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Thread: friendly conversation on A2 and chipping

  1. #16
    The composition of A2 should be the same from all steel makers. The problem is the size of the chromium carbides and the resulting micro cracks in the steel. When the steel is hot, the chrome tends to clump together and when it cools down this causes stresses in the steel. Irregular small cracks apear. This is typical for conventionaly made alloyed steel. PM steels are a solution to this problem because of its much smaller grain size. The problem happens during steel fabrication but can also worsen during heat treatment. But I suppose most heat treaters just use the standard recipe from the steel supplier.

  2. #17
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    Also knowing a bit about A2 and the application/composition of powdered metals (though not PM-V11 specifically), variability will definitely come into play with the heat treating part of the occasion.
    If the thunder don't get you, the lightning will.

  3. #18
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    I think the wood your cutting has effect, I cruised along quite nicely until venturing into harder hardwoods, then found that I had to make some changes to get more usable life from the blades. That was everything from Japanese steels to A2.

    My general consensus now is 34-35 degrees with A2, 32 degrees with 01, 30 degrees with blue and white steel with exception to mortise chisels which are 35 degrees and paring chisels which are probably under 30.

    I take alot of full length and heavy cuts with my jointer and so I dont want it wearing rapidly and causing me to reset it twice a day.
    Last edited by Brian Holcombe; 05-14-2015 at 8:10 AM.
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  4. #19
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    Brian, are you referring to chisels and planes? And if including planes, whether BU or BD?

    Regards from Perth

    Derek

  5. #20
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    I suppose I should specify, since I'm all over the map here;

    Japanese chisels; 30 degrees, paring chisels under 30 degrees, and mortise chisels 35 degrees

    A2 paring chisels ('Merican) I'm around 32 degrees.

    Bevel up planes, the only one I have I have an 01 blade and I'm around 32 degrees. I've reground the A2 blade to be incredibly cambered and I couldnt tell you what the bevel is.

    Bevel down; all are A2 and 35 degrees, that's jointer and smoother.

    One thing that doesnt get alot of press around here, but I absolutely love them; whatever Terry Gordon is using for his plane blades (joinery planes) is quite nice I keep them at the initial setting for and simply work them by hand. I've never checked anything with regard to their angle and have never had a problem with them being chippy.
    Last edited by Brian Holcombe; 05-14-2015 at 8:43 AM.
    Bumbling forward into the unknown.

  6. #21
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    Matthew: I asked WHICH woods are you planing. You answered end grain,which does not tell me which woods you are planing.

    As mentioned,A2 should be made to uniform standards. The alloy recipe for different steels is a standard thing. That said,I have always found Chinese HSS milling cutters to be more brittle,and harder than USA ones. I do not know why that is. It could be that they ARE deviating from the standard recipes for HSS,or it could be that their heat treating practices are different from ours. I can't say. But,metals made in USA should be uniform.

    Without being there and observing your sharpening angles and the quality of the edges you are making and how you use a bench grinder Matthew,and also your working practices,and what woods you are planing,it is impossible to diagnose why you are having problems. The only thing I can recommend from this distance,is for you to increase your sharpening angles.

  7. #22
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    I use several outside heat treating sources and also have a heat treat furnace in my machine/tool shop at my plant. Though the steel manufacturer's guidelines are very consistent, actual processing may not be. HT furnaces can be batch or continuous. Controls and thermocouples may be at either extreme of calibration (either done or in need), atmosphere type can be different, with some simply using a tool wrap. Removal from heat source is another variability. Finally, what are the final test methods to assure the end product has met specifications?
    If the thunder don't get you, the lightning will.

  8. #23
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    Here are the properties for A2 for those interested.

    http://www.steelexpress.co.uk/toolst...roperties.html

  9. #24
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    Agreed,Ton,. I mentioned that in my post about Chinese HSS. Something is different!

  10. #25
    They forgot to mention one thing Lonnie, you really should protect A2 against oxidation during the heat treatment. Either with a wrap of stainless steel foil or under protective atmosphere.

    Here is a diagram from Uddeholm.

    Uddeholm.jpg

    Arne is O1 steel, Rigor is A2 steel. The Vanadis and Vancron steels are powder metal steels. The others are conventional high alloyed kinds of steel. There is something interesting in this diagram. You can see how, within in group of steels, they can optimise for toughness or for resistance to abrassion. For example Calmax is very tough but not very abrassion resistant. In a chisel for chopping you want more toughness, in a plane more abrassion resistance. You also want good grindability for easy sharpening. But very good grindability goes hand in hand with low resistance against abrassion.

    Now, when you look at the powdered metal steels, you see better toughness AND better abrassion resistance then the conventional steels. But within the group of PM steels you still see tougher steels and more abrassion resistant steels. The PM process improves both because of the smaller grain size. It is also relatively easier to grind. But O1 is still easier to grind then the PM steels. BTW, PMV-11 is not in this list, so we can't compare it to the other steels. But it probably has some of the good properties of the PM steels too.

    You can also see in this diagram that A2 is less tough then O1, especially less resistant against chipping. Increasing the grinding angle gives more support to the individual steel grains so it doesn't chip anymore. But a higher sharpening angle reduces its sharpness.

    When you look at one steel for example A2 and look how it behaves at different tempering temperatures, you will see that in a harder state (higher tempering temperature) it will be more abrassion resistant but less tough. And the other way around.

    In steel there really is no magic. Everything is a compromise. Well, maybe the PM process is a bit magical.

  11. #26
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    Quote Originally Posted by Derek Cohen View Post
    I have minimal knowledge of metallurgy, so bear with my feable reasoning.

    First off, are there different qualities of A2? Steel should be made to a recipe, and I gather that A2 steel has 5% chromium to increase wear resistance. By comparison, stainless steel has 10.5% chromium. Adding more or less carbon, chromium, moly and vanadium will affect steel properties differently. Now if all steel manufacturers used the same formula for A2, we could rule out one variable. So the first question is whether all make A2 steel the same way, and that we may expect this area to be uniform?

    The second issue is how the steel is hardened and tempered. Is this also to a recipe? Can we expect the A2 steel from LV to be the same as LN and anyone else?

    It is only at this point that we may evaluate bevel angles, since increasing a bevel angle may disguise inadequacies/differences in a steel.

    Even if steels are prepared the same way, there are still rogue blades with brittle edges. Brittle is what leads to chipping. Indeed any chipping is a result of the edge lacking elasticity (tensile modulus), that is, it is too rigid. Powdered steels, such as PM-V11, are engineered to offer a finer grain structure along with -greater tensile modulus, which should (and does in my tests) offer greater resistance to chipping when hammering chisel edges into hardwood. PM-V11 may also be more safely used at lower bevel angles (as low as 20 degrees).

    It seems that there is more at work than fine grain structure alone, however, since simple carbon steel alone is not that wear or impact resistant. However it is more likely to roll than chip, unless the edge is brittle (from grinding or heat treatment). That is when one adds chromium to beef it up, and it turns into A2 or M2, etc.

    So before we start blaming A2, we need to know whether all A2 is expected to be the same - because if it is not, then we need to look at reliability factors, that is, from whom the steel is likely to do as promised.

    Anyone answer these questions?

    Regards from Perth

    Derek
    Derek,

    You bring up good points, I have always wondered this myself. Aside from the composition (ingredients) I believe it matters who makes the cake, even with the same recipe. I don't know if people selling blades actually have their own foundry. As something to compare, the screen on a Sony hi end TV is made by the same manufacturer that makes the one on a Daewoo more economical TV, likely with the same process, they just pick the top X% for Sony. By the same token, Intel never tries to make slow processors, they are all meant to be the fastest, except some don't meet the spec and they are clocked slower.

    /p

  12. #27
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    Can the way way the metal recipes are mixed have a roll is how the final product behaves? Even if the quantities of ingredients are identical from one makers A2 mixture to anothers, but they way they mix or produce the final product could vary...

    I am thinking along the lines of baking... I could mix a cup of flour with 1/4 cup of butter along with sugar etc. If I did it with hard butter out of the fridge, softened butter off the counter or melted butter off the stove, or reguar sugar granules vs powdered sugar, or rock salt vs finer salt granules, etc etc... All of those recipes may use the same quantities of the same ingredients, but guranteed the results will vary huge...

    Could it be the same for steels?

  13. #28
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    Pedro haha! I think we had the same thought at the same time...

  14. #29
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    Quote Originally Posted by Kees Heiden View Post
    They forgot to mention one thing Lonnie, you really should protect A2 against oxidation during the heat treatment. Either with a wrap of stainless steel foil or under protective atmosphere.
    Kees,

    Please see my post 17 about the variability of processing. Tool wrap will work, but it needs to be at least double crimped with no voids. Protective atmosphere is always best, but keep in mind there is also variation in the gases. Finally, differences will occur in the HT furnace itself: either batch or continuous belt, with batch being the easiest to control concentration of atmosphere and the belt potentially subject to atmosphere lift, depending upon the style of furnace construction (straight through, hump back, etc.). My point is, for example, you can process a piece of Carpenter Tool steel, A2 labeled, and it can vary significantly from one processor to another.

    Finally, when I hear of chipping issues, my first thoughts are problems more with the drawing portion of the process (at least in my industry). Double finally, there is no black magic in powder metallurgy-we are 300% scientific and replicable (and that depends upon standing on your left foot, with your right leg bent backwards at the knee, your tongue sticking out, with your head tilted exactly 17 degrees to the right, squinting cross-eyed and holding your breath-do that everytime and the results will be identical).
    If the thunder don't get you, the lightning will.

  15. #30
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    I have to use high temp(there are 2 types) of stainless wrap,carefully double crimped as Tony mentioned. I also usually include a postage stamp size piece of brown paper(no clay).

    You have to be very careful about how much paper you put into the stainless envelope,and it varies with the amount of air still in the wrapper. If you use too much,the paper will blow out the stainless steel when it burns up,ruining the part.

    Of course,the object is to burn up the oxygen in the wrapper because A2 52100,D2,and the other air hardening steels will badly decarb if you don't protect them from the air.

    If at al possible,I squeeze all the joints of the wrapper in a smooth jawed machinist's vise,re fold them over on themselves,and re squeeze. I have had good results. I have hardened quite a few punches and dies,knife blades,and plane irons that I have made from A2. I use A2 on punches and dies because I want them to last through many thousands of cycles of punching out plastic and paper(photographs) for my wife's jewelry making business. Some have lasted 25 years.
    Last edited by george wilson; 05-14-2015 at 12:33 PM.

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