W2 with a hamon showing strange marks

[Willie71]

Thank you Don!



Very interesting article stezann, thank you. It explains a lot more of how grit interacts with the surface at a level we cannot see. Had to read it twice and then bookmarked so I can go back.

I’m pretty sure this is what Kevin was explaining to me.

thanks for the article.

 

[Josh Rider]

That’s really interesting. I wonder if it happens to any etched steel. Surprised it doesn’t get mentioned much in Damascus. Or maybe it’s just harder to spot.

 

[Barry Clodfelter]

I imagine it is hard to see in Damascus. I have only a handful of knives with a hamon this was the first W2 the rest were 1095 and this was the first time I have seen those ghost scratches. I have another blade forged from the same bar of W2 and HT at the same time as this one. It is at a clean 800 now so hopefully there will be none on this one. If so I will have several 4' bars of W2 for sale....

 

[Tenebr0s]

I remember Larrin's article on cold forging saying that work-hardened steel austenitizes more easily. So if the bottom of 40 grit scratches are work hardened, even after the scratches themselves are removed, it's possible that the work-hardened streaks responded differently in the quench than the surrounding steel, possibly forming some martensite and thus standing out when etched?

 

[Don Hanson III]

It happens from grinding after heat treating, and only above a hamon in the soft steel. The scratch is gone, but show up as dark grinding scratches after etching.

If you grind closer to finish thickness before heat treating, then use gator belts no coarse than A160 to finish it pretty much eliminates the ghost scratchs.

 

[Chris Lyons]

Have you tried the ol' frosty lemon juice hamon polish? Just a thought. Might be able to pull some of the hamon details out without the 'ghosting' in there, since the lemon juice tends to do a more subtle etching than the FC does..

 

[Josh Rider]

I forged this out of some old w2 I had lying around and got those marks in several spots. Only visible with a dark etch.
When I polished it, it disappeared.

 

[milkbaby]

Nice knife!
I also think those ghost scratches might be caused by work hardening or otherwise damage/modification of the underneath steel's crystal structure due to low grit grinding in the early shaping steps. Those are features i believe can pop up through etching.
There you find an interesting view on a micro scale of this behaviour:
https://scienceofsharp.com/page/2/

Thanks for posting that! mind = blown!