the strangest thing

[LOKI VINK]

Hi everyone.

 

So a couple of years ago made my first knife,.... it was a small tanto.

 

not really knowing about critical heat at the stage and non magnetic, i heated the blade and quenched it, I was curtain i did a good job and started working on it, cleaning polishing etc. . . I left the blade and forgot about it. . . so this morning i found it in all its glory still shiny after 5 years. . . knowing that the first time I heat treated it, I did it wrong.

 

I reheated the blade and let it cool, then reheated it to critical and quenched it in used motor oil. . .

 

Now here is where I raised my eyebrow and cursed at the tanto for it not becoming brittle, not even a bit harder, but remained soft, even though i did everything right. . . let me add, that this metal i used was meant for oil quench. . and is spring steel.

 

any one care to take a guess as what went wrong?

 

[jake cleland]

for most steels, critical and non magnetic are not the same thing (actually they're never the same thing, but there are enough simple steels where they are so close as to make no difference for it to be a handy tool) and you need to train your eye to see recalescence (shadows forming in the blade as the phase change uses energy followed by a marked brightening as the change is completed) - there are plenty of oil=quench steels where critical is several hundred degrees hotter than non magnetic, and even with some simple steels, you'll generally have to go 50 - 100f hotter than non mag to get any depth of hardening in slow oil.

[LOKI VINK]

thank you so much for the advice. . do you think that heating and quenching the steel and reheating etc like i did had any effect , or could have gone wrong, because normally, when the steal is heated above its critical to normalize the steel, i can re-quench. . . id like to try and take the knife and heat it up again to normalize and quench to see if i can make it hard. . think its possible? or wil the structure of the steel get too stressed

[jake cleland]

shouldn't be any problem re heat treating - i wouldn't bother re normalising, either the previous quench had zero effect, or else it was basically just an extra normalising cycle. multiple heats above critical don't stress the steel, in fact the opposite, but it can refine the grain too far to harden effectively. i would just heat it up(in the dark) until you see the recalescence, hold for a few seconds, and quench. it would be helpful to know what the steel was from...

[timgunn]

Do you know what the "spring steel" actually is?

 

I know that EM45 is a spring steel available in the UK. It's a Silicon-Manganese steel and needs higher-than-normal-Carbon-steel temperatures for Austenitizing: well above non-magnetic. Could you have something like this?

 

It will harden, it just needs a higher temperature, so all is not lost if that's what you have.

[Sean H]

Don't worry too much about it, it's a learning process and hey at least it didn't do anything worse than stay soft. Hell i worked with a Ukrainian blacksmith yesterday at my local guild. He just popped in, got bored, helped me do some forgewelding, then went to work making a blacksmith knife. He took stock that we know to be 5160, beat out a knife shape, refined it, annealed it, then hardened it in water! After hardening it, he has me hold a piece of mild stock as he takes a hammer and taps the spine of the blade, carving chunks out of the mild!

[LOKI VINK]

wow Sean thats quite sumthing else haha

 

sorry for the late reply.

 

I am using EN45, and yes its about the same as EM45. i think, to be honest ive never heard of EM 45.

 

And yes Sean, its like you say, its a learning process. I will add some pictures later so you can see what im doing and working on. . its real interesting. . . i heated it a second time just now . . and well i think the fire got too hot, , it kinda melted the point of the tanto right off haha. . but out of the ashes comes a new creation.

[jake cleland]

the hardening temperature for en45 is about 1630f, 200+ degrees hotter than non magnetic. if you've burnt the tip (which won't happen until you hit about 2600f), you'll need to cut it back to clean steel and re normalise at least 3x, before another hardening attempt.

[LOKI VINK]

thats what i thought .

 

well live and learn. . at the end it all comes down to practice.

 

Yea my fire is pretty hot.

[son_of_bluegrass]

Since you know the steel, I suggest a search for the proper heat treating protocol. Some steels require a soak at temperature to get the full effect of heat treating.

The temperature given above is quite a bit hotter than non-magnetic.

 

ron

[LOKI VINK]

thank you ron, ill look into it.

 

unfortunately my phone does not want to connect to the PC so, sorry guys i cant share any pictures regrettably