decarb question

J

Jax knives

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May 25, 2020
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My first 1095 heat treat, 5 min soak at 1500* and quench in 130* canola oil. Temper 2 hrs at 400* and repeat.

Question: If I need to go to 120/220 grit to remove decarb then why in hell did I finish my blades to 320 before heat treat?
 
For several reasons:
1) A smooth surface is less likely to propagate a crack.
2) Because deep hardened scratches are a LOT harder to sand out than shallow hardened scratches.
3) There is more surface area exposed to the quenchant at 320 grit than at 120 grit.
4) It will speed up post-HT sanding a lot.

220 grit is enough pre-HT, but I usually go to 400 grit.
 
Stacy
Kind of a off topic question and unrelated but curious none the less.

If a quy has availability to a heat treat oven what would be the advantages of using carbon steel and dealing with added work of decarbing and a steel with no corrosive/rust protection other than material cost itself?
 
Good morning, Jax.
I'm not Stacy, but here's my 2 cents. One reason is, in general, plain carbon steels are easier to sharpen, which a lot of people like. Another is that some folks prefer the patina that the non stainless attain with proper care and aging, and it's easier to forge weld for damascus blades for most folks.
You should check out Larrin's site: KnifeSteelNerds.com
Here's an article answering that question https://knifesteelnerds.com/2018/09/10/carbon-vs-stainless-steel-in-knives/
 
Decarb isn't the issue.

A HT oven opens up the ability to HT steels that are not suitable for a forge HT. The only steels that are simple to HT in a forge are 1080/1084, 1070/1075, and 5160. 1095, O-1, 52100, and most of the other carbon steels are best done with soak times at specific temperatures in a HT oven.

The stainless and high alloy steels have to be done in a HT oven at controlled parameters. They are normally wrapped and sealed in a stainless steel envelope. You could wrap carbon steel, but it isn't worth the trouble. The latest decarb experiment seems to be in spraying it with a graphite spray coating. Others use ATP, Brownell's, and other anti-scale coatings. Most just put the carbon steel in as-is and remove the decarb in the finish grinding you have to do anyway.
 
Not yet. There is a thread running about it. The issue seems to be that we can't get the Blaster Extreme in the USA.

I have had good results with Turco II, and my homemade version of it. Another successful thing I have used is a thin wash of satanite.
 
Jax knives said:
Stacy
Kind of a off topic question and unrelated but curious none the less.

If a quy has availability to a heat treat oven what would be the advantages of using carbon steel and dealing with added work of decarbing and a steel with no corrosive/rust protection other than material cost itself?
Click to expand...

If you're forging, it's a lot easier to forge some 1084 than stainless steel, just sayin...
 
I will tell you this. What ever finish you put on your blades run it parallel to the blade and make it the same on both sides. We get aebl blades that will be rough ground perpendicular on one side and not ground at all on the other. These blades will come out of the plates looking like a banana. My recommendation is to always leave the flats as thy come from the mill. Do not grind them before heat treat.
 
weo said:
I read on another forum that this doesn't help with decarb. Have you tried yet?
Click to expand...
I am the one (The Old R.A.T.) who started using graphite spray for decarb/scale protection. I have written several papers regarding the process and results. I have asked others to try it and after two intrepid knife makers tried, they stated clearly that it works. Anyone who says it doesn't work probably hasn't tried it. Our research and testing shows no decarb or scale. I even test hardness through the graphite--no problem. Also, you don't need the high temp stuff. I buy mine at Home Depot--cheap and effective. Take a look at some of my papers addressing procedure and results on my DIY site, www.bellablades.com. Good luck and have fun!
 
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