Having problems with Aldos' 1/8" CPM154

J

John L

Joined
Oct 28, 2004
Messages
1,330
I make slipjoints. I have made a lot of slipjoints and never have had this problem with any steel except Aldos' CPM154 in .130 or so thickness. I profile the blade, fit to within about 5 thous. to spring in open, half stop and closed position. I cut nail nick, stamp my name and cut the choil which is a triangle and is common to slipjoints generally. I have cut them in 10-12 different steels and different thicknesses. My blades, in CPM154 from Aldo and Aldo alone fracture at the choil, almost every time. It does not happen in CPM 154 at 3/32" or in any other steel from him. Could it be improperly annealed or....? Should I anneal again as if it never was? Unfortunately I have a lot of this steel! Any solutions or comments welcomed. I would not cut the choil but I bandsaw it before hardening and cannot after. I could cut in with a Dremel abrasive wheel but should not have to it seems. I understand this triangle forms a stress but why in just this steel and just in this thickness? Hmmmm?
 
Hope this doesn't derail the thread, but I was just out in the shop today realizing that I don't actually know how to normalize 154/D2/440 etc, or what sort of pre-hardening heat cycles might be appropriate. Maybe someone will chime in...
 
Seems a question better addressed with Aldo as you are an experienced smith with self diagnosed issues with his steel. Give the man a call, my initial impressions ordering a small batch of 1084 were that he's just a top notch guy to deal with. Give the man a call.
 
You can't normalize an air hardening steel as you will end up with hard martensite !! You must give it a sub-critical anneal , 1200 F for a couple of hours.
 
Thanks Mete...I will give it a go and see what happens. Scooternut....I had asked Aldo but received no reply a while back. I have used his stuff for years now and enjoy him thoroughly. Aldo is not the problem! Probably my problem but cannot get it figured out for some reason.
 
John L,

You seem to be focused on the right thing. As you already know Aldo is a pretty good guy. He will help any way he can. What some people who have never been to his shop don't realize is that he's basically a three man operation over there. His son, another young man and Aldo. They fill a lot of orders. They are busy, busy, busy. If Aldo doesn't get back to you right away give him some time and check back.
 
How exactly are you heat treating/tempering?

If I understand you correctly, you are experiencing fractures AFTER temper? Correct?
 
Lets see some pics might help with diagnosis.

I do not use choils of any kind anymore or jimping for the simple fact that during testing I have snapped to blades both at a choil or jimping. Structurally it is not good ever sense I have stopped I have never missed either one. I actually still have a really nice blade from cpm154 that I used to love until I made one just like it with out a sharpening choil and I like it a lot better because it does not snag on anything anymore.

If you absolutely need the choil try a round one.

A good preheat treat, treament is ramp kiln at 1275 to 1275 hold for 2 hours air cool. This gives me very good results.

Also I fix any warpage in the tempering cycle by clamping blade straight and running a full temper cycle then water quench. Any warps will be gone.
 
I have three blades with choils in the oven now at 1275. Will air cool after and then do my usual heat and see what happens. The fracture always occurs at the end of the "V" or choil, and is about 1/8" long. Traditional slipjoints need choils and round ones do not look right.....hence ...the V. I have made over 1250 slipjoints and this only happens with ALdos' .130" CPM154.
 
Heated to 1275 for three hours and air cooled. Then heat treated as usual.......VOILA! no cracks. Thanks to everyone.

John
 
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