05-09-2018, 01:00 PM
Picking up where I left off...
(Thanks for fixing the thread, Mr. Grepper)
Mike Brubacher explained a few days ago;
(Quote) "This experiment is a big deal to us though because it represents the very clear opportunity to see if sharpening, in and of itself, somehow significantly affects the yield strength characteristics of the steel. If it doesn't, we move on. If it does we then can investigate if this is true of all sharpening methods or just some and to what degree." (Unquote)
I really didn't understand the true nature of the goal of heat treating sharpened edges until I read this. I've been pondering the variables in this equation for a few days, and I'm hitting a wall.
I certainly appreciate your effort to try to decode the theory of micro heating and edge softening due to sharpening, Mr. EOU. Maybe this has been one of the goals of the SET all along. At any rate, I think the SET should be our best opportunity to answer this question.
While we have been pondering the affect of hardening sharpened edges, we are overlooking another factor of greater significance to determining the affect of micro heating the EOTE of these blades.
If the hardness of the EOTE is so tenuous as to be affected by a completely un-observable, indeterminably small amount of heat, how much more would the infinitely greater affect of tempering have on the EOTE?
Not only do we really not know if the EOTH is overly affected by hardening, we are trying to determine if virtually no heat has a minor influence to an amount of steel that has just been subjected to an enormous amount of heat.
IMHO, we are realizing why no one ever sharpens blades before HT. The EOTH is much too fragile to come away unscathed.
The current standards of not taking edges below .010- .015" prior to heat treat have been aided by advances in HT. Not only that, but standard procedure mandates removing several thousandths from the edge to get down to homogeneous steel.
If you hang out on sharpening forums much, I'm sure you've seen questions posed to the properties observed on factory edges. Most often it's from people appalled to see chippy edges on their brand new blades. It's very common to receive input guiding them not to worry about it. It's normal to assume that blades have not been ground back far enough to relieve the amount of steel that has been over-affected by the extreme heating and cooling during HT.
I'm sure we all had some concern that heat treating sharpened edges might not be appropriate. After all, nobody does that... ever. Brad claimed heat treating sharpened edges probably won't affect sharpness much. That's probably accurate. The amount of the increase in volume during phase change to martensite in steel with 1% carbon is about 3%. With inert gas shielding the affect of normal oxidation at 1500°F is magically diminished.
We could hope that the sharpness of pre-sharpened blades post-HT could remain mostly unaffected. That would be fine if that's what we wished for, but that is not what matters to us or anyone else.
What matters to everyone is the performance of the edge of a brand new blade. To that end, everyone takes certain measures to avoid over-affected steel to remain on the edge of a new blade.
I hope this exercise helps explain why certain procedures have developed into normalcy for the millions of new blades heat treated each year. I also hope this helps explain why certain procedures have developed into normalcy regarding the sharpening of hundreds of millions of edges per year.
I hope the people with questions pursue answers to their questions to the best of their ability. Perhaps EOU and BESS testing testing devices will shed new light on significant misconceptions. That would be very cool, and please do not think for one second that I wouldn't be the first to congratulate my esteemed colleagues.
I feel like an old dog. I've made mistakes like every dog my age, and (accidentally) been kicked and stepped on. I can handle it. I know I won't be in the right place every time. I'm just happy to still be in on the chase.
(Thanks for fixing the thread, Mr. Grepper)
Mike Brubacher explained a few days ago;
(Quote) "This experiment is a big deal to us though because it represents the very clear opportunity to see if sharpening, in and of itself, somehow significantly affects the yield strength characteristics of the steel. If it doesn't, we move on. If it does we then can investigate if this is true of all sharpening methods or just some and to what degree." (Unquote)
I really didn't understand the true nature of the goal of heat treating sharpened edges until I read this. I've been pondering the variables in this equation for a few days, and I'm hitting a wall.
I certainly appreciate your effort to try to decode the theory of micro heating and edge softening due to sharpening, Mr. EOU. Maybe this has been one of the goals of the SET all along. At any rate, I think the SET should be our best opportunity to answer this question.
While we have been pondering the affect of hardening sharpened edges, we are overlooking another factor of greater significance to determining the affect of micro heating the EOTE of these blades.
If the hardness of the EOTE is so tenuous as to be affected by a completely un-observable, indeterminably small amount of heat, how much more would the infinitely greater affect of tempering have on the EOTE?
Not only do we really not know if the EOTH is overly affected by hardening, we are trying to determine if virtually no heat has a minor influence to an amount of steel that has just been subjected to an enormous amount of heat.
IMHO, we are realizing why no one ever sharpens blades before HT. The EOTH is much too fragile to come away unscathed.
The current standards of not taking edges below .010- .015" prior to heat treat have been aided by advances in HT. Not only that, but standard procedure mandates removing several thousandths from the edge to get down to homogeneous steel.
If you hang out on sharpening forums much, I'm sure you've seen questions posed to the properties observed on factory edges. Most often it's from people appalled to see chippy edges on their brand new blades. It's very common to receive input guiding them not to worry about it. It's normal to assume that blades have not been ground back far enough to relieve the amount of steel that has been over-affected by the extreme heating and cooling during HT.
I'm sure we all had some concern that heat treating sharpened edges might not be appropriate. After all, nobody does that... ever. Brad claimed heat treating sharpened edges probably won't affect sharpness much. That's probably accurate. The amount of the increase in volume during phase change to martensite in steel with 1% carbon is about 3%. With inert gas shielding the affect of normal oxidation at 1500°F is magically diminished.
We could hope that the sharpness of pre-sharpened blades post-HT could remain mostly unaffected. That would be fine if that's what we wished for, but that is not what matters to us or anyone else.
What matters to everyone is the performance of the edge of a brand new blade. To that end, everyone takes certain measures to avoid over-affected steel to remain on the edge of a new blade.
I hope this exercise helps explain why certain procedures have developed into normalcy for the millions of new blades heat treated each year. I also hope this helps explain why certain procedures have developed into normalcy regarding the sharpening of hundreds of millions of edges per year.
I hope the people with questions pursue answers to their questions to the best of their ability. Perhaps EOU and BESS testing testing devices will shed new light on significant misconceptions. That would be very cool, and please do not think for one second that I wouldn't be the first to congratulate my esteemed colleagues.
I feel like an old dog. I've made mistakes like every dog my age, and (accidentally) been kicked and stepped on. I can handle it. I know I won't be in the right place every time. I'm just happy to still be in on the chase.