What did I do?

L

lilharv19911

Joined
Oct 20, 2016
Messages
8
This is my first knife. As you can probably tell. So Imay using a mystery steel from my local Farm Supply store that I had laying around. I figured why use the good stuff on my first knife. Just in case I had to abort the Mission.

So I watch a few videos from credible bladesmiths and a saw that I could use a torch. So that's what I did since that's what I got. I heated it and checked with an old speaker magnet and did my quench. All good so I thought. After sanding off the layer of crud I see this. I have a few days of sanding to do to fix this problem. What did I do wrong? It's only on one side and I ran the torch on both. I've been working on this knife for 2 weeks (every night from 9pm-11pm after my kids are asleep) I don't want to give up on it. Any tips to fix it? Sorry if I posted this in the wrong place. I tried to do a search. Couldn't find anything helpful. Thank you

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Unless the steel has enough carbon to harden, it will never make a working knife. It sounds like you used mild steel which is low carbon and can't be successfully heat treated. See the stickies at the top of this page.
 
It's just a mild steel man its not knife metal. So you really cant heat treat it. I did the same thing just for cheap practice grinding but honestly it's not worth it. You practice get decent and grinds then that's it you can't do anything else. Check out alpha knife supply chuck is awesome. They have a $25 minimum purchase but honestly you can get quite a bit of steel for that much money. From one rookie to another I hope this helps.
 
Thanks guys. I appreciate the info. I will try again with the right stuff this time. Also I see the stickies now. I will utilize them more often.

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What you are seeing is scale. It has to be ground off to get to the hard ( in this case, not very hard) steel. It can be soaked overnight in a solution of sodium bisulfate ( Ph down from a pool supply) and that will remove some of it, then sanded/ground.
 
Regardless of the type of steel you will have scale form. It is almost unavoidable when heat treating (espcially in open air with a torch) without some sort of anti scale compound. You just have to grind this layer off after heat treat and it will go away.
 
BKT said:
Regardless of the type of steel you will have scale form. It is almost unavoidable when heat treating (espcially in open air with a torch) without some sort of anti scale compound. You just have to grind this layer off after heat treat and it will go away.
Click to expand...
I sanded 50g then 150g then heat treated. I figured I wanted to get all the deep tool marks out before hardening. Should I wait to sand till after HT?
 
Stacy E. Apelt - Bladesmith said:
What you are seeing is scale. It has to be ground off to get to the hard ( in this case, not very hard) steel. It can be soaked overnight in a solution of sodium bisulfate ( Ph down from a pool supply) and that will remove some of it, then sanded/ground.
Click to expand...
I'm going to try soaking it tomorrow night and see where that gets me. Thank you

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No. You want to sand before heat treat AND after. If you don't sand before, you will have a hard time getting the scratches off after, especially the deep ones when sanding by hand. I would go to 220 prior to heat treat, that's just me. I feel it is easier to get the scale off of a smoother surface post HT. After heat treat, you need to sand off the scale, but you shouldn't have additional scratches to worry about.
 
lilharv19911 said:
I sanded 50g then 150g then heat treated. I figured I wanted to get all the deep tool marks out before hardening. Should I wait to sand till after HT?
Click to expand...

Two schools of thought. Some people sand prior. Personally I take it to around 220 on the grinder and then quench. I am going back to the belts anyways after HT to clean them up so I am not going to spend a whole lot of time getting the finish perfect prior to HT. The steel is softer so its easier to do prior to HT, but it always seemed like a waste of time to me after you quench and that nice finish is ruined. I just never noticed any time saving by finishing out pre HT.
 
Thanks for all the pointers! It's much appreciated. I will be ordering actuall knife steel soon and see what I can do

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