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Joshua MacDonald




Location: Chiba City, Japan
Joined: 16 Nov 2006

Posts: 10

PostPosted: Mon 20 Nov, 2006 9:10 pm    Post subject: side effects of heat-treatment?         Reply with quote

I just have a small query about the forging of arms and armour.

Upon quenching the sword ,lets say, is there a possibility of warping the piece.

Of course the properties change (hard, brittle, etc.), but I am asking a topological change may occur.

Thanks in advance.


Josh
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Torsten F.H. Wilke




Location: Irvine Spectrum, CA
Joined: 01 Jul 2006

Posts: 250

PostPosted: Mon 20 Nov, 2006 11:38 pm    Post subject:         Reply with quote

Yes, it is possible with thin materials at higher temps required to achieve modern high-strength states. Lower carbon alloys as used in period really would not have seen these higher temps, so they would have had a low likely-hood of deforming. Basically, there were probably no worries with properly tempered period armour or arms. Quarter inch thickness is substantial enough not to be bothered by warping in practically all cases, and that is the approx. thickness of most swords. An 18 guage armour made from 4130 (standard chro-molly) heat treated to the approx. 200 ksi and above range might encounter problems with slight deformation, if a high-temp heat-treating jig was not used. I might be slightly off on some of the numbers, but the gist is correct. Hope that helped some... Happy
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Peter Johnsson
Industry Professional



Location: Storvreta, Sweden
Joined: 27 Aug 2003
Reading list: 1 book

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PostPosted: Tue 21 Nov, 2006 1:05 am    Post subject:         Reply with quote

Small variations in grain structure, uneven surface finish and uneven heating of the steel prior to quenching will very easily lead to warping, distortion or even cracking.
Whatever work has been done to the piece before heat treat will have an effect on final outcome. Even cold work like filing can build stress in the surface of the steel that might provoke bending in heat treat if not normalized properly.
Normalization is absolutely critical for good results.
Even then, a long thin object like a swordblade very easily takes a set in heat treat. What is really very minimal in a short blade like a knife will be multiplied many times in a long sword blade.
There will normally be some slight straightening to do each and every time after heat treat. Sometimes it is very minute, sometimes more severe.
I do not think this is any different today than it was in ancient times. Even if you have blades that are partly made of iron that do not take hardness in a quench, you can still get warpge in the stel present.
When you heat treat swordblades, you quickly learn techniques to straighten.

An even surface all over the blade and an exact edge thickness on both sides from base to point will help minimize warpage. It is still paramount to apply heat carefully and evenly.

Also with armour there can be distortion.
You can use the rivet holes in the plate to fasten fixtures to minimize warpage. I do not make armour these days, so others might provide more info here.
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Joshua MacDonald




Location: Chiba City, Japan
Joined: 16 Nov 2006

Posts: 10

PostPosted: Tue 21 Nov, 2006 8:55 pm    Post subject:         Reply with quote

Very intresting.

Thanks for the information.

josh
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