A screw thread is cold rolled on a 1015 low-carbon steel bolt of 6.25 mm diameter.
Observation shows that the length of the contact zone between die and screw blank is L= 1.25 mm. The average strain hardening during rolling corresponds to a strain ofe= 0.4.
Calculate:
(a) the applicable flow stress, and
(b) the average interface pressure in the contact zone.
Determine:
(c) if there is any danger of internal fracture (make a sketch to illustrate the point).