What do you know about Decarb of steel?

[Pete S]

I ran into some trouble making fire strikers work properly late this summer.
I have been making them for a long time and all of a sudden they quit
working. Using brand new 3/16" X 1/4" W1 from MSC. The trouble SEEMED to
start when I got into a new 3 foot bar.
After a lot of question-asking and some research and analysis, I think I
have solved my problem.
What do you guys know about decarburization of tool steels?
Why?
How much?
Examples?
Etc.?

I'm not telling what I think I learned until I hear from some of you.

Pete Stanaitis

[alv...@example.com]

Pete S <sp...@baldwin-telecom.net> wrote:
> What do you... know about decarburization of tool steels?

I don't-really-know-squat about decarburization of tool steels! :/
(other than what I've read, and which most of it I done forgot)

What I want to hear about is what you -think- you learned about
it and how you figure you know more than squat about it. LOL :)
But I can wait on that tho.

What I don't want to wait on is an answer to this question...

1) Pete, did you do any careful spark testing? xD

Alvin in AZ

[Pete S]

> What I want to hear about is what you -think- you learned about
> it and how you figure you know more than squat about it. LOL :)
> But I can wait on that tho.
>
> What I don't want to wait on is an answer to this question...
>
> 1) Pete, did you do any careful spark testing? xD
>
> Alvin in AZ

---------------------------------------------------------
Hello, Alvin.

ans. 1) I don't have any sense for "spark testing" at all. I don't know
whether the problem is my eyes or my brain. When this practice has been
demonstrated to me, I don't even see things the way the demonstrator says he
sees them. otoh, I do make sparks all the time with my strikers and I
notice real quick if they don't work right.

I have a long answer and a short answer to your first question. The long
answer is for later. Right now it's in a 2 page long Word document.
The short one:
Background:
Hot oxygen and hot carbon like each other a lot. They like to make carbon
dioxide. If I don't take appropriate steps to control this phenomenon,
the outer surface of the part will loose some of its carbon. Significant
loses can be as little as a few thousandths of an inch to as much as 1/8",
from input I have received.
I always assumed that scale forms faster in the fire than decarb occurs, so
I never paid it much heed.
-Apparently, the higher the carbon content in steel, the more rapid the
decarb.
-Decarb appears to slowed, but not stopped by other alloying elements.

Answer:
I caused the problem by becoming sloppy.

-Parts in the fire too long
-Parts reheated too many times while being fabricated while talking to the
crowd
-Parts held at heat too long while demonstrating non-magnetic property to
the crowd
-My rivet forge (used for a few demonstrations where I have to bring
EVERYTHING) has no firepot. I sometimes allow the fire to burn out too
much, allowing more air (oxygen) than needed to get to the part.
-Not removing enough scale on the working edge after hardening.

There.

Pete Stanaitis
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