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So recently I was involved in a debate about steel, more precisely, modern carbon steels used in knife making.  This may seem like a bladesmithing topic but I think it applies better to general forging of modern carbon steel.  at any rate its a good study of material science. 

It started as I overheard some general conversation about forging a complicated knife shape vs stock removal to achieve the same shape.  the argument was that in a "modern carbon steel" it dosnt matter whether you forge the shape or mill or grind it away, it would achieve the same strength once it was properly heat treated.  this went against my general understanding of forging of parts, blades, or whatever.

my addition to the conversation was that, all things being equal, a forged shape would be stronger.  if two parts were made, one in a machine shop via stock removal, and one in a blacksmith shop via forging with minor finishing as required to achieve similar tolerances.  then both parts sent through the same heat treating process, the forged one inherently retains a more cohesive grain strength, making it stronger.  the reason for machining is keeping tighter tolerances and speed of manufacturing.

the argument back was that, when properly heat treated, original grain patterns do not affect finished strength, they are mostly reset.  and that the talk of grain strength was just a carryover in blacksmithing from the wrought iron days of very large grains where it mattered greatly how the grain was oriented.

now I don't discount that the difference may be minor, but I find it impossible to believe a forged shape isn't stronger.

 

 

 

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Look up a video of how steel stock is manufactured. You should have a different opinion by the end.

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This is a common misconception on the scale of blade making. If you're talking about making crank shafts forgings are stronger, not a lot but some. The real reason crank shafts are forged is it's about 50x faster and a less wasteful of steel. 

Do you know how that 5/16" x 2"  piece of O1 got to be that size? It was forged from a billet of tool steel weighing oh I don't know 100 tons? About a 4' x 4' x 12' steel ingot gets pinched off the continuous caster in the mill. It drops onto a table that manipulates it into the first set of rolls and it passes through roll forge after roll forge till it's a length of the above dimension steel + a margin to grind to exact dimension but by then it's been cut a hundred times or it'd be a miles long ribbon going a couple hundred miles an hour.

Go ahead grind it to shape and heat treat it. Nothing a mere human being can do to it with hammer and anvil or power hammer can make a significant difference. Frankly considering the difference in grain (crystallography) elongation between mill finished and as forged by a bladesmith, you actually have much better grain structure from the mill.

Proper heat treat helps reduce the grain growth (adverse crystal boundary junctions) CAUSED by the bladesmith.

Go ahead link us too all the articles written by bladesmiths saying otherwise. I love the guys but it's mostly puffery just like the Ford Chevy debate or one team over another.

Frosty The Lucky.

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9 hours ago, C-1ToolSteel said:

Look up a video of how steel stock is manufactured. You should have a different opinion by the end.

Yes seen them, and been in mills first hand.  unless im missing something, it only strengthens my thoughts on trying to retain the grain from the steel mill.  

Eh anyway im not a bladesmith, just curious.

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 its cheesy but answers my concerns...

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Now, there ARE some people who believe in something called packing. I'm not sure if it actually improves edge retention or not, but some people say it does. Sounds similar to cold rolling.

But as for regular forging, like Frosty said, when it has been worked from a 100 ton block, it doesn't make much of a difference to forge it the rest of the way. One of the worst arguments I have ever heard for why damascus is "the best" is that it is "more forged" than regular steel.

All that being said, I COULD be completely wrong, so do a good scientific test, and maybe this subject is worth revisiting.

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This argument has gone on since Material removal methods came on the scene and wrought iron was still a key player..When it had a section cut out of the side of a bar, it would peel off.. Not a great thing..  

While technically a  properly forged product will have an increase in ability to withstand pressure if it is applied across the grain structure (sideways)..   There are not a lot of people doing proper forgings..  I know I will catch fire for saying this..  I'm not saying there aren't a lot of great smiths or great products forged out there. What I'm saying is a lot of forgings now have disrupted grain flow..  I'm just as guilty since i don't work with Wrought iron enough anymore and get sloppy because modern steels can be worked all crazy like and still have a working product.. 

I go back to wrought iron and how it has to be forged, punched, cut, slotted etc, etc because of the inherent grain structure which is totally visible while being forged and if you go against that grain structure it will yell at you.. 

Most steels today are cast before rolling and if rolled will have a defined grain structure in the bar..(Casting will also setup a defined grain structure)  It's part of the process..  If forged properly it will keep that grain structure in a straight pattern. Straight  relative to the central grain structure.. 

If you have ever worked a large section of steel and have seen the inside portion stay where it is and the outside edge of the steel cup over the center.. Well this is creating a grain slip and will show a grain structure at the part between the fast moving and the slow moving materials like a glacier moving over the earth.. 

One of the key reasons the Japanese forged their blades the way they did is the materials were of poor quality..  The repeated welding and hammering refined the metal so it became a usable product with known qualities..  People are still doing it today with vintage type smelting furnaces.. The steel that comes out would be useless without refinement.. 

In the old days it was all about producing better steels for better weapons.. Wootz,etc, etc..  and then the largest change is when cast iron could be changed to steel. It made steel super cheap to produce.. 

One could argue the extra performance of correctly forged vs ground/stock removal would that performance ever be recognized physically by someone if it reaches that limit.. More than likely not..   I can say.. That it's only when items are pushed to the extreme that the margin of one vs the other might be realized..  

 

The extremes or in a laboratory environment where they can test the difference would be more than likely the only tell tale signs..

For all the Nin-gu I used to make I used to test everything to my body weight and intended purpose..  Everything only had the needed strength for it to work 100% for me.. Someone with bad technique or weighed more the item would fail..    I can tell you the items that were forged could be made smaller than the items that were machined..  

 

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