Kitchen Knife OC#4-(PART 2)englmanRank: #2169Adjust content blockingContent Blocking prevnext Prev Next WHO WANTS TO LEARN METALLURGY?! join list: englmanOC (684 subs)Mention Clicks: 19587Msgs Sent: 87597Mention History Part 1: You need to login to view this link This week I will be heavily explaining some of the Metallurgical Science behind heat-treatment. I hope I can make it at least a bit interesting for you guys and as comprehensible as possible!So as stated last week, here are the three test pieces that I will be working with. The primary result that I'm going to be searching for is to roughly assess the effects of soaking 01 tool steel. The left-most piece will be soaked for 10 minutes, the right piece for 5 minutes, and the middle piece won't be soaked at all. It was naughtyTo harden steel, we must bring it up to what is know as the critical-temperature. This is the state in which the steels crystalline structure changes from Ferrite and Pearlite, into Austenite. This temperature varies between steels, but the easiest way to test if you're at the correct temperature is to run a magnet over the steel(a retractable magnet is perfect for this). If the magnet sticks, then it is not there yet. If it does not stick, then you are at the correct temperature. Simple enough, AND alleviates guess-work or the need for expensive thermocoupling technology! Now, some Blacksmiths will tell you "You know when to quench by looking at the color of the steel." These 'smiths are barbarians. Color is not an accurate gauge for something as finicky as heat-treatment. I should know; I used to ONLY gauge by color! Too many things can affect the way you perceive the color and that makes this method horridly inaccurate. So when I started using a magnet, I became much more accurate and my knives became sexier.Some of you may be wondering, "But why do you soak the steel?" To you I say, "My my my, that's a handsome looking question sir or madam! Let me try to answer that in a way that doesn't make you regret asking" Without getting TOO into the Chemistry of steel, the short-hand reason for soaking ONLY HIGH-ALLOY STEELS is to allow the grain-boundary-segregated-carbides to evenly migrate back through the steel and create (for us) greater edge-retention. If you're interested to know more about the Chemistry of 01 tool steel, check out these links! Alan Longmire is very knowledgeable. You need to login to view this link You need to login to view this link So now the steels have been oil quenched and are at max hardness. This means that the crystalline structure of the steel has been locked into its most brittle, hardest structural form; The ultimate goal of quenching. But we don't want to keep the steel in this state. Martensite is far too hard in its unaltered form and can break like glass due to the jagged, almost "triangularly shaped" crystalline structure.So we must temper the steel. Whether the steel is quenched in brine, water, oil, air, or liquid nitrogen; it must be softened some to be usable. To soften(or temper) the steel, heat must be applied in a slow, steady, and controlled manner.~Temper Transition beetle~So what exactly is tempering and how do we temper steel more specifically? Well the good thing about working with known-materials is that they usually come with a data-sheet, or at least a sticker with important details. Here we can gain insight as to some of the major constituents of the steels chemical composition, what temperature to quench and in what medium. As well as what temperatures to temper at, how long, and what hardness-outcome we can expect from each. What exactly is tempering though? Tempering is the act of using heat to allow the carbon in the hardened steel to migrate more evenly throughout the metal, thus softening it. During quenching, carbon effectively gets "frozen" in specific positions, effectively locking the crystalline structure in its Austentitic phase(but without requiring the excessively high temperatures). This creates the Martensite structure: A very hard, jagged crystalline form. Stuff sounding redundant yet?The above is a basic chart that shows the structural phases of various steels based on carbon content, and roughly at what temperature to expect the structural changes to occur. In addition to quenching and tempering, I also feel it's important to be familiar with the terms normalizing and annealing. Normalizing is the act of heating the steel to critical temperature and then allowing it to slowly air-cool. This eases mechanical stresses that were put into the steel, either through forging or from years of working as a tool. Annealing is the act of softening steel to its most softened state. To do this, the steel has to be heated to the critical temperature and allowed to cool EXTREMELY slowly. It almost goes without saying, but annealing steels allows you to more easily grind/work them. Super worth knowing if you don't want to waste a lot of time, money, and effort messing about with harder-than-necessary materialHere I've cleaned the steel and am ready to begin tempering. I put all three pieces in our home oven at 400F for 1 hour, took them out to slowly cool in still air, put them back in for 1 hour(400F), and then let them cool again. WOO FOR THERMAL-CYCLING!!!I apologize that this came out a bit long and.. er.. "less than interesting" at times. I had no clue that I paused so much when talking Source for the "chalkiness" thing I mentioned: You need to login to view this link Metallurgy aside, I learned some applicable things in doing this minor 'research.' I learned that I actually CAN and probably SHOULD grind the first large bevel on my knife before I heat-treat. Above, I have the line scribbed as to where it will stop.Only got through with ~1/3rd of the first bevel this week, but I've been busy on this and a second post for Sunday! Oh well, no rush ay? Don't want to mess it up AND I'll likely be starting school again soonish as well. May as well get used to doing a bit less forgingApparently you can oil quench blades with relative success as long as you leave the 'edge' about the thickness of a dime(~1/16th inch). Above is the progress so far.WHAT'S THIS!!?!??! Thanks to the help of my lovely Patrons, I was able to feasibly purchase some brilliant editing software! Look forward to me learning how to use this to improve the quality of my current content, possibly branch into different types of videos soon, and maybe make some DANK MEMES along the way! That's all for this week! If you stuck around until the end, you're a beautiful chap and I like the cut of your jib. I hope everyone enjoyed this and learned something interesting as well. I love this stuff so much and if anyone wants to know more, or has a question, just ask me and I'll do my best to answer everyone Thank you all so much for your continued support! Don't forget to thumb up if you enjoyed Have a great weekend FunnyJunk Very Special Thanks to My Patrons! Apprentice Tier: Phwoarr, Zekain, Killaavenged Power Hammer Tier: Ulcis Patreon: You need to login to view this link YouTube: You need to login to view this link Profile: You need to login to view this link join list: englmanOC (684 subs)Mention Clicks: 19587Msgs Sent: 87597Mention History Join the mention list if you enjoy my content! I post every Friday! prevnextTags: kitchen | Knife | OC | englman | Blacksmith | Blacksmithing | Metalwork | metallurgy | heat treatment I WAS MM MEMES nit SO I Fai. . t, ijt THEM IN FIRE... +276 -Favorite +Favorite Unblock User's Content Block User's Content
