BS 07/30165635 DC BS EN 4635. Aerospace series. Screws, 100 degrees countersunk head, six lobes recess, short thread, in heat resisting nickel base alloy NI-PH2601 (Inconel 718). Classification: 1 270 MPa (at ambient temperature) / 650 degreesC

standard by BSI Group, 05/02/2007