The material for bolts will be allow steel- hardened and tempered condition,

A few sites that may be useful to you are

http://euler9.tripod.com/bolt-database/22.html

http://mdmetric.com/fastindx/t17u.pdf

Also the home page of this site will give you a lot of useful information on fasteners

http://mdmetric.com/fastindx/inxtst.htm

http://www.co-design.co.uk/dpg/bol/bol6.html

Hope these will be enough

The last link permits Carbon steel also, however our experience (as users) has shown that the fasteners when they are made of C-Steel and heat treated to achive properties, have not fared well and failures in operationwere very high.

We specify EN 10083 - 42CrMo4,

The exact material may be selected based on the above guidelines.

12.9 bolts are made to ASTM A574M

we use sae4140 or en-19/en-24 as per the application /cost - as per the requirements of the consumer

SAE or AISI 4140, or ASTM A322 grade 4140 is equivalent to the German 42CrMo4.

Special bolts or studs (no stock from suppliers and urgent)were made to me so:

12.9:sae4140 heat treatment;10.9:sae4140 not heat treatment;8.8:sae 1045 if it is smaller diameter than 1''.When you are in doubt use 4140 with heat treat.or when was needed fast and not time for h.t. i used sae4340,even better than 4140:150 kg/mm2 versus 120 kg/mm2 (both with h.t.).Of course this just in case you are from a common workshop trying supply fast your customer...not for a regular bolts manufacturer who,i think, should try its own sources for standards.-