Chikuzen no Kuni-jū Yoshimasa Naginata grain structure.

[pt1093]

Due to poor packaging and handling, my newly purchased naginata was received missing approx. 1/8" of the tip.  After the initial bout of swearing, I decided to make the best of it and get some up close photos of the grain structure, see attached.  I was surprised to see a globular type grain.

[Larason2]

I'm sorry that happened to you, but thanks for sharing those fascinating pictures!

[John C]

2 hours ago, pt1093 said:

I was surprised to see a globular type grain.

Paul:

Sorry for your loss. But I do have some questions. Is the dark area under the bubbles a crack where rust had gotten in or just part of the softer, low-carbon metal? Also, are the bubbles a result of excessive heat during the heat treat?

John C.

[pt1093]

John,

  My guess is the dark areas seen are either early stress cracks that corroded over time, or they are the weld joint between the soft/ hard layers.  There is a noticeable seam on the spine that could indicate the later.  I too thought excessive heat, a point is harder to control.

[Baba Yaga]

The tip of what, Kissaki, or Nakago? Im assuming the Kissaki? Many swords were in fires, but that's another assumption? Could be a crack, can't tell with photos. 

The Kissaki tells all and the most assuming. 

[pt1093]

[DoTanuki yokai]

Yea I would say the blade already had a crack and that’s the reason it broke at this place while transport. 

I thought a much bigger piece was broken from seeing the first pictures :D

 Grain is always kind of globular it’s just hard to see when it is finer ? 
Like sand = bad 

like fine powder = good

 

A blades tip is always the easiest to overheat when not careful enough, so it’s less of a surprise  that the grain is so large there. 

Almost looks like fresh tamahagane again