Strongest filament for FFF (FDM) 3D Printer?

What would be the absolute strongest filament / material that I could print with on an FDM 3D printer? I know ABS is slightly stronger than PLA. Is there any sort of other materials that are stronger, or brands that are strongest?

I'm pretty sure with most 3D printers, the strongest material you can use is ABS. Although I do see some new materials coming out, such as the bronzefill from colorfabb, which has particles of bronze in it. I would assume this stuff could be stronger, but have not tried it myself.

When our new heads come out, we will be able to print in PEEK.

There is also some ABS filament with carbon fibers in it, but I haven't tested it or seen reports of its strength yet.

What do you mean by strongest? That it won't deform or that it won't break? I think Nylon is the strongest commonly available printing material, I've seen a video of a guy running his car over a ball printed in Nylon and while it did deform under the weight, it didn't break.

It appears to me that ABS is actually the worst of the group in every possible aspect. It fumes, it needs heated bed, it shrinks, it has layer bonding issues and it is not though or strong at all.

http://3dprint.com/14533/3d-print-material-test/

I think that PLA, especially the most recent developments which brings its toughness up to 8x the original formula, is the best material and on its side stands the nylon. Nylon outperforms PLA on many aspects though so it is purpose-based question. If i'd have to choose one material I would pick for nylon, it is as good as PLA, but it stands weather, it is not as brittle and even to that it is more available.

I view 3D materials and printing techniques exclusively by their mechanical properties, not for modeling bookshelf decorations so some materials may perform better for that purpose.

I'm gonna guess this would rank up at the top...

http://www.proto-pasta.com/shop/pcabs

Also my PLA print's seem weaker than my ABS print's. Just what I've noticed.

my pla are defintiely tougher than my abs.

The urethane filaments are really strong and the polyflex flexible pla is even stronger.

The currently strongest material you can print on an fdm is with the markforge printer that uses carbon fibre, kevlar and fibreglass reinforcement into standard pla/abs.

The metal powder filaments are actually the weakest materials you can curently print with. The metal particles are not melted and do not bond with the plastic. So what you end up with is a weak plastic foam with metal filling the holes, but adding absolutely no structural strength at all.

Next up would be the carbon fibre and graphene infused filaments. But they don't produce a continuous fibre reinforcement like the markforge head does.

I'm with 3dwinter on abs. It's just not worth the hassle.
pet is as strong and with fewer of the halles.
And the new pla+ filaments are stronger than abs.

Nylon is very very strong - but an absolute bastard to print with.

It's all relative. I have to say the reprapper tech ltd pla I use is definitely tougher, less brittle and at least as strong as the abs I've got.
But then you can get abs+ as well.

It's an exponentially expanding market and the materials chemists are having a field day.

i agree with caa. there are just so many filaments out there now all with different properties. strength is such a broad term. strength in what way is really the question. nylon is extremely strong as for durability and impact resistance but its very weak in the fact that its a soft plastic and has no rigidity. pla is strong since its the most rigid of the bunch but it has no impact or heat resistance resistance. some can get softer and lose strength just from holding it in your hand. i personally find pla worthless for what i print mostly. like everyone has said abs has its own set of problems. prints great, layer adhesion can be extremely good to so so depending on the brand. its upper middle road as far as being rigid and impact resistance is great so it wont shatter. petg is way more rigid than nylon but a touch less than abs but even more impact resistant and layer bonding is crazy high. also the temp range is close to abs. colorfabb now has carbon fiber filled petg which just adds to the strength. overall its the most balanced of the filaments. generally way stronger than abs. no warp but more difficult to fine tune your settings and it doesnt bridge well. all in all there isnt a single material that fits the bill for every print. you have to use the material that is needed for the particular job.

My general rule of thumb (and there certainly are exceptions) is:

Inside item, mainly to be looked at and admired = PLA
Just about anything else = PETG
Eventually use it because I got it as a present = ABS :p

I still say today's pla is the best all rounder.

But that wasn't the question :-)