The details are based are based on VDI 2230, edition 2015: prestressing forces and tightening torques for headless screws of strength classes 8.8 to 12.9 for a 90 % utilisation of the yield point Rp 0,2.
The table does not include any factors of safety and assumes the user is familiar with the design criteria.
See Page F.045 for an explanation of the friction coefficient μ.