Tempering???

[islandmike]

I have a rough knife i have tried to make.. It doesn't look to bad ,but i would like to know if i could temper it myself? I have been told I can do it with a toaster over..Is this possible?

 

[Stacy E. Apelt - Bladesmith]

Mike, You have to harden it before you temper it.The hardening is done at 1550 degrees,and requires at the minimum a torch,some sort of quenchant,and the knowledge of how to do a HT.Tempering is done at 350-400 degrees and can be done in the toaster oven.Read up on heat treating.Also you have to know what kind of steel you have.

 

[Rob!]

We've all had this thought and figured it was a pretty simple question. Unfortunately, it is rocket science.

A blade needs to be hardened first. That cannot be done in a toaster oven. After hardening it is so hard it is brittle - and needs to be 'tempered' (softened) back a bit. Often, this part can be done in a toaster oven.

To help you with specifics, we'll need to know what kind of steel you used. Congrats on making your knife. Hope we can help.

Rob!

 

[DAMNENG]

I have a rough knife i have tried to make.. It doesn't look to bad ,but i would like to know if i could temper it myself? I have been told I can do it with a toaster over..Is this possible?

The heat treating process used to harden steel, usually requires two steps (always exceptions!),

First the steel is heated into the austenitic range, ( usually 1450 to 2000°F)where the grain structure rearranges its self into austenite. Austenite is a solid soution of iron and carbon. Once this has been done and the appropriate soak time for the given steel has elapsed (this is a difussion process and is restricted by difussion rates), the steel is then quenched. This quenching if done within the alloted time to miss the pearlite nose, tje austenite is converted to martensite. This is hard as the steel will get. Martensite is brittle until tempered.

Tempering takes martensite and reduces the hardness and instills toughness.
The higher the temperature the tougher and softer it gets. This process is usually performed in one or two hour cycles. On most knife steels, the temperature for tempering is from 350 to 450°F, notice I said most.

So yes you can temper steel in your oven, but it must frist be hardened.

Jim A.

 

[islandmike]

well As always guys thanks for the help. I think for now i may want to just send it to a poor and pay to have it done.. Thanks for the help and the info..

let the searching being....

 

[Rob!]

Still curious Mike. What kind of steel is it. Even a pro will need to know that. The first blade I groud (HA! Filed!) was just mild steel from the home depot. That stuff can't be hardened or tempered.

There are lots of steels out there - many from scrap - that will make a decent knife - old files - truck springs - old sawmill blades - and the good stuff is realtively cheap too - many can be had for less than $10 a blade.

Rob!

 

[islandmike]

this was an old saw blade from the mill i work at.. It is 1/8 inch thick.. And was used as a cut of saw...

 

[Rob!]

Well, that's a better start than I made. For starters, the steel was already hardened and tempered - probably softer than youd like it but useable.

Whether it's you or a pro doing it, there will be a bit of guesswork because it's still somewhat uncertain what the steel is (though some good guesses could be made now.) TRy sharpening the blade and using around the kitchen without a handle for a while (unless you've already attached one). If you are satisfied with the balance between edge holding and ease of shapening, then just finish it as is. If you want it harder, there are some people here that could give some more educated suggestions than I can.

Got pictures yet??

Rob!

 

[islandmike]

No pictures yet, ima little embarrassed to put them on here, even after i complete it.. And thanks for the info..