Nakedanvil - Grant Sarver Posted July 13, 2009 Share Posted July 13, 2009 I hate the term "normalize"! All other thermal treatments are specific to the steel at hand and the rate of temperature change required, air harden, oil harden, water harden. Or anneal at a cooling rate of 50 degrees per hour etc., etc. How come normalize is "one size fits all"? "Heat to critical, allow to air cool". If I air-harden an air-hardening steel is it still "normalizing"? Does an eighth-inch thick piece cool at the same rate as a 2" thick piece? Even air, oil and water harden only refer to a one inch cross-section. You can get a proper hardening on water-hardening steel in oil if it's only 1/8 inch thick. And a four-inch thick piece of 4140 won't harden worth a darn in oil. Just some things to think about, as if heat-treating wasn't mind numbing enough. Quote Link to comment Share on other sites More sharing options...
divermike Posted July 13, 2009 Share Posted July 13, 2009 agh you are killing me, I was just starting to get my mind wrapped around the other stuff and now you are opening a whole new can of worms, especially if you are talking copper!! Quote Link to comment Share on other sites More sharing options...
David Einhorn Posted July 13, 2009 Share Posted July 13, 2009 The names reflect the *intention* of what you are trying to do to the steel, for example: 1. Normalize - reduce or eliminate the stress caused in the steel by forging. 2. Anneal - soften as much as possible. 3. Harden - to make the steel hard 4. Temper - to bring the level of hardness to a less brittle state, so that the tool is less likely to crack or brake. You would likely normalize a tool to reduce the stress in it. If you used the annealing process, yes you would reduce the stress in the tool, but it would take longer. This obviously is an oversimplification. I expect that someone will point you to a web page with all the explanations on molecular structure. Quote Link to comment Share on other sites More sharing options...
Glenn Posted July 13, 2009 Share Posted July 13, 2009 BP0078 The Metallurgy of Heat Treating Quote Link to comment Share on other sites More sharing options...
Nakedanvil - Grant Sarver Posted July 13, 2009 Author Share Posted July 13, 2009 Unicorn: I realize the "intention", it's just that normalize is the only one that has a "one size fits all" process i.e. "heat to critical, air cool" with no regard for a particular steels tranformation rate. With quenching, the rate is specific and we either air, oil or water quench etc. Quote Link to comment Share on other sites More sharing options...
Charlotte Posted July 13, 2009 Share Posted July 13, 2009 (edited) Unicorn: I realize the "intention", it's just that normalize is the only one that has a "one size fits all" process i.e. "heat to critical, air cool" with no regard for a particular steels tranformation rate. With quenching, the rate is specific and we either air, oil or water quench etc. Actually if you look at the crucible steel site and look at their heat treat info they give specific temperatues for every thing including nomalizing and IIRC time at temp. My first paying job was operating heat treating furnaces.(1965) The started me off on the continius normalizing furnace. As I recall normalizing for most alloys was fairly rapid. Higher alloys were done in car type furnaces according to a strict schedule. The stainless steel furnaces, both normalizing and annealing were strickly for the old hands and very finicky. With water baths, special pickle treatments etc. I think you are objecting to the very casual way we talk about with no regard to alloy or temperature or geometry. If that is what you are cocerned about then your point is well taken. Although I wonder how many people work high alloy steels without paying attention to the manf. data sheet? Edited July 13, 2009 by Charlotte spelling Quote Link to comment Share on other sites More sharing options...
Quenchcrack Posted July 13, 2009 Share Posted July 13, 2009 (edited) Normalizing does imply specific temperatures based upon the carbon content of the alloy you are using. When you say "heat to critical" do you mean the upper critical or lower critical? You should be heating to the upper critical which is a sloping line on the Iron-carbon phase diagram. Only at the eutectoid point (.78%C) does steel become instantly austenitic. All other carbon contents need to be heated HOTTER THAN NON-MAGNETIC TO ACHIEVE FULL AUSTENITIZATION!!! Non-magnetic is at about 1440F which is not fully austenitic on most of the steels we use. We need to be heating to 1750F on low carbon ( like 1018) to about 1550F on 4140. Edited July 14, 2009 by Quenchcrack Quote Link to comment Share on other sites More sharing options...
Nakedanvil - Grant Sarver Posted July 14, 2009 Author Share Posted July 14, 2009 Guess I didn't word my post as well as I could have. I understand the process. If someone asks "how do I quench this", the first response is "depends on if it's air hardening, oil hardening or water hardening steel, what are the specs"? Same with annealing and drawing. But when it comes to normalizing, there are any number of posts here that say "normalizing is heating to the upper critical temperature and air cooling" period. Right? It is often taken as gospel that that is all you need to do. It certainly implies something different to Quenchcrack than to most others. I just wanted to raise awareness that there can be more to it than that. Steel grade is just one thing. If a cooling rate needs to be achieved then obviously size of the part matters too. An 1/8 inch thick flat cools a lot faster than a 3" round. Quote Link to comment Share on other sites More sharing options...
HWooldridge Posted July 14, 2009 Share Posted July 14, 2009 Sounds like you are recommending "normalize" would be a better description if tied to a specific alloy and/or size. Some of the tool steel suppliers already state heat treating time for certain thicknesses - maybe they should also list normalizing guidelines (where they apply). I agree that 'normalizing' A2 or 1060 the same way will yield entirely different results. Quote Link to comment Share on other sites More sharing options...
Charlotte Posted July 14, 2009 Share Posted July 14, 2009 The one thing that bothers me about the way normalize is used is that the element of time is often left out. As you point out that Air cool becomes air quench in thin sections! Thanks for bringing it up. Even in a continious furnace hold times were 5 to 10 min and the cool down was often to a given point above ambient. With a hold time limited by the number of zones available. As I said they were simple alloys but exact compositions were not given the operator only a lot # and and engineering heat schedule to follow. Quote Link to comment Share on other sites More sharing options...
David Einhorn Posted July 14, 2009 Share Posted July 14, 2009 (edited) Answers also depend on whether one is doing general smithing using mostly mild steel and assorted mystery metals, or whether the person is doing critical temperature applications such as knife making with known tool steels. Those such as myself that tend to fall more into the mild steel and mystery metal category may give answers that apply to the applications we work with, unless the question includes the information that the application parameters include critical temperature control with tool steels. Mainly this results from our using, almost exclusively, iron and steel that is water hardening, and from the lack of need for critical temperatures in tools that are going to be used for hand punches and the like. One does not put a lot of heat treating into a punch that is going to be repeatedly sunk into orange-hot metal. Since a knife will not be plunged repeatedly into orange hot metal, it will more likely retain its heat treatment. The punch is either quenched in water after each use, and/or re-treated after it looses its functionality. Thus to the general smith, normalizing tends to mean heating something up and placing it under the forge to air cool since most applications are low carbon steel, water hardening steel or iron (if you have access to iron). If you mention that you want to normalize a thin length of high carbon tool steel, then the answer more likely will suggest a bucket of vermiculite. Depends on the applications that the smith normally works on. You might even get a different answer if the smith is spending that day making pattern welded blades; depends what is foremost in his/her mind. I have to switch mental gears to talk about the critical applications. Different gears, different level of critical treatment, different answers. :D Edited July 14, 2009 by UnicornForge Quote Link to comment Share on other sites More sharing options...
divermike Posted July 14, 2009 Share Posted July 14, 2009 aggghh! you guys are killing me!! so many details, my head is swimming!! Can't I just get it hot and hit it? sheesh! well maybe someday it will all be clear, I wonder how the 1700 smiths got along without all this debate material...? Quote Link to comment Share on other sites More sharing options...
Steve Sells Posted July 14, 2009 Share Posted July 14, 2009 The 1700's smiths didn't have to worry about it because they didn't have Stainless steel, Powdered metal technology alloys, or any other alloy steels. As for definitions, this is the knife section, so its natural to assume its about blade steels, if not post is in general. Blade steels requirements can vary so much its almost a requirement to state what steel is being used in order to get any meaningful information in the first place :D Quote Link to comment Share on other sites More sharing options...
David Einhorn Posted July 14, 2009 Share Posted July 14, 2009 True the question being in the knife section would hopefully guide the individuals answering a question towards blade steel oriented answers. But is it not also true that we should not assume that a person answering his questions either on the forum or at a guild meeting: 1) is answering it from the knife blade oriented oriented thinking or experience 2) noticed when they pressed the button for "New Posts" that the question was under the category of knives My posting was simply to possibly raise awareness communication is a tricky less than perfect thing, and that sometimes one could *gosh* get non-bladesmithing answers to a bladesmithing question. The 1700's smiths didn't have to worry about it because they didn't have Stainless steel, Powdered metal technology alloys, or any other alloy steels. As for definitions, this is the knife section, so its natural to assume its about blade steels, if not post is in general. Blade steels requirements can vary so much its almost a requirement to state what steel is being used in order to get any meaningful information in the first place Quote Link to comment Share on other sites More sharing options...
Nakedanvil - Grant Sarver Posted July 14, 2009 Author Share Posted July 14, 2009 You makin' fun a me, boy?;) Quote Link to comment Share on other sites More sharing options...
Steve Sells Posted July 14, 2009 Share Posted July 14, 2009 well if the shoe fits........... (and if it don't, you should call a Ferrier ) Quote Link to comment Share on other sites More sharing options...
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