Evaluating Forge Quality

[Cookie4Monstah]

Greetings everyone,

 

I would like to ask you how to properly examine the forge quality of a blade? When blades are out of polish kizu can be hard to see with the eye. I would like to expand on this topic by asking what kind of electron microscopes can be used to really get a look at a blade. I find these artifacts to be much more intriguing than exotic microscopic organisms (upon closer examination). Not every blade is a good forge thus good forges are worth holding onto. I do love to see blades in fresh polish and pristine shirasaya though. More on that later.

 

Sincerely,

Khalid

[b.hennick]

I think that the resolution of the electron microscope will be too high for you to get much relevant information. The most that I use is about 40X magnification and this is just to look at small areas of interest. 

[Cookie4Monstah]

2 hours ago, b.hennick said:

I think that the resolution of the electron microscope will be too high for you to get much relevant information. The most that I use is about 40X magnification and this is just to look at small areas of interest. 

Hello,

 

I was thinking of scanning and doing digital image overlays. That way the entire blade can be mapped from both sides. If I can get this to work I would be more than happy to share with you my findings. The idea is to get a digital map of the blade if you will and to be able to save it digitally for reference.

[kissakai]

Looking forward to your images

 

[ROKUJURO]

Khalid,

did you read about how an electron microscope works? It seems you need to make very small very thin samples that fit into the very small vacuum chamber of the device, if I am correctly informed.  

Perhaps not all collectors all curious enough to have their blades cut up in tiny sections.....

[1kinko]

A scanning EM allows for larger objects and has all the resolution needed.

[Ford Hallam]

I would suggest that first we'd need to agree on what criteria constitute a good forge.

A 'perfect' forge weld in logical extreme definition might be one that is absolutely without any gaps or slag inclusions, and thus completely lacking on any definition regarding hada/grain. The microscopic slag inclusions do provide addition corrosion protection though.

In the same vein schools are noted for very different degrees of refinement in terms of exactly the 'perfection' of the forge welds. The appreciation of these varying qualities is, of course, subjective. 

 

 

 

[OceanoNox]

TEM: Transmission Electron Microscope, requires thin slices (below one micrometer) of samples usually ~3 mm in diameter. Relevant for dislocation, dislocation structure, etc. analysis, but difficult to scale and usually large scatter when trying to do quantitative analysis. The resolution can go to the nanometer.

SEM: Scanning Electron Microscope, can analyze anything that transmits electrons (and even if not, covering the sample in metallic ion works). Newer ones have very high resolution at high magnification (x20,000). Also benefits from good depth of field.

 

Even though SEM have bigger chambers now (enough to put both hands), unless the sample is small, cutting will be necessary. Prof. Morito has done some work with SEM with an EBSD camera (to obtain the grain orientation) calculating the history of the microstructure of Japanese swords, to evaluate the change in grain size and microstructure at the time of the quench (basically how fine the austenite was prior to quenching and tempering, simply from analyzing the martensite in the edge).

 

Back to forge quality, I was just reading 武芸風俗姿 (I forgot the year). I cannot judge at all because I do not cut and I have not handle many swords, but the author maintains that small "kizu" is not an issue for blades, as long as these are not structural flaws, and rather show high hardness. From a purely metallurgical point of view, no segregation, microstructure uniformity, low amount of weakening inclusions, etc. would be indicative of a good process and good mechanical performance of the blade. Ultimately, in terms of hamon, and this has been stated by others who do tameshigiri, it would mean a suguha.

[DoTanuki yokai]

Wich one is the better Suguha ? Nie Deki with a wide Hamon or a narrow Nioi Deki one ? 

And then one would ask can the Electron Microscope tell wich Hataraki improve my sword or not ?

I think all this questions were answered in the past by actual use and they came to the conclusions that led to what we today desire in Nihonto because that is what made them good weapons on the battlefield.

[OceanoNox]

I remember that the interest in suguha is that there would be few stress concentrators, but I do not think the discussion went as far as differentiating nie and nioi, or discussing hataraki. Not being an expert, I am likely mistaken, but was it the shinto that had wide and wild hamon that ended up being brittle swords? So perhaps a not overly wide hamon is better in terms of properties.

At any rate, I feel like I am going back to the thread about ideal swords (in terms of mechanical properties, beauty, or use for fighting?).

[mas4t0]

What you're seeking is termed Non-Destructive Testing (NDT).

 

X-rays and ultrasound scans will tell you more about the blade, as they can show delaminations and voids below the surface.

 

A good quality portable ultrasound scanner can be had for a few thousand dollars.