i'm looking for a 400mm piece of steel rod/bar 10mm diameter. needs to be 12.9 tensile strength. (or 4 x 100mm pieces)

What are you doing with it?

I assume you are making some suspension pivot bars? You could just use EN16T, or if you want silly strength EN24T, but be warned its a bugger to machine.

Ive heard of people using EN8. Im not au fait with EN8, but my guess would be that it machines easier than 16/24...

Ed.

could't you just get cap head allen bolts and cut the heads off? http://www.fastfixdirect.co.uk/code/FilterResults.asp?fType=Fasteners&MainCategoryID=19&ProductCategoryID=418
not that expensive either