First Blade ever... I need help

[hogworthy]

This is my first actual blade I have ever made... full disclosure... I reground a sawzall blade and made a paring knife out of it. (super flexible)

But this is my first attempt at a "real" knife. I wasn't too enthusiastic about grinding a blade to shape, so I chose to forge one.

It is hand forged from 1/4" 5160 from Jantz.

1. Triple normalized
2. Annealed
3. Triple quenched in diesel oil at 150-160 F
4. Triple tempered at 350 F for x3 two hour cycles (as per Ed Fowler)
5. Soft drawn back with a torch while the cutting edge was cooled in water

6. Broke in half after about 35-40 degrees of flex while trying to straighten it, although it wasn't really bent that bad in the first place, I thought it would've flexed more than that.

Any help would be greatly appreciated.

My thoughts...
-not tempered at a high enough temperature?
-soft draw back not deep enough?
-crazy looking crystal structure in hardened portion of blade... not sure why? Obviously too hard!!!


Check the pics and any tips and tricks would be greatly appreciated.

 

[Stacy E. Apelt - Bladesmith]

I really suggest you read more before continuing. The stickies and a search will get lots of good info. I won't go as far as to say that the info you read from Ed is bad, but lets just say that many metallurgical folks don't agree with his advice.
The BF search engine is:
https://www.google.com/cse/home?cx=011197018607028182644:qfobr3dlcra


For your blade problems, there are so many, but here is a basic list:

There is no need to run a bar of steel from a supplier through those steps to normalize and anneal it. It comes that way. If you are going to forge the knife, it was a total waste of time, anyway. The first forging heat destroyed any change you made.

It looks like you had a crack in the blade at the spine. This could have been from forging too cold or a quenching problem.

The grain looks a bit coarse. This has nothing to do with being too hard. It has to do with being too hot in HT. How are you heating the blade and how are you determining the temperature?

Normalize after all forging is done and before grinding. Normalizing refines the grain and prepares the blade for hardening.

Quench only once ( unless it didn't harden right and needs to be done again). Multiple quenches on simple steels usually cause multiple problems.

Diesel oil is not a good quenchant. Use a gallon or more of canola oil, or get a gallon or more of commercial quenchant.

The oil temp should be 120-130F. 150-160 is far too hot.

Temper twice at 450F for one hour each. 400F is a minimum starting temper for 5160, IMHO. 350F is too low for 5160.

There should be no need to draw the spine softer, but that is mostly a personal choice. Your method should have been OK unless you got the spine red hot.

Flex is a factor of geometry. Hardness and steel type have no real effect on flex.....thickness does. Hardness and steel type will determine whether the blade breaks or bends permanently. At 40° most blades would snap. There are several ways to fix a warp. A search will give many threads of discussion.

 

[hogworthy]

Sorry for any confusion. The steel came annealed from Jantz. The normalizing and HT process I stated were all done AFTER the forging process.

Too hot in the HT process... I will fix that.

Diesel oil... I will buy some quenching oil.

Reduce quench temp... I can do that.

Increase temper temperature... done.

Soft draw only got the spine to a dull black color... should be fine there.



Thank you so much for your help... I think I was expecting a little to much out of a first blade anyway. Looking back on it I was most likely going way too high with the quenching heat of the blade. I was using a magnet to determine the proper temp. Any suggestions on a better method??

 

[Stacy E. Apelt - Bladesmith]

All that sounds good.

Get a magnet and use it to find the austenitization temp. When the blade stops sticking to the magnet, it is about 50-75 degrees below where you want it for the quench. Heat just a shade of red hotter and hold for a minute or two if your forge allows that. If the forge won't allow holding the blade at 1475-1500F for a few minutes ( ten minutes is optimal, but hard to do without a HT oven), just go ahead and quench when it is at the right temperature. Better a point or two softer than the max., than broken or ruined.

 

[SinePari]

Kudos to you on your first forged knife Hog. It might be a more difficult means to an end result, but you'll get better each heat. I had a hammer in a few weeks or so ago with some friends/fellow members (philll and esnyx), and it was the first time either one of them experienced forging with the hammer and anvil... While they both caught on quick and made some awesome blades, this last weekend their forgings improved ten fold. You get better with every heat and every hammer blow, especially when you seek to improve the skillset by watching videos, asking advice, and sharing your work with others....

Enjoy learning mang.