06-14-2018, 10:47 AM
Thanks for the responses Bud, Grepper and Subwoofer. For Bud and Grepper your logic follows ours with regard to the evidence that has been presented to date. Both of you have recognized, however, that the information presented to-date is far from complete or definitive and that realization is much appreciated. If the following study data turns around or contradicts as we and our fellow outside SET testers progress with this study it would be far from the first time that a research project did a 180° (or a 90°) midstream.
Subwoofer, the results we have obtained so far may be interpreted by the reader as they see fit but we guess that you are asking "how we interpret" the information gathered so far. So here goes:
You wrote "Just to double check, was the original intent of this test to see if the process of sharpening changed the properties of the steel at the edge, making it behave differently to the rest of the blade steel? "
This is absolutely correct in reflecting our purpose.
Then you followed that sentence with this in parenthesis "(and therefore potentially casting doubt over the validity of the results from the SET)"
This was not our purpose. Let's just stick with the first part of your statement for a moment. We know that edge apexes behave differently than the steel behind the edge apex. We know that HRC60-62 edge apexes can be rolled past 90° and then returned to their original orientation and done so repeatedly. Edge apexes therefore demonstrate a level of ductility that the balance of the blade seems not to enjoy. Edge apexes also do not seem to demonstrate the general yield strength characteristics of the blade as a whole. Edge apexes, deflected a mere 10°, do not demonstrate elastic deformation properties (they don't return to their original state/position post deflection). The blade, as a whole does. So the question then is "why is this?" One theory was that the very act and process of sharpening the edge creates this ductility in the apex. If this were true then two possibilities came to the forefront; "plastic deformation" and/or "foil properties". The very act of grinding an edge can be defined as an exercise in plastic deformation so the question then becomes " does the plastic deformation that may occur during the grinding operation change the hardness characteristics of the steel?" Soft steel is ductile, hardened steel is more brittle. This seemed to be a logical place to begin so we designed an experiment where the hardening process was conducted post sharpening. What are the initial findings of this experiment? Post hardened edges still demonstrate significant rolling characteristics. At first blush, it would appear that plastic deformation during the sharpening process is not, at the least, the major contributor to edge rolling. What remains? Foil properties and/or some physical property that we have yet to consider.
Please remember that that this test was merely a subset of the work we hope to achieve. We think that the inference you took away from the test is an interesting one and worthy of further thought so thank you. We look forward to your own findings with the SET tester and thank you very much for contributing to this work with your thoughts and questions.
Subwoofer, the results we have obtained so far may be interpreted by the reader as they see fit but we guess that you are asking "how we interpret" the information gathered so far. So here goes:
You wrote "Just to double check, was the original intent of this test to see if the process of sharpening changed the properties of the steel at the edge, making it behave differently to the rest of the blade steel? "
This is absolutely correct in reflecting our purpose.
Then you followed that sentence with this in parenthesis "(and therefore potentially casting doubt over the validity of the results from the SET)"
This was not our purpose. Let's just stick with the first part of your statement for a moment. We know that edge apexes behave differently than the steel behind the edge apex. We know that HRC60-62 edge apexes can be rolled past 90° and then returned to their original orientation and done so repeatedly. Edge apexes therefore demonstrate a level of ductility that the balance of the blade seems not to enjoy. Edge apexes also do not seem to demonstrate the general yield strength characteristics of the blade as a whole. Edge apexes, deflected a mere 10°, do not demonstrate elastic deformation properties (they don't return to their original state/position post deflection). The blade, as a whole does. So the question then is "why is this?" One theory was that the very act and process of sharpening the edge creates this ductility in the apex. If this were true then two possibilities came to the forefront; "plastic deformation" and/or "foil properties". The very act of grinding an edge can be defined as an exercise in plastic deformation so the question then becomes " does the plastic deformation that may occur during the grinding operation change the hardness characteristics of the steel?" Soft steel is ductile, hardened steel is more brittle. This seemed to be a logical place to begin so we designed an experiment where the hardening process was conducted post sharpening. What are the initial findings of this experiment? Post hardened edges still demonstrate significant rolling characteristics. At first blush, it would appear that plastic deformation during the sharpening process is not, at the least, the major contributor to edge rolling. What remains? Foil properties and/or some physical property that we have yet to consider.
Please remember that that this test was merely a subset of the work we hope to achieve. We think that the inference you took away from the test is an interesting one and worthy of further thought so thank you. We look forward to your own findings with the SET tester and thank you very much for contributing to this work with your thoughts and questions.