How to Thermal Cycle Knife Steel (article and video)

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hi larrin. i'm working with 52100 now. from large diameter round bearing stock. so i have to flatten these. i take these up to yellow with acetylene. so it i can bend/bang them straight.

tried to simply take these to unmagnetic once, then air cool. then harden. 1 shade above unmagnetic. warped like fukn crazy. and it was totally unusable.
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then tried a very high temp one shot "normalizing" with acetylene after flattening. to get all tensions out. up to maybe light yellow. almost white.

then 3 cycles to just above unmagnetic, then air cool. in open air. now, hardening these i take them to like 1-2 shades above unmagnetic. dunk in a mix of hot hydraulic oil and motor oil. comes out hard as glass. and cracking these parts shows a grain size of almost 0. i cant ever see any grain. its just dull gray.
but its 0% unrepeatable i guess. i do this all by eye. with acetylene and propane.

after tempering 2x at 180C my bacho files just skid along.

yeah thats some anecdotal data for you. i feel i did good though.
 
hi larrin. i'm working with 52100 now. from large diameter round bearing stock. so i have to flatten these. i take these up to yellow with acetylene. so it i can bend/bang them straight.

tried to simply take these to unmagnetic once, then air cool. then harden. 1 shade above unmagnetic. warped like fukn crazy. and it was totally unusable.
---------------

then tried a very high temp one shot "normalizing" with acetylene after flattening. to get all tensions out. up to maybe light yellow. almost white.

then 3 cycles to just above unmagnetic, then air cool. in open air. now, hardening these i take them to like 1-2 shades above unmagnetic. dunk in a mix of hot hydraulic oil and motor oil. comes out hard as glass. and cracking these parts shows a grain size of almost 0. i cant ever see any grain. its just dull gray.
but its 0% unrepeatable i guess. i do this all by eye. with acetylene and propane.

after tempering 2x at 180C my bacho files just skid along.

yeah thats some anecdotal data for you. i feel i did good though.
The term is nonmagnetic rather than unmagnatic.

In the first case you heated to nonmagnetic instead of normalizing? Why?

Why are you heating with an acetylene torch? That leads to uneven heating which then leads to warping, etc.

Why use hydraulic oil/motor oil?

Why create extra problems for yourself?
 
The term is nonmagnetic rather than unmagnatic.

In the first case you heated to nonmagnetic instead of normalizing? Why?

Why are you heating with an acetylene torch? That leads to uneven heating which then leads to warping, etc.

Why use hydraulic oil/motor oil?

Why create extra problems for yourself?

yes of course is nonmagnetic :)

i had already taken the steel way above nonmagnetic, around forging temps i guess, when flattening it.
then i took it just above non magnetic once. and it didn't work out. it warped in the quench.

i use the acetylene because its free and i do it at work. when i get payed. :) and its fast. very very fast.

i use hydraulic oil and motor oil since this is what i have access to for free.

because free is free. 0 money spent. and its even better if i can do it all at work.
 
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