Cracks or swirls after sanding

[Phillipfiltz 1]

Hey guys, so I just started blade smithing maybe a month ago or so. On this piece I used 1095 annealed flat stock. I quenched in brine and everything seemed to go well. Then I sanded her down and bam I seen these swirls or cracks. Enlighten me guys, what do I have going on?

[Alan Longmire 2,714]

First off, welcome aboard!

 

Now the bad news... What you have there is classic case of quench cracks.  Despite what the description says, 1095 in thin blade form should never be quenched in water or brine.  It's just too harsh a quench.  Thick 1095 stuff works okay, but thin blades will almost always crack on you.  On your next one try using hot (hot enough you don't want to keep your finger in it) canola oil or mineral oil.  That'll be a fast enough quench to fully harden the 1095 without cracking it.  

 

1095 is picky.  It has to be quenched fast to harden, but the line between fast enough and too fast is pretty fine.  That's why you'll see people talking about Parks 50 (now made by Heatbath), Houghto-Quench K, Brownell's Tough-Quench, and so on.  These are fast oils that do the initial quench from 1425 to 900 degrees as fast as water, but then really slow the curve down to prevent cracks.  The trouble with it is it's expensive.  Personally, I find hot canola is good enough, and it's cheaper and smells better, too.  

 

Don't worry about it, we've all done it more than once. It's just part of the fun. 

[vlegski 4]

Yep, had to leave forge and  didn't want to leave a hot piece of 5160 laying around. Without thinking I buried it the water bucket. More snaps and pops that a bowl of rice crispies. In the future,, A quick online check will tell you which oils to use for specific metals.  Good luck in your endeavors with blades. 

[Phillipfiltz 1]

Thanks guys!! I really appreciate it! I’m assuming there isn’t anything I can do with the blade I made? 

[vlegski 4]

I'm not going to tell you it safe to use. I see two ways to go. 1. Make it a wall hanger. A reminder of what not to do.  2. Test it. With some protective gear on. Break or try to. If it breaks then look at why. Poor grain structure or dark stains at the break. I realize u are just starting out and its hard to destroy a blade you've  spend hours one. But, it can be a learning tool. I've done a lot of test blades. Some because I didn't feel comfortable with my process. Some deliberate. But I'd rather break one in the shop rather than have it fail when I needed it.

[Phillipfiltz 1]

Thank you! I think I will hang it up as a reminder of what to look for on my next blade. You guys and this forum is amazing

[Jerrod Miller 443]

On 11/28/2020 at 6:06 PM, vlegski said:

I realize u are just starting out and its hard to destroy a blade you've  spend hours one. But, it can be a learning tool.

Solid advice from vlegski.  If you aren't breaking any blades (on purpose) then you aren't taking quality control as seriously as you probably should.  And they don't have to be fully finished blades, just something with a pretty similar cross-section and heat treatment.  You need to find out if you have your heat treat dialed in.