Need forging advice!

T

Tuck

Joined
Jun 29, 2003
Messages
29
My first forged knife was a total failure. I Used bearing race (52100 I think). After h.t., I was shining it up for tempering. I dropped it and it broke like it was glass. Real coarse grain structure! Bad material, bad thermal treatment or bad forging practices?
 
Don't claim to be any knd of forging expert, but my first question would be as to whether or not you normalized and or annealed it during forging and/or before heat treat.
 
Yeah, I heated it until non-magnetic and cooled in ashes 3 times (that was the only way I could come close to drilling holes in it)
 
Hey Tuck, Is it possible that the blade became too hot? Holding the blade at too high a temperature can cause grain growth. Ssounds like it hardened okay. You might try normalizing by heating just too critical then cooling in still air until no color remains, use a dark corner or dark area for judging color. I usually do it three or more times, then I bring it back up to critical and anneal by placing it in vermiculite at least overnight. forging at too high a temp can also cause grain growth. Good luck
 
I do almost same as BRTATCK, at least first part. I "flash normalize" as Ed Fowler puts it(bring up just to critical, allow to come back jsut to magnetic again, then bring it right back up to non magenetic) twice and then do a full normalize. But now that I have a vermiculite(or pearlite? can't remember, and don't wanna walk in other room away from fan) bucket setup, I will be adding an anneal step too. I'm only doing stock removal, but anything that might help performance of the knife. Plus I know I have a tendency to let it get a little hot at times grinding. nothing to burn out carbon, but enough that between that, and not knowing for sure how it might have been treated at plant, I'd rather take the few extra little steps to get best knife possible.
 
Tuck,

You got it too hot upon the final quench. FYI, an overheated (coarse grain) blade will naturally harden better/deeper (though coarse is still not what you're after). Also, dropping a blade before a temper can also bust a fine grain blade just as easy. Practice makes perfect. Keep on forging. You'll get it. :cool:
 
First ..Don't drop a full hard blade as it will break almost every time:D :D :D
Did you edge quench it or full quench it,if edge quench then you should have seen a coarse grain back with a fine grain edge.Did you check it with a new file to make sure it was full hard by having the file skate over the hardened area,if it didn't skate you didn't get it hardened properlyand should have tried the quench prossess again..
As said before keep practicing and you will get it Just don't give up.This is half the fun of making knives,figuring out what you did wrong and then learning how to correct it.
Good Luck,
Bruce
 
According to Jim Hrisoulas 52100 is one of the most difficult steels to use.
If you're a beginner, start with something easier, as 1075 or C70. I sue C70, which is analogous to your 1075.
1050 may be even easier, but 1075 will allow you more carbon to play with. After heating, forging, normalizing various times, heating again for quench, you probably will end up having around 0.50 C in the steel anyway, so using 1050 would end up with too soft a steel.
 
Part of the demonstation of heat treating thomas Gerner gives is to heat a piece of steel. Harden it and the smack it with a hammer it snaps like glass as you say. However then he continues on to demonstrate tempering the blade to a hard but not britle blade. Don't get down on your forging. It just may be that your not going to be a juggler.

I used baring race myself so did a mate. we got blades out of it but they were very prone to rusting and very hard under the hammer.

If your going for the recycling well done. I would try going to the car wreckers and get some leaf spring and some coil spring.

Avoid areas thet are prone to fractures. The problem is if the spring has had a hard life it may be developing a fault. It is a great source of cheap steel to practice with. Bash up half a dozen rough blades and practice heat treating etc.

I temper the spring blades after hardening in an overn at 218 degrees celcius for an hour 2 hours when I forget to take it out. It tempers the hole blade. No special harmon lines etc. It is not the high tech way of edge quenching that some guys do but it will get you a sevicable knife. if you are having trouble. Next tip get yourself along to anyone who is running a course and learn all the ways.
The blade is polished when I put it in and the colour change is to a light straw/gold. If it goes dark brown or blue you have got it to hot.
 
Simple steels are much better for the beginner since they are more forgiving.The more complex the alloy the more critical the heat treating and forging, for 52100 max forging temp is 2100F. Hardening temp is 1550F. Hardened blades should be tempered immediately ( leave out the dropping step,untempered steel is very brittle)
 
I can't believe no one has said to use material that you KNOW the make-up of. You said you THINK it's 52100. I've spoken with several of the metallurgists at the local bearing shops and they've all told me the greater majority of bearings used are surface treated mild steel (i.e. case hardened).

My recomendation is to pick up some good steel of KNOWN make-up...it won't cost you nearly as much as using old materials and having to do guess-work.

Nick
 
Tuck, Sorry I didn't read your post carefully. As a metallurgist who has worked in the bearing industry I can say that 52100 is a common bearing steel. However there are many others including case hardening types. So you r problem is compounded .You don't know the alloy therefore you don't know the forging or heat treating temperatures. As a beginner it is best to get a simple steel of known composition and work from there.Nick is right.
 
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