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The Newbies Arena Are you new to knife making? Here is all the help you will need. |
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#1
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Grain flow and forging.
![]() I keep seeing a lot of images like this, with very little metallurgical explanations and claims that a forged item is superior due to it's "true grain flow". Does this have any packing in reality or is it just a myth? |
#2
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I understand what they are saying in the pictures but, while what they show is accurate, I don't think that has much to do with knife making. A knife blade generally does not have a complex cross section, it is essentially a straight metal bar. While it is true about the grain being disturbed by the grinding and shaping of the bar stock into a blade by stock removal the grain adjusts and aligns itself during the heat treat process. The grain alters any time the steel is raised to a high enough temperature whether you hit it with a hammer or not.
In short, I think a fair number of knife makers these days would tell you that a properly heat treated stock removal knife will perform pretty much identically to an identical forged blade. Personally, I think that a forged blade made by someone who truly understands heat control will have a slight advantage over a comparable stock removal blade but that will be because the stock removal blade is more likely to be treated in an oven where the finesse I referred to cannot be easily accomplished. But then, that finesse isn't often accomplished by anyone forging either...not that they don't try. In short, the difference, if any, in the grain of a forged blade or a stock removal blade will be due to the heat treat process and not from the act of forging per se... |
#3
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Well, a lot of hidden tang knives might have quite aggressive shoulders between the blade and the tang, it could matter then, maybe, just a little bit? Or not.
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#4
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Don't equate the "no grain flow" of the first example with no grain. There is grain. It's just random because it hasn't been hot rolled to give the grain direction. I'm just starting to get my head around the concept but there is a certain type of grain that is set by rolling it at the mill and then there is grain that forms and reforms along the intercrystal boundaries in random directions. Kevin Cashen wrote up something about grain not too long ago that explained it much better than I can. I'm just not sure that it was on this board. Try googling something like steel grain + Kevin Cashen and see what you can come up with.
Doug __________________ If you're not making mistakes then you're not trying hard enough |
#5
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Working in sheet metal and heavier metal fabrication I can say with certainty the the rolled grain at the mill does cause grain flow in some materials. Bend a piece of cold rolled 4140 with the grain and you will get long cracks if you use too small of a bend radius. T4 tempered aluminum will tend to crack too. Always tried to bend against the grain, T6 aluminum would almost always crack. The grain flow means nothing in a knife though as they do not get bent in the hardened state, notice the example shows a bent part that is bent against the grain. Do that in the opposite direction and even if the steel doesn't crack it will not be as strong as the other way.
Some types of brass do not bend well either and will crack when bent too far. It is easy to HT, just heat to around 450, just hot enough to burn a piece of pine rubbed up against it let cool and you've got about 2 to 3 hours to bend it before it hardens again, same for some aluminum tubing that cracks when you bend it. If you get steel tubing that cracks when you bend it send it back, they sent you the wrong stuff. |
#6
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IMHO, I would also suggest keeping a healthy bit of skepticism close at hand when getting into discussions about grain formation and forging. There is a lot of legend and lore wrapped up in such things and while some of it has a basis in reality, some is just wishful thinking.
I think that Ray identified the key issue - the quality of the final product has a lot more to do with the skill and knowledge of the maker rather than whether the blade was forged or not. -b __________________ -bill rankin |
#7
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with a Damascus blade...... there will be a VISIBLE grain of sorts.....
no matter what you do youll end up with the middle pic. other wise itll just look like one plain piece of steel, except on the spine. youll have to grind THROUGH the layers to expose the pattern/grain. now comes what ray said...... during heat treat, the individual grains of each layer will realign if the billet was forge welded properly. wootz steel..... someone else will have to chime in on that one. that stuff is still within the realm of "magic" for me. |
#8
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"Grain" I think has a lot to do with alloy. Wrought iron has a definite grain structure, will many modern steel alloys really don't. I've seen grain structure in some tool steels, and I believe one can manipulate it. High alloy steels and air hardening tool steels don't develop a grain flow that I'm aware of. It would be interesting to know if this is true.
As far as the whole forge vs stock removal. I've always held the opinion that a forged blade, done properly might perform slightly better, but there is so much that can go wrong during the forging process that for most makers a stock removal blade would perform better. |
#9
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At the time it is forged that section would have that 'grain flow' as described but there would also be considerable stress at that point because of the forging. That stress will be relieved during the heat treat process - the same process that will re-align all the grain in the blade. That's the same thing that will happen to a stock removal blade during heat treat. If the forged blade is stronger at that point it would be hard to say the difference was great.
All my blades are stub tang - little short 2" tangs, even on a 22" short sword thing I made. All stock removal. Never had one break at the tang or anywhere else except for one where the burl handle came apart. The sword especially has been tested by anybody that comes over here by slamming it into a stump and then twisting and bending the blade. This has been going on for 17 years and so far not the slightest separation of the handle from the tang and no complaint from the tang. My feeling is that if you have a failure at that point the cause is more likely to be poor heat treatment or poor construction technique than the method used to shape the blade ... |
#10
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I've had this discussion many times with many other makers.
I think JM nailed it. In the hands of a mastersmith, a forged blade likely has a small edge on performance potential (how small is debatable). However, in the hands of a mere mortal (most makers) a forged blade has many, MANY pitfalls and risks that can end in catastrophic failure. Even if such a blade does not fail, it is not likely any better than a stock removal blade of the exact same design by the same maker. I'd love to see a blind test done to explore this debate. Design a knife--simple, but specific. Have two different makers make two knives each. All four knives would be made to precise specifications with very precise material choices. Each maker makes the knife via forging and then via stock removal. One maker will be an experienced forger and the other a stock removalist. Then, have all four 'identical; knives tested by other makers who do not know which is which. I wonder how predictable the results would be. I wonder if each maker could avoid injecting his personally held bias into his work. __________________ Andy Garrett https://www.facebook.com/GarrettKnives?ref=hl Charter Member - Kansas Custom Knifemaker's Association www.kansasknives.org "Drawing your knife from its sheath and using it in the presence of others should be an event complete with oos, ahhs, and questions." |
#11
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Andrew I would also be interested to a see some test's done like that, but then again I think the debate would continue because what steel do you use? say these knives were made with 1084 and one way or the other proves better, but then what about other steels and stainless 440c then you have high end steels like s35vn. I think unless a HUGE number of tests were done and even with that the debate would find a way to continue. some steels are better for one thing than another and I think forging / stock removal would be prove to be the same, I don't forge my knives but I am sure some steels would be good to forge and others not so much.... how ever IF this test was done with a few different steels I would be interested to see the results
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#12
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Another valid question:
If the object is to have the finest grain structure possible after heat treating, then what difference does grain direction make? __________________ Andy Garrett https://www.facebook.com/GarrettKnives?ref=hl Charter Member - Kansas Custom Knifemaker's Association www.kansasknives.org "Drawing your knife from its sheath and using it in the presence of others should be an event complete with oos, ahhs, and questions." |
#13
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I agree dtec.
In the end, it preference. This is a journey and for many, forging is their chosen path. I see the appeal. I enjoy it myself on occasion. It's true what was said earlier too. Their is a great deal of mysticism and lore and most of all, pride involved here. Its no different than trying to debate with someone over who makes the best motorcycle, or what is the best handgun for defense. As you said, there are just too many variables to make a sweeping and definitive conclusion, but it could probably be determined in very specific tasks, with very specific steels, geometries, hardnesses, etc. Since this is the Newbies Arena, I will target my words for that audience: Choose the path(s) that appeals to you, and make the best knives you can make. They will be just fine. __________________ Andy Garrett https://www.facebook.com/GarrettKnives?ref=hl Charter Member - Kansas Custom Knifemaker's Association www.kansasknives.org "Drawing your knife from its sheath and using it in the presence of others should be an event complete with oos, ahhs, and questions." |
#14
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I agree, I started this whole hobby (and hopefully soon a good buissness) because it was something I really enjoyed, as most do, every one should keep true to what makes THEM happy...to me I enjoy knife making I don't look at it as being a job even when I am making blades to sell but (and maybe this is because I haven't done it much to learn enough) for me forging a knife is a lot of work and for me it turns it into a JOB at that point I am not enjoying it as much and I feel like I am doing ALOT of extrawork. that is why I don't do it. However another maker I meet with some times as he lives close is the exact opisate he forges every blade he makes and trust me we have had many conversations over wich is better and he was very surprised how well some of my blades perform... but he forges because he enjoys it he settles in and goes at it he enjoys the traditional aspect of forging knives...so again in my opinion every one should stay true to what they enjoy and what they think works...that's how we get so many different styles and so many different knives out there and I think variety and the enjoyment is what keeps this skill alive
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#15
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Try going to KnifeDogs.com and under heat treating look for a thread titled grain flow direction in O-1 and A-2. There's an interesting discussion there on this very same thing with a couple of entries from Kevin Cashen who tries to make this as simple as possible.
Doug __________________ If you're not making mistakes then you're not trying hard enough |
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bee, blade, brass, forged, forged blade, forging, grinding, hammer, heat, heat treat, hot, knife, knife blade, knife making, made, make, makers, making, metal, mill, photo, rolling, show, steel, stock removal |
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