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The Folding Knife (& Switchblade) Forum The materials, techniques and the designing of folding knives. |
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#16
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Quote:
"strength of alpha-beta alloys can be increased about 35% by heat treating, compared with properties of annealed material" Introduction To Physical Metallurgy(second edition) by Avner, Sidney (it also shows a picture of martensite formation after heating to 1950 and water quenching) "an alloy such as 6al4v....has a 2 phase structure, about 1/2 beta and 1/2 alpha phase. when this alloy is heat treated to a temperature of about 1725 it completely transforms to beta structure. when it is water quenched to room temperature part of the beta phase is metastable; it wants to transform to alpha but this was prevented by the water quench. this is called solution treating, and the alloy has high strength in this condition, but hardness and strength can be further increased by aging for 4h at about 1000degrees. in the aging operation, discrete zones of alpha phase precipitate from the metastable beta phase. thus alpha-beta alloys are considered to be precipitation hardening alloys. there are various alpha-beta alloys with different precipitation hardening mechanisms but the 6al4v alloy is the most important of the group." Engineering Materials(4th edition) by Kenneth G Budinski these were from a few old college books i have laying around....i did a net search(yahoo) for "heat treating titanium" and found multiple sites with info...im not going to quote them unless requested. "By far, the most common alloy in use today is Ti-6Al-4V, which contains 6% aluminum, 4% vanadium, and approximately 90% titanium. In the annealed condition, ultimate tensile strength is a minimum of 130,000 psi with a hardness in the Rockwell C (RC) 32 range. Heat treatment can increase the strength to 160,000 psi and a peak hardness of Rc 38. " this is taken from Mission Knives website http://www.missionknives.com/Indexframes.html -Jason Aube Last edited by AUBE; 04-26-2004 at 04:37 PM. |
#17
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Aube,
That's some very interesting information. I've printed your tech quotes and, first opportunity, plan to put some scrap 6al4v in my HT oven to seen what happens. One thing I have noticed when forming pocket clips and such out of ti with a torch, other than the spectacular colors, is that the metal appears to become "springier" at the bends. (It also polishes brighter but with slightly more effort ) So, heat to 1725, quench in water. Soak at 1000 for four hours, gains about 6 Rockwell points. Worth checking out.... -Frank J Warner __________________ --Frank J Warner Happiness is tight gibs and a flat platen. http://www.franksknives.com/ |
#18
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i used to make body jewelry out of CP Ti and 6al4v...at the time i wasnt aware some titanium alloys were heat treatable. when i was doing torch coloring of some rings and dipping them in water to cool them..i also noticed extra spring to them. when i made the few linerlocks that ive made i did the torch method..seemed springier. thats the extent of my testing lol let me know how it turns out Frank -Jason Aube |
#19
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Jason, thanks for posting some interesting information! I'm glad to see something I can take to the heat treater. Ive never seen any info before about martensite formation in titanium.
Frank, I hope you will do a test, I lack an oven so I cant. Maybe one of the titanium manufacturers will come up with some tables... or you can from your testing!! __________________ www.wilkins-knives.com www.wilkins.de |
#20
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your welcome.
i just wish i had more detailed info on the subject, as youve noticed its a bit hard to come by. my books dont go into detail because they cover so many other topics. they dont even say what type of "quench" to do after the 4h 1000 cycle. im assuming slow air cool but what happens if its rapidly air cooled, or very slowly cooled? what happens if u raise or lower the soak time/temp? so many variables and so little available info ive been meaning to do some research on titanium, beta alloys in specific. ive read they can be hardened to mid-high 40's on the rc and coupled with abrasion resistance can make a decent blade. hopefully the local library will have some books on the subject because these types of books are expensive! i think ill start saving all the data i come across and maybe if i get enough bits and pieces it might start to add up. if anyone has some good links or sources on this type of thing please let me know -Jason Aube |
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