[QuinnSjoblom]

Ive been making folding knives from 6al-4v titanium (the handles) and i want to learn everything i can about how to best handle the material. I havent had any major problems, but theres a few things i would like to address. First of all is the grain direction of titanium sheets. I cant find much info on what effect this has on the final parts and the machining other than just a general claim that it has better strength along grain direction. Is there anywhere i would find actual numbers on the difference in properties when comparing with grain and against grain? If its only a few percent difference, it would be much more convenient for me to not always orient parts lengthwise with grain. sometimes things would fit better the other way.
My next area of curiosity is dealing with warping of parts. my parts have pockets in one face only which causes uneven removal of stress which almost always leads to the part curling up toward the pocketed face. I know that i can rough, then refixture allowing it to bow before finishing, but im wondering if theres any other way to deal with this issue. Maybe grain direction has an affect on how sensitive it is to this bowing from material removal?
I have a lot of other questions about processing titanium but just dont know where to find the info. Is there maybe any good books on the subject?

[peteeng]

Hi Quinn - what temper 6-4 are you using? The material supplier will be able to supply a data sheet with the long and short properties of the material. It will depend on its temper and its work (rolling) history. Peter

[QuinnSjoblom]

Hi Quinn - what temper 6-4 are you using? The material supplier will be able to supply a data sheet with the long and short properties of the material. It will depend on its temper and its work (rolling) history. Peter

I'm not actually sure. I purchased the current sheet I have on eBay because it was a great deal. It is listed as vsmpo, ams 4911 and grain direction is labeled. Does ams 4911 tell the whole story, or can there be various tempers within that category? I'm a self taught machinest so I'm a bit lacking in technical knowledge about material specification.

I would be more worried about buying from a supplier with a legit paper trail on the material if I was providing parts made to spec to a customer, but this titanium is for handles of folding knives that I produce and sell.

Can some general assumptions be made about my material without having a data sheet with specifics? I guess what I'm hoping to gain is just a better general knowledge of this material and how to best handle it. Like for example can it be assumed my material is at least 80% as rigid across the grain as it is with the grain? And will warping from material removal be more significant in one of those directions specifically? Or are these just not answerable questions without a data sheet?

[peteeng]

Hi Quinn - a quick search shows ams4911 is annealed, which means it won't have a grain. The stiffness of the material will not be different in the short or long direction. Even in the normalised or hard condition the stiffness is not different. What can be different is that due to rolling (work hardening) the internal strain is different in the two directions. This strain relieves when machined so it cups. Peter

What is metal stress relief? | ShapeCUT

[QuinnSjoblom]

Interesting, sounds like just typical internet misinformation then. When researching I found a couple instances of guys mentioning orienting parts in 6al4v along grain for best rigidity. Good to know I can place parts either way.

Now when a supplier labels the "grain direction" on annealed plate, are they just referring to the direction it was rolled?

On the subject of the direction it was rolled, it is more likely to bow in one direction vs the other when material is removed from one face? I understand there are internal stresses and why it bows when relieving those stresses from one face, just curious if it's more significant aling one direction

[peteeng]

Hi Quinn - Lots of misinfo out there. Yes the roll or long direction is noted on the sheet. Also if its "hard" the grain will show up in processes like anodising or etching so if you want to grain match its good to know the grain direction. Peter