What do you know about Decarb of steel?

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?
How much?
I'm not telling what I think I learned until I hear from some of you.
Pete Stanaitis

Reply to
Pete S
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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
Reply to
--------------------------------------------------------- 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.
Pete Stanaitis ----------------
Reply to
Pete S

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