Tempering/Quench lines

archer · 15th March 2009, 09:58 PM

A while back Alex mentioned a blanched area on a blade caused by quenching. What causes black or darkened quench lines? While we're at it note that the third blade shows a V chevron pointing towards the blade tip. The two upper blades show the first quench line dark and pointing toward the hilts then each show two more quenches with the V changing directions. What is that all about besides I have to much time on my hands. lighting was bad but i think you'll see what I mean.

Thanks, Steve

G. McCormack · 16th March 2009, 03:01 AM

Steel is made up of crystals, and its crystal microstructure is dependent on things like how it was worked, and what temperatures it was heated up to and cooled down from- and at what rates.
When a bladesmith quenches a carbon containing steel blade from above a specific temperature into oil or water, certain microstructures are formed. Different microstructures form because of a number of factors, including the amount of carbon, the temperature before quenching, and the rate of cooling.
These different microstructures look different when etched, and that is the reason parts of your blades are darker than others.

archer · 16th March 2009, 06:29 AM

Since the top two blades are probably from the same general area.
I can see I was comparing apples and pears. Your explanation, makes sense to Me. now that i can step back and see why the different effects occurred. Thanks you,
Steve

G. McCormack · 19th March 2009, 05:50 AM

nice looking blades, btw! ;-)

ausjulius · 19th March 2009, 06:00 AM

Quote:

Originally Posted by archer

A while back Alex mentioned a blanched area on a blade caused by quenching. What causes black or darkened quench lines? While we're at it note that the third blade shows a V chevron pointing towards the blade tip. The two upper blades show the first quench line dark and pointing toward the hilts then each show two more quenches with the V changing directions. What is that all about besides I have to much time on my hands. lighting was bad but i think you'll see what I mean.

Thanks, Steve

it is differential hardening,
the tips on the first two are both harder than the blade area and then again softer at the hilt.

the last knife seems to be only harder in the main part of the blade than the hilt.

it is interesting to see this obveously the arab who made them intended them to be used, id say most later ones would be all like the lower 3rd knife..
no doubt the top 2 were made at a time when these were used frequently as weapons..

15th March 2009, 09:58 PM	#1
archer Member Join Date: Mar 2005 Posts: 373	Tempering/Quench lines A while back Alex mentioned a blanched area on a blade caused by quenching. What causes black or darkened quench lines? While we're at it note that the third blade shows a V chevron pointing towards the blade tip. The two upper blades show the first quench line dark and pointing toward the hilts then each show two more quenches with the V changing directions. What is that all about besides I have to much time on my hands. lighting was bad but i think you'll see what I mean. Thanks, Steve Attached Images

16th March 2009, 06:29 AM	#3
archer Member Join Date: Mar 2005 Posts: 373	Responce Since the top two blades are probably from the same general area. I can see I was comparing apples and pears. Your explanation, makes sense to Me. now that i can step back and see why the different effects occurred. Thanks you, Steve

16th March 2009, 03:01 AM	#2
G. McCormack Member Join Date: Jul 2005 Location: Tallahassee, FL Posts: 131	Steel is made up of crystals, and its crystal microstructure is dependent on things like how it was worked, and what temperatures it was heated up to and cooled down from- and at what rates. When a bladesmith quenches a carbon containing steel blade from above a specific temperature into oil or water, certain microstructures are formed. Different microstructures form because of a number of factors, including the amount of carbon, the temperature before quenching, and the rate of cooling. These different microstructures look different when etched, and that is the reason parts of your blades are darker than others.

19th March 2009, 05:50 AM	#4
G. McCormack Member Join Date: Jul 2005 Location: Tallahassee, FL Posts: 131	nice looking blades, btw! ;-)