. I'm pretty sure that is the AEB-L in .062" material. Total size is around 1" wide X 3" long after trimming and grinding. There were big cracks around the edges which were cut away.

This below is the other side with .120" thick 416 SS. This side looks good. What is the narrow shiny line just below the line of 416? What I see is the cladding of 416SS, then a thin line of black, then the shiny line, then rest is the black oxide on 1095.

Any ideas why the line is there? Why the other side cracked so much?

Another point, after all the forging and grinding it looks like the 416SS thinned down a good bit, but the 1095 core doesn't seem to have thinned out much at all. Is this normal? I was expecting the center core to thin out as well as the outside SS. If I'm wanting a final blade thickness of around .140" or so, what would be a good thickness core to use? I've got .040" thick 410SS but that seems too thin for cladding. comments?

Thank you all for comments and guidance.

 

[lanternnate]

I tried San mai with aeb-l once, and I also had cracking issues. Mine were a little less pronounced. They didn’t show up until I etched and they were many micro cracks. The feedback I got at the time was that I overheated the aeb-l during the forge welding. It seems to be sensitive to overheating. If I tried stainless San mai again I probably wouldn’t try aeb-l again. It’s tempting because it’s the right size at the right price, but it doesn’t seem to play nice.

 

[coldsteelburns]

The shiny layer at the lamination would be the now carbon-deprived 1095 (iron) and the black line is the (now) carbon-rich stainless. It migrated from the carbon-rich 1095 to the carbon-lacking stainless at the high forge welding temps probably a few thousandths or so on each side which is mated up against the other. Ask Karl as he has plenty of neat examples that he's photographed of his san mai knives.


~Paul
My Youtube Channel
... (Just some older videos of some older knives I've made in the past)

 

[Ken H>]

The feedback I got at the time was that I overheated the aeb-l during the forge welding. It seems to be sensitive to overheating.

I sorta thought it might be overheating but didn't know for sure. I guess that tells me I've got plenty of heat {g}. My next billet might be with 416SS on both sides with 1095 in the center.

Any comments on the center core not thinning the way the outer layer did? I'd like to get the center core to thin out some also. Could I draw it out removing the edges where I stick welded and perhaps the outer edge didn't forge weld good. Then drawing out the billet by hammering sides, then edges at regular forging temps rather than full welding temps?

Thanks Paul, I wasn't sure what that line was. It's neat and I like the line.

Thanks for the info.
Ken H>

 

[Ken H>]

The shiny layer at the lamination would be the now carbon-deprived 1095 (iron) and the black line is the (now) carbon-rich stainless. It migrated from the carbon-rich 1095 to the carbon-lacking stainless at the high forge welding temps probably a few thousandths or so on each side which is mated up against the other. Ask Karl as he has plenty of neat examples that he's photographed of his san mai knives. ~Paul

Paul, thanks for such a good explanation. That makes sense because the line shown is only on the side with 416 which has .15% carbon, while the other side with AEB-L with .67% carbon doesn't show the line