Noob knife broke.

dirtyphil

dirtyphil

Joined
Mar 19, 2014
Messages
165
I've seen threads on this subject but can't find my answer. I built a small break drum forge and put in a skinner in O-1, and a skinner in 3/16" 1095. I immediately put in the oven at 450 gor 2 hours. Both were red/ orange hot and non magnetic, used canola oil. Id seen on the youtubes a fella proofing his blade by bending it in a vise. He slightly bent it side to side. When I did it it broke in half. Solutions? Thanks, Phil
 
You described the HT process out of sequence. To be sure you understand, it's this order of events:

1) Bring blade to non-magnetic and hold at that temp for required soak time
2) Quench properly (whether in oil. air, or on plates, depending on steel)
3) Temper correctly (usually multiple passes in 400 degree oven for hour(s) at a time)
4) THEN test the blade
 
Of course it broke

Stop trying to bend it

and


find a better way to control the red hot heat you have obtained.
 
Last edited:
tryppyr said:
You described the HT process out of sequence. To be sure you understand, it's this order of events:

1) Bring blade to non-magnetic and hold at that temp for required soak time
2) Quench properly (whether in oil. air, or on plates, depending on steel)
3) Temper correctly (usually multiple passes in 400 degree oven for hour(s) at a time)
4) THEN test the blade
Click to expand...
I did that. I put in forge, pulled out to check magnet (nuthin) so I put back in then put immediately to quench. I then did 2 hours at 450 in the oven
Was it too hot in the forge is the only thing I can think of...
 
To me it sounds like you got the blade too hot and caused grain growth. What does the grain in the steel look like where it broke? It should look like a solid piece - like fine velvet. Large grain causes it to be brittle and looks like sand.

With all that being said, both O1 and 1095 need a long soak at temp to get maximum hardness. You are better off using 1080 or 1084 if you only use a forge to HT.
Jason
 
jawilder said:
To me it sounds like you got the blade too hot and caused grain growth. What does the grain in the steel look like where it broke? It should look like a solid piece - like fine velvet. Large grain causes it to be brittle and looks like sand.

With all that being said, both O1 and 1095 need a long soak at temp to get maximum hardness. You are better off using 1080 or 1084 if you only use a forge to HT.
Jason
Click to expand...

The break isn't clean, it's rather rough, looks like when you crack open a rock and there's all that rough fools gold inside.
 
Bending is a function of thinness and blade geometry, not blade quality, how well the quench went, or final hardness.
A double edged razor blade ( guys under 30 will have to google that) will flex 180 degrees and return to straight .... all while being around Rc60. A 1/8" hunter at Rc57 may snap when bent even 10 degrees.

Knives are bent as a destructive test, not as a quality test. Breaking the test blade will tell you how much it resisted bending and how fine the grain is....nothing else.
 
dirtyphil said:
The break isn't clean, it's rather rough, looks like when you crack open a rock and there's all that rough fools gold inside.
Click to expand...

Yep, grain growth. Steel goes nonmagnetic around 1425 or so, and stays nonmagnetic after that regardless of the temp. You got it too hot. Likely it "went" nonmagnetic alot earlier than when you tested it.
 
jawilder said:
To me it sounds like you got the blade too hot and caused grain growth. What does the grain in the steel look like where it broke? It should look like a solid piece - like fine velvet. Large grain causes it to be brittle and looks like sand.

With all that being said, both O1 and 1095 need a long soak at temp to get maximum hardness. You are better off using 1080 or 1084 if you only use a forge to HT.
Jason
Click to expand...

The break isn't clean, it's rather rough, looks like when you crack open a rock and there's all that rough fools gold inside.
 
Is there any off-color (darker than fresh metal) spots any where on the edge of the broken surface? Possibly indicate that steel was over-heated and cracked during quench. Suspecting a crack because even with grain growth (and beside geometry), you can flex a 450F tempered blade a little bit without it snapped in half.
 
dirtyphil said:
The break isn't clean, it's rather rough, looks like when you crack open a rock and there's all that rough fools gold inside.
Click to expand...

That is grain growth. Usually caused by excess heat (either during the forging process and/or during the heat treat process.

Normalizing will help, but will do no good if you don't have a grip on your proper heat treat temps and times.
 
The bend had nothing to do with this blade failure. It would have broken eventually since the grain was so large. Since you are using a forge, don't put the blade in and let it sit. Constantly move it back and forth so that it evenly reaches temp. Quench the tip in oil if it gets too hot so the rest of the blade can catch up. Also, if you don't have any way to control your temps, make sure you turn all the lights off and do this in the dark so you can see the true colors.
 
1095 doesn't require a long soak.

As bluntcut stated, a tempered blade should flex a little bit, even if the grain is huge.
 
Sorry to best a dead horse, but say I see that it's too hot... Is there no fixing that or can I let rest and try again. Tomato red?grassyass
 
You can normalize three times and try again. Try and shoot for each cycle to be slightly less hot than the last one. Then austentize and quench again.
 
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