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Misc. updates: I added some toughness numbers that I had previously been unable to track down comparing 440C and 154CM to the 154CM article. I also added a summary of a very interesting new journal article about the effect of grain size on steel toughness to the Grain Refinement article.
Now on to the review…
Mastersmith Kevin Cashen recently released a DVD all about heat treating 1080/1084 (they are nearly identical steels, which is why they are grouped together). I think this was a great idea. Cashen is known for giving entertaining and informative lectures on metallurgy. 1084 is a very popular steel for beginning knifemakers and there are countless discussions on the various knife forums about how to heat treat it. Furthermore, Cashen focuses a great deal of the DVD on heat treating the steel with a forge, which is often the tool at the disposal of a beginner. This DVD fills an important niche and I think it will be popular based solely on the subject matter being covered.
The Introduction
Cashen begins the video providing a short introduction on what the DVD is made to teach, who he is, and what the DVD will not cover. I like that he stated that the DVD will not teach you how to make the “ultimate” knife, but how to make a “good” knife, and he says that knifemakers sometimes become distracted by the “ultimate” goal. I think he’s right; there are many knifemakers trying out various odd forging and heat treating practices in an attempt to make their blades better than the next person. Many of the ideas they try out won’t work. Experimentation is good; however, many times they are trying out failing ideas because the knifemaker doesn’t know what the individual heat treating process is for that they are tweaking. Should I normalize for a longer time? A shorter time? Higher temperature? Lower temperature? Should I normalize multiple times? There is no way to answer those questions without knowing what one is trying to accomplish with normalizing in the first place. That, I believe, is one of Cashen’s major goals with this DVD: provide clear and simple explanations of the forging and heat treating process, what each step entails, and a specific process to accomplish those goals with 1084. General information is provided on what 1084 is good at, what it isn’t as good for, and why it is ideal for a beginner bladesmith.
The DVD
Kevin did a great job with this DVD. His delivery is natural and easy to follow. He never put me to sleep, which is test #1 with these types of how-to DVD’s. However, one might argue that I as a metallurgist was already more interested in the topic than the average person. He has an engaging and personable style which makes it easy to pay attention. There is some humor interspersed throughout as well; this isn’t a dry recitation of metallurgical facts. There are many visual aids including graphs, schematic diagrams, mcirographs, and many video clips of the different stages covered in the DVD. The video clips of the forging and heat treating process are particularly well done. You can see visually what a blade looks like as it is quenched in oil, or how a magnet sticks to (or doesn’t stick to) steel at high temperature, and “decalescence” and “recalescence” of the steel as it transforms to different microstructures. Despite the self-produced DVD, the quality of the material is high. This DVD is not simply a video of Kevin presenting at a hammer-in and slapping it onto a DVD. The production is high quality and it is obvious that it was a labor of love. There are no wasted words in the video, and probably should be watched multiple times for someone digesting the information for the first time. Because of that Cashen doesn’t go in any unnecessary directions or go deeper than is necessary. There were a few cases where I wished that the video was available in HD to be able to see the micrographs, videos, or graphs in better detail. Perhaps a digital copy in HD could be provided at some point if distribution and anti-piracy logistics can be overcome.
The How-To
The DVD was not designed to provide specific instructions on how exactly to operate a forge or how to forge a knife. It is assumed that basic knowledge of forging is already known prior to watching. I have never run a coal forge, and do not know how to run one after watching. The DVD focuses primarily on the approximate temperatures and times required for the different steps and the details of how that is accomplished is covered but the knowledge of how to operate one’s equipment is assumed. This is not necessarily a video on “how to make knives” but covers a specific knowledge area. That is not to say that it is a DVD of only concepts and not instructions, however. There are specific instructions for the steps that are relevant to the subject at hand such as the details of quenching while avoiding warping and other potential pitfalls.
Throughout Cashen makes reference to how to do each step with a forge or furnace, and mostly provides specific times and temperatures for each method. Sometimes he gives a range of temperatures that are acceptable and suggests experimenting to find out what will work best. Sometimes with beginners they want to be spoon-fed a little more and just want someone to give a specific temperature/time combination. Viewers will have to work a little bit harder than that and it’s probably good for them. One suggestion I would make would be to add a high-level summary of the entire process at the end of the DVD. If there was a one page summary of how to do everything from beginning to end first for a forge and then for furnace I think that would have helped wrap everything up. That would also help to differentiate between when he was referring to a process to use with a forge and when he was referring to a process with a furnace. And allow the knifemaker to have a clear view of the process as a whole.
The Metallurgy
Making metallurgy topics clear, digestible, and easily understood can be difficult. I experience that frequently when writing articles for this website, and I will get comments from some that my articles went over their heads. It’s not easy. Kevin Cashen did a great job with making things clear. He assumes that the viewer has no pre-existing knowledge on metallurgy and explains everything from the ground up, all the way back to atoms and diffusion. He makes simplifications where necessary and most of my minor complaints about the way metallurgy is covered would be nitpicking. Sometimes things must be “dumbed down” just a bit or only explained at a surface level to make them understandable to the beginner and also to maintain an appropriate length for the DVD. He explains very well the various processes such as what normalizing is and how it works, what happens during austenitizing (heating to hardening temperature prior to quenching), quenching, tempering, etc. and what goes on in the microstructure of the steel during each step. It is simple enough for the beginner but also thorough and comprehensive enough for the advanced bladesmith.
I have heard metallurgical explanations, presentations, and read articles from many very experienced knifemakers and Mastersmiths, and there can be a surprising amount of misinformation. This DVD does a much better job of covering the “true” science and avoids the common myths. He has obviously done his homework. Cashen also shows many of his own micrographs that he took of 1084 or other steels and the images of the microstructure are beautiful. He is an excellent metallographer.
In a few cases a term is used prior to introducing it, such as references to normalizing, etc. before the normalizing section. I think that is acceptable because there is little flow to the information if there is too much time spent upfront on defining every possible term. However, he does use the term “hardenability” a few times throughout the DVD, and while he later describes “shallow” and “deep” hardening steels he does not explicitly connect those terms to “hardenability.” That could be confusing for some because hardenability sometimes sounds like a term that refers to how hard a steel can be rather than the cooling rate required for achieving its peak hardness.
The extent of the properties described of 1084 provided by different heat treatments was limited to hardness either as-quenched from different hardening temperatures, or after tempering with different tempering temperatures. He also gives general recommendations for tempering temperature ranges for either fine slicing knives, heavy chopping knives, or general use knives. He also shows micrographs for the range of different hardening temperatures that one might use. However, he never describes what those different microstructures might lead to in terms of properties but simply says that different temperatures might be better for different applications. He shows an impact toughness tester at the beginning of the video and I was disappointed that no toughness numbers were shown for different heat treatments. That would have gone along perfectly with the different hardening temperature or tempering temperature recommendations.
There was one area covered that I think could have been clearer which is the description of the transition from magnetic to non-magnetic at high temperature. Cashen spends a significant amount of time on the Curie temperature which he describes as the point where the steel become non-magnetic. The Curie point is the temperature where ferrite (which Cashen calls “leftover iron”) becomes non-magnetic, which occurs at approximately 770°C (1418°F). However, the high temperature austenite phase is also nonmagnetic which 1084, as a eutectoid steel, reaches at approximately 1340°F or a few degrees higher to account for the rate of transformation. Therefore the steel becomes nonmagnetic at up to 78°F or so lower temperature than the Curie point, and that didn’t come across in the video. So the viewer may have a misunderstanding of what temperature the steel has reached when becoming nonmagnetic which may be significant if they are attempting to match the temperatures that Cashen is recommending in the video.
Conclusion
The delivery, information provided, video, and imagery are all high quality in Kevin Cashen’s DVD. It is a major upgrade over previously available videos and books created by a knifemaker for knifemakers. The metallurgy information provided is clear, the steps involved in heat treating are easy to understand, and the whole package looks professionally done. Kevin Cashen’s Guide to 1080 & 1084 is highly recommended for anyone who wants to know what happens during forging and heat treating, and why each step is done the way it is. There are many knifemakers with a couple decades of experience that have something to learn from the video. I’m looking forward to future installments on other steels.
Here is the link to buy the DVD: http://cashenblades.com/mathertonforge/index.php/for-sale/
Disclosures (or lack thereof): I was not given a free copy for review and I don’t receive any commission for clicks on the link above.
