This specification covers the grain flow pattern requirements in headed bolts, screws, and studs. The heading practice in the manufacture of the bolt, screw, or stud sets the grain flow pattern, but it is also greatly influenced by the fastener and tooling design as well as cold-forging setup. The use of tooling design simulation software is recommended and a commonly used practice that provides reliable forging predictions for superior grain flow quality.
SAE USCAR8-4-2019 history
2019SAE USCAR8-4-2019 GRAIN FLOW PATTERN FOR BOLTS, SCREWS, AND STUDS