Damascus steel

[Martyn]

Jason, very funny, but be careful, some novice might not realise you are pulling their leg and might think that they really should align their quench with a compass, or by the stars or something

I thought he was being perfectly serious. I thought it was something to do with carbide formation when the steel has been taken past non-magnetic and then quenched. I know some american smiths align thier forges etc in such a way - unless of course they are all wind up merchants.

 

[C_Claycomb]

Well I thought there could only be two reasons Jason would say he aligned his quench, and chose the one I reckoned was more flattering. I do hope he was joking!

There are so many things that affect the quality of a blade that to worry about the microscopically small difference that magnetic alignment might or might not make is silly. I would bet money that no one using a simple forge could possibly be consistent enough to tell one way or the other if such a thing made a difference. Exact temperature and time above critical, how fine the pre-quench grain was, the temperature of the quench oil, and the variability in steel, even of the same type from the same manufacturer, will all make so much more of a difference.

There is far more mileage in holding that a triple quench is better than a soak and single quench, or that a home freezer will promote martensite conversion. You can really get a debate going with those. :swordfigh

Has anyone with a forge tried to hold a piece of high carbon a bit below critical long enough for carbides to segregate out? I have heard that it can be done and that this is what http://www.angelsword.com/techno_wootz_steel.php is, I think. If the starting steel doesn't have enough carbon you end up with something that won't harden, but is very abrasion resistant, it will skate a file, but the edge with roll easily. I would like to try, but I probably can't keep the steel hot enough for long enough.

 

[jason01]

I thought he was being perfectly serious. I thought it was something to do with carbide formation when the steel has been taken past non-magnetic and then quenched. I know some american smiths align thier forges etc in such a way - unless of course they are all wind up merchants.

Yep, completely serious! Its a little custom Ive adopted that does no harm but I cant back it up with any consistent proof. I like to quench in water and anything that might help avoid warping cant hurt . I triple normalise, single quench, temper in the oven. I'm not keen on a triple quench, but each to their own

 

[G Obach]

hi

if you forge out a piece of 52100 into a blade.... often it'll have some kind of banding show up.... after heat treating it... just give it a dunk in dilute ferric chloride and alot of the times you get a neat pattern...

yep... that co. produces something that should more accurately be called
" techno banding".....

if you do the triple quench..... it works if you use the high alloyed steel like 52100.. ... i haven't heard of it benefiting the simple carbon steels...

"freezer cooling"..... some steels have a habit of retaining austenite... (such as the high alloys and stainless)..... and to fully convert it ... you must reach martensite finish.... which often is a temp that is bellow zero.......so, some undercooling is required with these steels... ... ( dry ice or liquid N )
-- austenite can sometimes be tripped off by the first oven temper.... or by sitting for a length of time...

isn't metalurgy fun...

take care
Greg

 

[C_Claycomb]

I have to admit to being a bit sad, I have been rather enjoying reading about metallurgy lately. I actually printed out the e-book below and have been reading it for the last few weeks, along with a MASSIVE thread on Bladeforums about the triple quench.

http://mse.iastate.edu/files/verhoeven/7-5.pdf

See page 16:
http://www.bladeforums.com/forums/showthread.php?t=268912

Reading this stuff has really started to make me question how I have been heat treating my O-1. I have started doing samples, trying different numbers of heats, quench temperatures, soaks. I have bought hardness testing files and hope to get some pictures of grain structure. The hardest, finest grain sample was held above critical in my one brick forge for 5 minutes, then after a couple of normalising cool offs soaked again for 4 minutes then quenched. I was astounded, after having read so many knife making books talk about quenching soon after critical is reached. The trick will be to do it consistently in blades!

I also found that, just as the books say, that the steel is far from full hard straight after an oil quench. Its still quite plastic.

Metallurgy rocks

 

[scruff]

not sad at all mr c

thanks for pointing those two links out. just skimming over them they already seem to be pretty interesting