Would 1/4" thick 10" blade be stronger of forged vs stock removal?

deltablade · Jun 5, 2015

I would appreciate comments on whether a 10" blade of 1/4 carbon steel would be noticeably stronger if forged rather than made by stock removal?

Bigfattyt · Jun 5, 2015

No. Geometry, heat treat and temper, and steel composition matters.

There is nothing inherently stronger about forging.

Modern steel is so technologically advanced, as long as you get a good billet, and pick the right geometry and heat treat, forging adds nothing, except the artristry.

Hand forged knives are lovely. They take skill.

But so does a stock removal blade.

A well made and we'll finished stock removal blade would be indistinguishable from a forged blade with the same level of fit and finish and geometry/specs.

Performance wise, you would not know the difference.

If you are using steel with impurities, like black iron sand, or smelting your own ore for the steel, forging, and folding help homogenize and purify the steel.

ocnLogan · Jun 5, 2015

Shouldn't be, unless the metal had inclusions in the stock to begin with (where theoretically forging would smash out the air bubbles, etc).

The resulting strength/toughness will likely depend more on the quality of the heat treat and overall blade profiles than anything else.

I could be way off though, as I'm no expert on forging vs stock removal. The above is my guess though.

I'm interested to see what the experts say.

Cobalt · Jun 5, 2015

There should be very little difference between both steels if you start out with quality steel. However, if you have no control over the steels you receive(especially from China/asia) and/or you don't/can't test to find voids or inclusions within the steel, then forging removes that unknown.

bodog · Jun 5, 2015

Are we talking about regular straight-ish blades or blades with any kind of curve, like a kukhri or some kind of Persian style blade or some kind of exaggerated trailing point? If we're talking about the latter, then I'd say forged because you can keep the grain running in line with the curves of the blade.

Jens Schuetz · Jun 5, 2015

bodog said:
Are we talking about regular straight-ish blades or blades with any kind of curve, like a kukhri or some kind of Persian style blade or some kind of exaggerated trailing point? If we're talking about the latter, then I'd say forged because you can keep the grain running in line with the curves of the blade.

Are grains that big and elongated?

bodog · Jun 6, 2015

https://www.google.com/url?sa=t&sou...VAEY1lLsh1ufODPog&sig2=-u8IoqlXRzzoke64Jg8tBw

http://www.jobshop.com/techinfo/papers/forginggrain.shtml

A kris type knife is a pretty obvious example of where forging over stock removal should be utilized. The reason forging a kris is beneficial is the same reason forging any curved blade would be beneficial. Not to say it can't be done with stock removal, but forging is better for certain applications. There are whole industries dedicated to this. Industries don't form out of thin air and without good reason.

Traditional Indonesian kris:

Kukri:

Persian dagger:

All of those examples would benefit from having the grain follow the curve for structural strength. Production companies use high shock/ high lateral strength steels that try to make up for the inherent weakness of stock removal. When you forge those same steels then you will see an increase in strength due to the shaping of the grain flow within the blade.

Good luck finding someone who forges 3V, though.

http://www.bladeforums.com/forums/s...-failure-on-8mm-thick-Condor-Heavy-Duty-Kukri!

Now obviously there's some other stuff going on with that blade, but take a look at where it snapped. It's right where the heavy impact meets the wrong grain pattern. In that case I don't think forging would've helped much because I think they blew the heat treat but it shows where the real weakness is in that kind of blade and how forging would reduce the weakness.

And another one, note that it's in the same location, right where the grain should start to follow the curve but doesn't.

Cobalt · Jun 6, 2015

Bodog, there is some more bad going on with that last knife, lol.

Anyway, I agree with what you say and I wonder how many companies even consider steel grain direction when they do stock removal. If they cut out their basic shapes with grain lengthwise but to tip or if they cut it transverse, spine to edge. This will also explain a lot of fractures. Still, properly manufactured, a stock removal blade will be easily as strong if done right. Which brings us to CPM, which has no grain direction and is like particle board(in idea not strength). But if you want real strong forged, then you go folded like this. Tripple folded 15 times for 1 million layers.

Jens Schuetz · Jun 6, 2015

bodog said:

Thank you bodog for this picture and the other information. Pretty impressive how the grain flows there.
Now I'm wondering how an unforged piece of the same shape would look like when etched after heat treatment.
Would there be no long grain at all, completely random grain, grain all in one direction only or would it follow the shape of how the heat from heat treatment penetrates the piece?
I'll Google myself too.

Edit:
Pretty much all in one direction. How does it happen? Maybe they form when the stock is being rolled flat?
When buying rolled stock can I assume the grain is flowing lengthwise or do suppliers cut the pieces randomly?

deltablade · Jun 6, 2015

A straight blade like maybe the 8" bark river gunny in A2 steel

bodog said:
Are we talking about regular straight-ish blades or blades with any kind of curve, like a kukhri or some kind of Persian style blade or some kind of exaggerated trailing point? If we're talking about the latter, then I'd say forged because you can keep the grain running in line with the curves of the blade.

RevDevil · Jun 6, 2015

Let's get the multipost issue under control.

Camber · Jun 6, 2015

Forging damages the steel. That damage has to be undone through normalization cycles to return the steel grain to a refined state.

Ask any ABS guy why they normalize after forging and if they would ever forgo that step.

What forging really allows for is a way to make much more elaborate shapes without grinding / cutting away a lot of steel.

At the end of the day, if both heat treated correctly there shouldn't be any difference in the quality of the steel itself between something forged and somethign stock removal.

The CPM process also doesn't inherently make a steel better...it is in it's most basic sense for high carbide steels as it creates a more uniform distribution of the carbides (and thus eliminates clumping that can weaken the structure). In other words, it's not a process to make steels better perse so much as a process to allow certain types of steels to actually be made with consistent quality. Steels like 5160, AEB-L are not CPM'd and not because they are inferior, but because they wouldnt' be significantly improved by the CPM process. They already have small well distributed structure.

bodog · Jun 6, 2015

RevDevil said:
Let's get the multipost issue under control.

Thank you, switching between tabs sometimes resets things and as I upload other pictures and whatnot I don't want to have to keep retyping and reposting those images. Looks much better now.

Camber said:
Forging damages the steel. That damage has to be undone through normalization cycles to return the steel grain to a refined state.

Ask any ABS guy why they normalize after forging and if they would ever forgo that step.

What forging really allows for is a way to make much more elaborate shapes without grinding / cutting away a lot of steel.

At the end of the day, if both heat treated correctly there shouldn't be any difference in the quality of the steel itself between something forged and somethign stock removal.

The CPM process also doesn't inherently make a steel better...it is in it's most basic sense for high carbide steels as it creates a more uniform distribution of the carbides (and thus eliminates clumping that can weaken the structure). In other words, it's not a process to make steels better perse so much as a process to allow certain types of steels to actually be made with consistent quality. Steels like 5160, AEB-L are not CPM'd and not because they are inferior, but because they wouldnt' be significantly improved by the CPM process. They already have small well distributed structure.

They normalize the steel because it's a step in the process, not because the steel is damaged in a way that can't be undone. The grain pattern is still an issue and is well known. If you don't want to normalize and don't care about grain flow patterns, then stock removal is the way to go as its fewer steps and the final product will be acceptable, to answer deltablade's question. If you have a blade shape with which you need strength running in an odd, curvy pattern, then forging is really the only way to go. Argue if you want but there's plenty of science to back it up. And the grain is still there regardless of carbide volume, so the CPM process is a little irrelevant. You can also say what you want about proper heat treatment and whatnot, but if it was really that simple then the different forging techniques used in all manner of steel production would be obsolete and that's definitely not the case. Most knives you see are made without a need to worry about which way the grain flow runs (aside from butt to tip) so stock removal is fine with today's quality steels as long as it's rolled out correctly, which most knife sreels are rolled with the grain running lengthwise. But there is absolutely a need to think about grain structure, grain flow, and strength in at least somewhat complex shapes you may see in the knife world. It's not about inclusions so much anymore as it is about bringing the best out of a given steel for specific applications where stock removal would be less than ideal, such as the blade shapes I posted earlier.

Actually, when I discussed this with Bailey Bradshaw (ABS master smith) he stated that he thought that there probably were some small benefits to be gained from forging 3V. Here are his comments on the possible improvements that forging 3V could have. In the first quote he is talking about a 3V hunter that he forged. Notice that in one example in the second quote he clearly emphasizes the words could and might.

Quote(Bailey Bradshaw):
I will say that this blade was more difficult to grind and finish at the same hardness than any of the hundreds of other 3-V blades I have made.
Quote:
If I had to guess at the forging improving the steel in any way, it would be twofold. One would be aligning the grain flow with the blade's shape. Another MIGHT be the increased time at sub critical heat COULD have aided in forming more carbide structure. 3-V is an air hardening steel, and requires 30 min. or more soak time at 1975 degrees. More soak time on these steels usually equates to higher hardness due to more carbide formation. It's the only explanation I can come up with to give reason for the difficulty in grinding and finishing.

Not my discussion and it's on another forum so I won't crosspost the link.

Grain flow is one of the major benefits cited for the use of forgings. Unfortunately, there are misconceptions on the topic, which include the underlying causes of grain flow, the benefits that can be accrued from grain flow and how to achieve an optimum grain flow. In the best case, grain flow results in a delighted customer and aforging that thrives in a critical service application.

To begin, let us provide a definition of grain flow in forgings. Grain flow is a directional orientation of metal grains and any inclusions that have been deformed by forging. Individual grains are elongated in the direction of the metal flow or plastic deformation. More importantly, nonmetallic inclusions, particles and other imperfections inherited from the casting process are elongated in the direction of grain flow. It should be noted that grain flow occurs to some degree in all metal-forming processes, not just forging...

Effect on Mechanical Properties
The important implication about grain flow is that some mechanical properties vary with respect to orientation relative to grain flow. This fact is one of the major benefits ascribed to forgings. This variation in mechanical properties can be exploited so that the actual product has superior properties in a critical direction relative to those expected from the alloy composition itself.

However, we should be clear that not all of the mechanical properties will vary significantly with the grain flow. For example, strength and hardness are primarily controlled by the alloy chemistry and the heat treatment that is given to the forging. Grain flow will not have a major effect on the strength or the hardness of the alloy. In contrast, desirable properties associated with retarding crack propagation can see significant differences depending on the grain flow and the direction of the moving crack. So, properties like fatigue strength, impact toughness and ductility, which are measures of a materials resistance to cracking (measured after fracture), can be significantly improved if the crack propagation direction and the grain flow are properly aligned. The optimum alignment occurs when the maximum principal stress (perpendicular to a potential crack or fracture) is aligned with the grain-flow lines...

Content for this paper was primarily developed by Scientific Forming Technologies Corporation in partnership with SCRA Applied R&D and FIA. The material was initially developed as a Forging Design Seminar under the FAST program, a multi-year, industry cost-shared program sponsored by the Defense Supply Center Philadelphia and Defense Logistics Agency Research and Development.

http://www.forgemag.com/articles/84265-grain-flow-in-forgings---the-basics

So to sum it up, if you want the best process for a knife where grain flow patterns should be considered, then go with forged steel, as long as the guy who's doing the forging knows what he's doing. If grain flow patterns are not a consideration or the guy doesn't know what he's doing or is completely unfamiliar with working a certain steel you want used, then save your money and go with stock removal.

Joshua J. · Jun 6, 2015

All the answers you could want are probably in this article. http://cashenblades.com/images/articles/lowdown.html

Most of the benefits of forging are already present in anything but cast barstock, since virtually all barstock is rolled at the factory.
From the article:

It somewhat smacks of hubris to take a piece of steel that has already been reduced from feet to fractions of an inch in thickness, hammer a bevel down one side and then proudly claim we have made the steel superior by our forging.

Cobalt · Jun 6, 2015

Joshua J. said:
All the answers you could want are probably in this article. http://cashenblades.com/images/articles/lowdown.html

Most of the benefits of forging are already present in anything but cast barstock, since virtually all barstock is rolled at the factory.
From the article:

Yup, accurate as can be. Forging takes the guess out of crap steel and makes it better. If your steel is excellent to begin with no need.

bodog · Jun 6, 2015

Joshua J. said:
All the answers you could want are probably in this article. http://cashenblades.com/images/articles/lowdown.html

Most of the benefits of forging are already present in anything but cast barstock, since virtually all barstock is rolled at the factory.
From the article:

What's funny is that the article is simply saying crap like edge packing is nonsense and that forging a blade to shape has a tangible effect on "complex" shapes where crack reduction is necessary, basically anything more than a straight blade with no curves or shapes can be better forged to shape. He says that basically everything about forging is just extra work, except for when grain flow is a consideration.
I guess you missed that part and want to say that forging has faded away from usefulness but the guy writing the article says he still prefers forging. I presented the same information as Cashen in his article, yet you're using his article to disprove something he didn't even try to disprove in his article, and as a matter of fact, he said it is undeniable. if you're going to have a "complex" blade shape, forging is good. If not, it's not worth the cost. I've said that multiple times and the article you posted basically says the same. Are you arguing against the article you yourself presented?

Going against the grain

One undeniable aspect of forging things to shape, that we can get out of the way immediately, deals with the directional structure of steel from the aforementioned milling process. This condition is the result of the elongation of impurities, voids and inclusions in the direction of the rolling operation resulting in a wood grain type effect, such that the material will have slightly different properties in one direction than in another.

In order to avoid a very common confusion, it must be heavily stressed that the term grain in this case has nothing to do with the crystalline structure of the metal, such as an austenite grain, but instead refers to this directional property, as in going against the grain, and is not affected by annealing and other heat treatments. The condition where a property of a material is different in one direction than it is in another is known as anisotropy, and we will examine it again later in this discussion.

The quickest and easiest way to demonstrate how forging can affect the properties of a tool via this directional nature is in the classic crank shaft example

That's exactly what I said and in fact, used the same example, a crank shaft.

And I guess this section of one of my other posts means nothing?

Content for this paper was primarily developed by Scientific Forming Technologies Corporation in partnership with SCRA Applied R&D and FIA. The material was initially developed as a Forging Design Seminar under the FAST program, a multi-year, industry cost-shared program sponsored by the Defense Supply Center Philadelphia and Defense Logistics Agency Research and Development.

In other words, the Department of Defense and military research and development groups say this is a real thing and should be accounted for.

Gaston444 · Jun 6, 2015

Randall say they forge their blades, does that mean they forge on top of barstock already rolled, or that they work from cast stock?

They are also just about the only ones to forge 440 stainless steel, because they have the industrial size machine to do it, which almost all custom makers can't afford due to the extra difficulty of forging stainless, particularly this one.

I also heard they used to go to Army bases and do live demonstrations, putting a forged blade in a wrench, and bend it in a half circle 180° without breakage...

Gaston

Cobalt · Jun 6, 2015

Gaston444 said:
Randall say they forge their blades, does that mean they forge on top of barstock already rolled, or that they work from cast stock?

They are also just about the only ones to forge 440 stainless steel, because they have the industrial size machine to do it, which almost all custom makers can't afford due to the extra difficulty of forging stainless, particularly this one.

I also heard they used to go to Army bases and do live demonstrations, putting a forged blade in a wrench, and bend it in a half circle 180° without breakage...

Gaston

Well then, there should be a video of it, right? I'd love to see that. I mean if anything has been done in the last 7 years it should likely be on video.

Freman Bloodglaive · Jun 6, 2015

We should give something a pass just because it's sponsored by the Defense Department?

Can anyone say F-22?

A crankshaft is a complex shape, modeled in three dimensions and subjected to a variety of loads.

A blade is not a complex shape, however curved it might be.

bodog · Jun 6, 2015

Freman Bloodglaive said:
We should give something a pass just because it's sponsored by the Defense Department?

Can anyone say F-22?

A crankshaft is a complex shape, modeled in three dimensions and subjected to a variety of loads.

A blade is not a complex shape, however curved it might be.

That's why I quote it when I say complex. It's relative, but no less an important consideration. If you want to argue with a lot of people who know more than you and I ever will, call them up and do it. Won't affect me either way.