Tran Posted July 15, 2012 Share Posted July 15, 2012 I suppose many people know about this process, but I have not seen it on IFI. I have found that by using an aerator (low pressure air compressor in this case) in a "slack barrel" that low carbon steel will harden to the point that it is brittle. Any air supply should be enough to aerate the water, (bellows, hair dryers). I have the use of sodium hydroxide and have in the past used it to harden low carbon steel. The use of the aerator seems to harden as well or better and will not upset osha (maybe). It will also knock off scale, like salt water and sodium hydroxide. All in all it is seemingly safe and effective. Maybe it will work with RR Spikes. The reason that I used plastic buckets is that this is experiential and they were the easiest to work with. Any way, try it before you knock it. Link to comment Share on other sites More sharing options...
Rich Hale Posted July 15, 2012 Share Posted July 15, 2012 Interesting,,what was the low carbon steel that you tested? 1018,. A 36?, or another? i have also not seen this on this site..let us know please. Link to comment Share on other sites More sharing options...
Dave Hammer Posted July 15, 2012 Share Posted July 15, 2012 Super swisher...... Link to comment Share on other sites More sharing options...
Steve Sells Posted July 15, 2012 Share Posted July 15, 2012 normally we wish to avoid vapor in a quench medium I am assuming the agtitation stirs and prevents vapor from pocketing on the item you are hardening? even so I find it hard to fathom mild getting "brittle hard" as there are limits because of the carbon content Link to comment Share on other sites More sharing options...
Tran Posted July 16, 2012 Author Share Posted July 16, 2012 Mr. Hale, I don't know what type of steel this is, went to the hardware store and asked for square bar, flat bar, angle bar. Went the the warehouse and picked out what it wanted. It sparks like low carbon steel. Mr. Sells, I too don't understand how it works I am hoping that someone will try it and see if they have the same results. I have pictures of the two peices that flaked when struck. The first it a peice of flat bar 1X1/8" it cracked when it was put into the "bubbler", I ground the unbroken part and tried to cut into sheet metal. The part that was hardened and unhardened broke in two at the conjunction. So I heated the square bar to non-magnetic hardened and atempted to cut and piece of "parent bar". One of the corners of the square bar flaked off, but it did put a dent it. That is why the edges are not square. After the flat bar broke I put the hardened end in a vise and bent the unhardened end. The square bar will be used as a hot cutter, it fits the hardy hole, kind of. I haven't tempered any yet, but will try that. Link to comment Share on other sites More sharing options...
pkrankow Posted July 16, 2012 Share Posted July 16, 2012 Non-magnetic isn't hot enough to harden low carbon steel from. Consult some phase diagrams for steel to see what I mean. While you are looking up phase diagrams look up some TTT curves for steel so you can understand how speed of quench affects hardening. A36, the likely material you purchased, is "mystery metal" in that the chemistry is not fixed, it is based on specification of the final product. It can have up to 40 points of carbon, but usually won't have that much carbon.Mild steel can frequently "cut" into the parent stock, but will dull in the process. Grinding an edge on is all it takes. maybe not. I tried a little experiment and it didn't even go through the scale on the parent stock. That is some serious agitation from the bubbler. I have no reason to doubt it would increase the speed of quench over plain water because it may be forceful enough to disrupt the vapor layer, even though bubbles are involved already. I doubt it is significantly faster though. I guess it would be a cheap experiment to try at least. I would be surprised if it performs as fast as Superquench or even heavy brine. Steel seemingly *CRIES* because of how fast the quench is in heavy brine. (It does make a noise that is fairly unique.) I have not personally tried Superquench, and I am not sure if I will in the future. The cost of making Superquench is close enough to buying good steel that for just a few items it doesn't make sense to use and store for an indefinite time. I think you got a bar with unusually high carbon content and it simply hardened in a normal manner with a water quench. Phil Link to comment Share on other sites More sharing options...
ThomasPowers Posted July 16, 2012 Share Posted July 16, 2012 I'd suspect that 1: you were using A36 and 2: the agitation was the aspect that made the difference---have you tried the same test with just a hose shooting water against the same pieces while immersed in the bucket? I'm sure you know that publishing after one uncontrolled experiment with very low n is a risky business; but thank you very much for sharing this so others can do their own experiments! Link to comment Share on other sites More sharing options...
Tran Posted July 18, 2012 Author Share Posted July 18, 2012 Further investigation revealed that both Mr. Krankowski and Mr. Powers are probably right about the type of metal, I personally know little about metallurgy. Mr. Krankowski may also be right about me getting it a little too hot, but not by much I used a magnet. I tried the bubbler on stainless and it seems to anneal it if anything at all at least on the samples I have. I found some of what I think is a different type of steel (angle form another source) and it was able to be hardened, but it was not brittle. Rebar hardened not at all, at least not the samples I have. I don’t have a wide source of black iron to choose from, whatever is at the hardware store. There was not only one piece of metal, there was flat bar, angle, and square bar that hardened in the same manner. Mr. Powers, I haven’t used the hose and bucket, but will try it later. That may well have the same effect. Yes, this was uncontrolled. The reason I posted the process was to show that one has another way of hardening low carbon steel without upsetting OSHA. As to the use of brine, I had forgotten reading about the Mongolians using this method of hardening arrow heads during the time of Genghis Khan, until Mr. Krankowski mentioned using brine. It has been around a while. I hope others do try this and do post their findings. Link to comment Share on other sites More sharing options...
pkrankow Posted July 18, 2012 Share Posted July 18, 2012 Rebar and hardware store steels are mystery metals with a high recycled content, and a strength specification, not a chemistry specification. What you are doing with testing samples of all the materials on hand was, at one time, a normal process to determine the type and quality of materials received, and if they had a suitable purpose. Well controlled chemistry on steel really is a modern thing that has only been around for 100 years or so. There are stories of companies receiving shipments of steel having workers spark test every bar, or a percentage of bars, in a load to determine if the proper material arrived. John Deere c.1843 http://www.gutenberg.org/files/34562/34562-h/34562-h.htm I do go back to my earlier statement that for many purposes buying a suitable grade of steel is cheap enough to outweigh the expense and bother of making up "Superquench". However if you can test some rebar, or other found material, and find it is suitable without much extra efforts, then all the better for making your own tools. There are a lot of tools made from "mystery metal" performing quite well. Scrap suspension parts from cars, a good source of high carbon steel, can often be had for cheap or free by asking at repair shops that often have to PAY to have the steel hauled off. Show dressed for work, ask politely, have sample trinkets to give, and the worst they can do is say "no" Leave the space neater than you find it and you will be welcomed back Phil Link to comment Share on other sites More sharing options...
ThomasPowers Posted July 18, 2012 Share Posted July 18, 2012 Yup going back to the olden days! Moxon's Mechanics Exercises, (1703) mentions testing the stuff you buy to see what it was good for as does, IIRC, "Practical Blacksmithing" (1889, 1890, 1891). As for brine quench, currently the earliest quenchant reference I have in my lumber room of a brain is "the urine of a small redheaded boy or a goat fed on ferns for three days" mentioned by Theophilus in "Divers Arts" written around 1120 A.D. For a long list of amusing old time quenchant suggestions "Sources for the History of the Science of Steel" has a renaissance excerpt with things like worm water and radish juice all said to be *much* better than plain water and imparting many properties to the metal that are impossible to do by quenching according to modern research. Hardware store metal is often quite marked up---I've found that it's sometimes possible to buy a 20' stick from a steel company for about the same amount as a 4' piece in a hardware store. If all you need are short pieces I was able to get drops from a medium sized ornamental iron company for free as they had to pay to get their scrap bin hauled back then and so I would go in and clean and neaten it and haul off a lot of steel on a regular basis, (and forge a trinket of two for the office...) If you can use longer pieces it *pays* to shop around! I live outside a small rural town in NM and it turns out that the cheapest place for me to buy steel is at an old time Windmill construction and repair company. They sell steel on the side and the bigger the buy they make from the big city steel places the cheaper they get it and so are happy to sell it to you on the side---for about 2/3 the cost of buying a 20' stick from the local lumber yard and without the 50+ miles each way to the next closest steel seller. Link to comment Share on other sites More sharing options...
ben11c Posted August 8, 2012 Share Posted August 8, 2012 Its a very difiicult but fruitful process of hardening low carbon steel Link to comment Share on other sites More sharing options...
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