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About Sakura

  • Birthday 04/13/1983

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  • Gender
  • Location
    Haaksbergen, The Netherlands
  • Interests
    Science, japanese culture, drawing, music.
  1. Sakura

    Loud bang

    Thanks! BTW The surfaces were perfectly clean and dry so I don't think it could be that. But I should learn to be patient hehe, I know, sometimes waiting is hard especcially when you have vacation and are bored.
  2. Hi guys, and girls. I've got a SKF ballbearing lying around and while I'm busy on another forging project I thought about throwing it in and hammering it out to a little knife. I'm planning on hammering it flat so I squish the round form into a flat bar keeping the balls in the middle. I want to hammer it in a rough knife form with the handle still being recognisable as a ballbearing but flattened (sort of) and making the blade side nice as possible but after etching still revealing the balls and inner structure (in a patternweld like way). It's a test so I'm actually not counting on making something nice but I just want to see how it works out. I can get more ballbearings if it doesn't work out, our machines eat them at work and they get quality controlled out very soon. My question(s): What should I do flux-wise? I thought about trying to dry weld it dipped in kerosene. What would you do? Use borax? And at what stage, already right at the start when it's stil round? Or just hammer it sort of flat and then clean it and apply borax before the final weld? Or maybe not weld at all to keep the hammered flat ball-and-cage structure even in the blade? I would like the final blade to be still recognisable as an ex-ballbearing. If you hammer it flat the steel cages might form a nice closed structure with the balls. Any suggestions are welcome, and mind me I'm a noob so don't hold back to treat me as such. Ps. Sorry for saying balls this much hehe.
  3. Sakura

    Loud bang

    Hi Guys. I got some M42 (or M35 I'm not sure, the material sheet names both for some weird reason) High Speed Steel (marked HSS) from work. It were saw bands with a grainy nitride coating and I thought they might be nice to try and weld. So I made some pieces and tied them together with steel wire and heated them to welding heat, I went for a bright yellow glow, maybe a bit to high because the steel got quite sticky. Anyways when I hammered it crackled really loud, at one point a report actually gave me a sharp beep in my ears. It was as loud as the illegal cracers we get here at newyearseve, really loud and sharp. I got a bit scared so stopped forging. I thought maybe the nitride layer might explode in some way at that pressure and temperature. Nitrous compounds even without oxigen can go explosive, for instance some metals (titanium) can burn in a nitrous atmosphere at the right temperature. I thought I'd ask first here if it's normal or if I was indeed right stopping before spinters of metal would go flying around in the process. I made it redhot one more time and quenched it in cold water just to see if it would harden. It did, without cracking but it did get very brittle, obviously, I didn't normalise, temper or anything. Just to test, and it did weld so except from the loud reports/bangs, and very loud indeed, it does look like good steel to work with. Has anybody any ideas, tips or sugestions? BTW I hammer with a wet hammer, like some japanese smiths, I know if gives of loud bangs sometimes but this time it was way louder. I also didn't use flux, I ran out and got impatient waiting on my order. I use a charcoal fire, probably a bit too high on air. Alloying compositions of common high speed steel grades (by %wt) M2 C 0.95 Cr 4.2 Mo 5.0 W 6.0 Co 2.0 M7 C 1.00 Cr 3.8 Mo 8.7 W 1.6 Co 2.0 M35 C 0.94 Cr 4.1 Mo 5.0 W 6.0 CO 2.0 Mn 5.0 M42 C 1.10 Cr 3.8 Mo 9.5 W 1.5 Co 1.2 Mn 8.0 Note that impurity limits are not included (with thanks to wikipedia) A foto of the raw material:
  4. Well I fired it up for the first time today. I got me a while before I had the right air/charcoal ratio, and at the end I got lazy so I went into turbine engine mode (far too much air). But it burns, I even managed to make something, I did cost me 2,5 kilo's of charcoal though. It doesn't look like much, and the wharped end annoys me but the edge is nice and center. It's an old axle of one of our machines. I gave it a 1mm thick edge so I can use it to split or put edges and notches in future workpieces when needed. Thanks for looking and the nice suggestions!
  5. Sorry I was off....I remebered a factor 23 from my study but I got mixed up. I did some searching and one mole (not litre hehe) of gas always gives off 22,4 litres of gas, since avogado's law states that (pressure x volume)/(number of atoms x temperature) is constant. Since a mole of hydrogen weighs 2 grams the one litre to 23 litre rule is quite absurd indeed. How could I be so wrong hehe, it's a scientists thing, so many equations and rules you just cant help mixing them up once eventually. And putting it in a dewar with a small opening is nothing short of suicide, it will blow and completely rip you apart with broken glass schrapnel. I usually use a dewar that has a bowl shape and is completely open at the top side so the rapid expansion won't be dangerous. The mist is pretty harmless. If our main tank pressure valve blows off it gives a LOT of mist but even standing a meter from it you'll only feel a slight cold. As I said before the cooling capacity is quite low, you can actually pour it over your hand without burning it. And it's a very big vessel, 300 litres, it usually fills a 4x4 meter area in thick mist when it does. You can easily breathe standing in it since that gas is so heavy that only a really thick layer will form at ground level. It allways provides a lot of entertainment when new and unsuspecting trainees stand too close. Priceless scaring the new guy on his first day, they got me too three years ago I still vividly remember it. Trust me Dough no man will hold it against you. The woman mind goes beyond any form of science and logic, and still they are such beautifull creatures.
  6. hehe well I might just pass on this one then. I was just curious if anyone here tried it or had the same wharped fantasy about the subject. You'll never know if it works if you don't try it but for now I'll pass on this one. If I do I'll definately tape it, the priceless image of some fool running around in a big steamy mess with a hot metal bar in his hands is probably worth the effort. I'm not that keen on big malty ales Howard. We as Dutch are pilsener type people, if I need something stronger then a Macallan fine oak on the side and a good piece of dried sausage will make me smile the whole night long.
  7. The solid to gas conversion in explosives you're talking about is a chemical process. Yes liquid nitrogen will produce a LOT of gas but if you do it outside in the wind you probably (heheh probably) won't suffocate. In case of the explosive type of solid-gas conversion you talk about a lot of energy comes from the breaking of the very strong molecular nitrogen-oxygen bond and indeed allso the generation of a lot of gas but it's the chemical bond breaking that makes an explosive explode. With liquid nitrogen you won't have this explosion because you don't have the explosive type bond breaking, it will only cook off very fast instead. This will allso mean a lot of heat is transferred from the blade to the liquid. I'd have no problem sticking a red hot piece of metal in liquid nitrogen, in a very windy place with an oxygen mask that is, maybe I'll be extra nice to my lab-chief so I can take a few litres home sometime. I'm absolutely sure the explosion you talk about won't happen, but the very fast cooking off might be quite spectacular. BTW the liquid to gas conversion is the same for all liquids, the volume changes by a factor of 23 if I remember correctly. I might go for a Grolsch in my hand, I work across from the brewery, in the east off holland it's allmost a crime to drink anything else.
  8. This might sound a bit steep beforehand but maybe it isn't. I work a lot with liquid nitrogen at work and that got me thinking. Has anyone tried hardening a blade in it? At first you might think "-192 degrees celcius thats impossible!" but is it? My experience is that the cooling capacity is quite low, even a small sample takes quite a lot of time to freeze. You can stick your hand in it if you do it quickly without feeling the cold, and yes I tried it, being curious is probably a bad thing in my case. A few reasons why I think it might work: -The cooling capacity is quite low as I said. The cooling rate might even be very close to water especially if the metal is still hot since a lot of the gas will boil off, and I mean a LOT (white mist everywhere). With the added benefit that you won't get bubble nucleation on the blade, which I've heard could cause unwanted stress points during hardening, since the liquid will only touch the actual blade if its cooled to low temperatures. -It forms a insulating layer of gaseous nitrogen, this gives a very homogenious cooling which prevents cracking and wharping. -It might even slightly nitride your edge for extra hardness. Has anyone here actually tried it?
  9. Hey guys! This might be a bit off-topic so sorry beforehand. I took a bunch of GEM laboratory razor blades with me from work. I have at least two kilo's . We discard them after only a few cuts so scattered around the lab there are many bins with "dull" blades we throw away, they are actually still sharp as *insert very hot place*. I asked my chief if I could take them home and I could since we considder them garbage after first use. They have a piece of metal folded around one of the sharp sides so they won't cut your fingers. I think about welding them and folding so that the carbon content of the low carbon dull side evens out the high carbon blade. Anyway, does anybody know what the approximate carbon content of these type of razor blades is? If anyone is interested, we throw away at least a kilo of these blades and scalpels every week.
  10. I'm just trowing it in here, so mind me if I'm talking rubbish. I don't know what steel you've used for your knife but you could considder nitriding. Might be easyer then trying to weld/solder a tungstencarbide bit to it, since it would not weld and soldering might be a bit prone to breaking if not done properly. Nitriding is only possible with steel, titanium and alumnium as far as I know. But if you can do it you'll end up with a very hard point. It maybe could be as easy as heating the piece to the austenite region (in case of steel) and quench it an a very concentrated ammonia solution (90%) repeat this a few times and temper. Or stick it in liquid nitrogen instead of an concentrated ammonia solution if you can get your hands on it. I'g go with liquid nitrogen, it's not that hard to get your hands on and a lot less corrosive and stinky then a concentrated ammonia solution. 90% Is VERY concentrated, I'm a chemical engineer and I even don't usually handle it if I don't really have to. Don't make the layer too thick, a nitride layer is very brittle so a thick layer will break and chip off, one time might be sufficient. Industrial nitride layers are usually only a few atom layers thick (usually 5 to 10 atom layers, which translates to roughly 50nm)and still improve the durability of the part at least ten times. And make it sharp, this will improve the nitride density of the tip. Correct me if I'm wrong, it might be just a wild theory. I can't back it up with practical experience.
  11. How about the zatoichi for Takeshi Kitano's movie Zatoichi?
  12. Thanks for the info, you have a nice and clear site! But the things you say are exactly the reasons I'll go for a blower first. Maybe this winter I'll start on a fuigo too, so I have the time to make it work without haste, but for now I want to concetrate on hammering metal.
  13. The nitride coated high speed steel was another find, it has nothing to do with the 304 steel we talked about. The 304 or 3401 (that's stamped in the bar) is just a nice beam I found that got me curious enough to start a topic. I found the high speed steel at work, its M35, and it's nitride coated because it used to de a sawband in one of our big sawmachines. BTW It's not the shiny gold coating you're probably familiar with, its a grainy blueish other form. One of the guys from the technical staff gave me a heads up so I managed to take some home in exchange for a piece of cake. We use the sawband for cutting very hard polymer and fiber housings with embedded metal so we need the nitride layer for added durablility, heat dissipation and to reduce friction of the sawblades. I know for sure its M35 HSS since I've seen the material sheet. Alloying compositions of common high speed steel grades (by %wt) M2 C 0.95 Cr 4.2 Mo 5.0 W 6.0 Co 2.0 M7 C 1.00 Cr 3.8 Mo 8.7 W 1.6 Co 2.0 M35 C 0.94 Cr 4.1 Mo 5.0 W 6.0 CO 2.0 Mn 5.0 M42 C 1.10 Cr 3.8 Mo 9.5 W 1.5 Co 1.2 Mn 8.0 Note that impurity limits are not included (with thanks to wikipedia) I got about 4 kilo's of it, divided in 0,8mm thick 1meter long strips, with sawteeth one one side . I think if you get it hot enough you could maybe weld it trough the nitride layer since it's so grainy and embedded in the metal. If it welds it may give some very special metal. It's probably not doable but it's allways nice to mess with new things. That grade of steel is air hardening so for knives it's maybe a bit to steep, it will eat my tools I'm afraid but there's no harm in trying. They allso gave me a nice big SKF ball bearing. Sorry I'm wandering now, what's the policy here for keeping topics on-topic?
  14. Thanks, I'll look into it. Even if it's useless I love browsing trough metal bins and seeking out the compositions of the countless grades of steel in the world nowadays. I even found a piece of Hastelloy today at work
  15. It's the last week before vacation so I got a bit bored at work. So I thought let's write something. I have an engineering degree in chemistry and had quite a lot of material science classes and I tried to adopt this to something understandable worth posting. Mind me, this is by no means a complete essay and may contain some faults. The behaviour of steel and even more multiphase alloys is so complex and the field is so big that I really couldn't even handle a small part of it in the short time given to me. Nonetheless I hope it's worth giving a quick readtrough for yall Main source: Materials, science and engineering (an introduction) published by Elsevier. And off-course my best friend Wikipedia...life has become so easy for an information addict now A theoretical summary of steel behaviour. Crystal structure. Metal is generally found in the three types of cubic arrangements. The most simple one, the simple cubic structure is hardly found, polonium is a rare example. The simple cubic arrangement is not favourable for structure formation since it leaves open to many spaces in between atoms which is unfavourable for structure formation. Metals are usually found in a Face-Centered Cubic arragnement (FCC) and Body-Centered Cubic (BCC) arrangement, at room temperature. Fig.1. common crystal structures for metals. Iron usually exists in the body centered arrangement as are most of the other hard metals like tungsten and chrome, this is by no means a guideline though. The face centered arrangement is typical for metals as lead, gold, copper, aluminium and silver. This is at room temperature and atmospheric pressure, almost all metals may exist in other structures (even very exotic ones) at higher pressures or different temperatures. This will become an interesting factor since this transition between arrangements is a way in which you can form the attributes of steel alloys, but more on this later. Metals as we use them can be considered polycrystalline, this means consisting of a bonded mass of little crystals. This is not completely true since the crystal structure of metals isn’t a true crystal structure because metal atoms aren’t covalently bonded like the atoms in true crystals are. This means bonded by sharing an electron pair. Metal exhibits metal bonding, the positively charged cores consisting of protons and neutrons float in a sea of shared electrons. This structure does exhibit the same crystallinity as real covalently bonded crystals. But since there are no shared electron pairs (“real” bonds) this crystal lattice is more malleable; to move the crystal structure internally no bonds have to be broken and formed again. This is also the reason why we have so many strengthening mechanisms for steel. Impurities or vacancies give raise to lattice defects. These defects can cause local points of stress, compression and tension in the crystal lattice. These defects and grainsizes can be engineered so steel can exhibit so many forms and qualities. Fig.2. Edge dislocation lattice defect. By making use of these defects or the polycristallinity we can strengthen metal by the following three ways. Strengthening by grain size reduction. Polycrystalline metals have a matrix of metal grains. These grains have a differing lattice orientation and they come together in a grain boundary. The smaller the grains the larger the amount of boundary surface is in between the grains of the metal per given volume. These boundaries stop the movement of dislocations. The ease of which a metal is capable of deformation is directly related to the mobility of dislocations in the metal crystal lattice. A grain boundary stops the movement of a dislocation thus strengthening the metal. A metal almost always breaks along a grain boundary. If this grain boundary is relatively finer then the surface is greater so this gives a second mechanism by which a finer grain strengthens the metal. The forces of breaking have to be distributed over a greater surface so the crack stops sooner. Grain size may be regulated by the rate of solidification from the liquid phase, usually slower cooling gives crystals more time to grow and results in courser grains. Grain size may also be affected by plastic deformation followed with a proper heat treatment, for instance forging. Fig.3. Typical grain boundary pattern in a stainless steel pipe, etched and magnified to 600x. Fine carbide particles outline the grain boundaries. Solid solution strengthening. Every crystal structure has defects, the most common are vacancies and (self)interstitials. The picture below gives a nice image of these defects. Fig.4. Common point defects. In the case of steel alloying you make use of the benefits an “impurity” can give. In fact you could see any alloying metal as an impurity. These impurities tend to diffuse trough the metal matrix and seek out places where they’ll fit in nicely. For instance an edge dislocation as shown above (Fig.2.) will cause stresses in the matrix, an impurity could diffuse towards the start of this dislocation and take in a place that relieves stresses around this dislocation. Also will the impurity fixate this dislocation preventing it to move to one of the boundaries of the crystal structure. By relieving stresses in the metal matrix and preventing the movement of dislocations in this way it makes the metal tougher. High purity metals are for this reason almost always softer then alloys composed of the same base metal. Strain hardening. This phenomenon is better known as work hardening. A metal that is worked at a temperature significantly lower then the absolute melting temperature, usually at room temperature, will harden. The metal will become harder and tougher, the tensile strength becomes greater. The trade-off in this case is ductility, the metal will become less ductile and more prone to cracking tearing or chipping. The strain hardening phenomenon is explained by interactions of dislocation effects in the crystal lattice. Working cold metal gives more dislocation defects since the metal isn’t “liquid” enough to nullify dislocation effects caused by an externally applied force. The dislocation density in the metal rises and these dislocations come closer to each other. As discussed earlier dislocations in the crystal lattice cause stresses. If these stresses come closer to each other they give raise to a repulsive interaction. The result of this is that the motion of a dislocation is hindered by the presence of other dislocations. As the dislocation density increases, this resistance to dislocation motion by other dislocations becomes greater. Thus, the imposed stress necessary to deform the metal increases with increasing cold work. All these mechanisms can work together or against each other to any extend to engineer the properties wanted of the metal. For instance. The normalising and tempering of metal during and after forging or hardening are ways to relieve stresses in the metal matrix to make it malleable. Or in the case of tempering letting dislocations move and rearrange to relieve stressed regions and make the structure more homogeneous and destress the brittle zones formed by the extreme forces of hardening. Normalising and tempering can also be methods for reducing grain size or make the grain size more evenly distributed. In the industry there is a wide array of treatments and temperatures to engineer a metal structure towards a point needed. If done at a certain temperature you can can recrystallise a metal for instance. But maybe I'll dig into that somewhat deeper a next time. Phase diagram of iron/carbon. We have all seen this one, the phase diagram of carbon steel. Now lets try to explain some things we see in it by what we’ve just read. Fig.5. Iron/Carbon phase diagram. The most important thing in this diagram for you bladesmiths is probably the austenitic region. In this austenitic region the metal goes from a body centered orientation to a face centered cubic orientation. These two different allotropes (the same element in a different orientation) have very little difference in practical characteristics but one very important one is that the austenitic steel can dissolve more carbon. By folding and forging steel in this region you can add carbon to your metal matrix. The big thing with the austenitic region is that if you'll cool it rapidly enough the steel won't transform back to a pearlite/cemetite matrix but something different. During the rapid cooling the dissolved carbon doesn't get the chance to diffuse out of the iron matrix and form undissolved iron carbides in the metal (cementite), instead it will form a completely different form or steel. Martensite with a tetragonal body centered structure, this structure is similar to the body centered cubic structure only stretched in one direction so it's a rectangle instead of a cube. This tetragonal arrangement forms plate-like structures in the ferrite matrix that will give it significantly higher hardness and also will cause the remaining ferrite to adopt a finer grainsize and a more uniform grainsize distribution. This can be seen as a nice hamon if done properly, together with some other effects off-course. Some other interesting thing in this phase diagram is the cementite region. Above 6,5% carbon by mass you can't technically speak of a steel anymore. The steel has so much carbon in it's matrix at that point that it will transform to a ceramic, real cristalline, structure called ironcarbide. This is a very hard ceramic similar to the better known tungstencarbide (armor penetrators) and different in composition from titaniumnitride but the crystal structure is the same. These are some of the hardest ceramics known. The formation of cementite crystals can be engineered for in low carbon steel too, but this will result in enbrittlement. However a small amount of cementite crystals always exist in steel because of production techniques. BTW. I actually didn't know this but did you know every heated thing glows at the same colour at the same temperature, nomatter what chemical composition. The visibility may differ but any black body radiation (the purely thermal radiation of any object) is the same colour at the same temperature. Probably old news for you but I found it quite the discovery.
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