Different steels and decarb?

[Nylunds knives]

Is some steels more resistant to decarb then other?

If for example high carbon steels like d2 with 1,5% carbon less resistant to deacarb against a steel that contains less carbon?


Regards Jakob

 

[Nathan the Machinist]

That's a good question, I don't know the answer.

I do know that steels like D2 that need a long soak at high heat (1850) suffer worse than simple steels that only need a short soak at more moderate austenitizing temperatures (1500).

 

[sunshadow]

My understanding is that it is a solid state diffusion process, diffusion processes generally progress towards an equilibrium state so the higher the carbon content the more RELATIVE effect you will notice (it's not all that noticeable if you are working with 1040 and you drop to 1030, but if you drop 1095 to 1030 it makes a huge difference.

I may be completely off base on this, but that is my understanding of what I've observed under a microscope.

Mete are you out there?

-Page

 

[galadduin]

My understanding is that it is a solid state diffusion process, diffusion processes generally progress towards an equilibrium state so the higher the carbon content the more RELATIVE effect you will notice (it's not all that noticeable if you are working with 1040 and you drop to 1030, but if you drop 1095 to 1030 it makes a huge difference.

I may be completely off base on this, but that is my understanding of what I've observed under a microscope.

Mete are you out there?

-Page

This is reasonable, I wonder if the alloying elements do affect decarb process. For example as far as I know P content may block carbon migration pattern welded steels. Maybe there is some other alloying elements that does block decarb..
Emre

 

[mete]

Not only carbon but other elements too ! High silicon steels are especially prone to decarb !. Nature always is looking for balance . It wants to balance the carbon in the steel with that outside the steel.Always assume you'll get some decarb so leave a little extra material to grind off.

 

[Kevin R. Cashen]

Alloying has effects on decarb rates. "Tool Steels Simplified" by Palmer and Luerssen covers it quite well with a section on tests done by Carpenter labs illustrating these effects.

 

[Nylunds knives]

Thanks for the info :thumbup:


I discussed heat treating with another maker recently. He said he had tested ss foil when heattreting but couldn't notice any difference with or without the foil. He now heat treats plain blades in the oven and dosen't seem to have any problem with decarb. He uses 12c27.

Today I was searching the net for information about carpenter xhp and on carpenters official page it said something like, that high carbon tool steels could have more trouble with decarb the other steels.



Regards Jakob

 

[KnifeMaker.ca]

Thanks for the info :thumbup:


I discussed heat treating with another maker recently. He said he had tested ss foil when heattreting but couldn't notice any difference with or without the foil. He now heat treats plain blades in the oven and dosen't seem to have any problem with decarb. He uses 12c27.

What am I missing here? I would think any blade left unprotected for a 1950F heat treat soak would be pretty much garbage. If someone can't tell the difference between that and something done in foil, I wonder if he is doing something wrong with the foil.

Rob!

 

[Nylunds knives]

What am I missing here? I would think any blade left unprotected for a 1950F heat treat soak would be pretty much garbage. If someone can't tell the difference between that and something done in foil, I wonder if he is doing something wrong with the foil.

Rob!

I was thinking the same way...

His blades seems to be fine and hold the edge as good as any other 12c27 blade. I read an article in a Swedish knifemaking magazine written by one of Sandvikens own metallurgist who recomended about 5min at temperature for knifeblades in 12c27, so maybe the decarb won't have time to get as bad as when holding a blade at temperature for 30min or more. I honestly don't know...


Regards Jakob

 

[galadduin]

Oh!!! Tell me about the failed SS foil wraps, I loose about half of the thickness if I'm lucky when D2 or other high alloys left unprotected...

Emre