SAE AS 4877F:2017 – Bolts and Screws,Nickel Alloy UNS N07718, Classification: 185 ksi/1200 °F Procurement Specification.
3.3 Fabrication
3.3.1 Blanks
Heads shall be formed by hot forging or cold forging; temperature for hot forging blanks shall be within the range of 1650 to 2000 °F. Machined heads are not permitted, except lightening holes may be produced by any suitable method. Wrenching recesses may be forged or machined. Flash or ch clearance in machined recesses shall not cause recess dimensions to exceed the specified limits.
3.3.2 Heat Treatment
Headed blanks, before finishing the shank and the bearing surface of the head, cold rolling the head-to-shank fillet radius, and rolling the threads, shall be solution and preclptatlon heat treated as follows: Heating Equipment
Furnaces may be any type ensuring uniform temperature throughout the parts being heated and shall be equipped with. and operated by, automatic temperature controllers and data recorders conforming to AMS2750. The heating medium or atmosphere shall cause no surface hardening by carburizing or nitriding. The heal treatment atmosphere or medium shall not cause any surface contamination except as permitted by 3.3.3. On unpiated bolts, discoloration from heat treatment is acceptable but no scale is permissible. Solution Heat Treatment
Headed blanks shall be solution heat treated by heating to a temperature within the range 1725 to 1850 °F, holding at the selected temperature within ±25 °F tori hour ±0.1 hour, and quenching in oil, waler, or an inert gas. Precipitation Heat Treatment
After solution heat treatment as in 3.3,2.2, headed blanks shall be precipitation heat treated by heating to 1325 °F ± 15 °F
In a controlled atmosphere, holding at heat for 8 hours ± 0.25 hour. furnace cooling at 100°F ± 15°F per hour to 1150°F ±
15 °F. holding at 1150°F ± 15°F for 8 hours ± 0.25 hour and cooling at a rate equivalent to air cool. Instead of the 100 °F
per hour cooling rate to 1150 °F ± 15 °F, parts may be furnace cooled at any rate provided the time at 1150 °F t 15 °F is
adjusted to give a total precipitation heat treatment time of approximately 18 hours.
3.3.3 Oxide Removal
Surface oxide and oxide penetration resulting from prior heat treatment shall be removed from the full body diameter and bearing surface of the head of the solution and precipitation heat treated blanks prior to cold rolling the fillet radius and rolling the threads. The oxide removal process shall produce no inlergranular attack or corrosion of the blanks. The metal removed from the bearing surface of the head and the full body diameter of the shank shall be as little as practicable to obtain a dean, smooth surface,
3.3.4 Cold Rolling of Fillet Radius
After removal of oxide as in 3.33, the head-to-shank fillet radius of parts having the radius complete throughout the circumference of the part shall be cold rolled. Cold rolling shall be sufficient to remove all visual evidence of grinding or tool marks. Distortion due to cold rolling shall conform to Figure 1, unless otherwise specified on the part drawing. It shall not raise metal more than 0.002 inch above the contour at “A” or depress metal more than 0.002 inch below the contour at ‘B” as shown in Figure 1; distorted areas shall not extend beyond ‘C” as shown in Figure 1. In configurations having an undercut connected with the fillet radius, the cold rolling will be required only for 90° of fillet arc, starting at the point of tangency of the fillet radius and the bearing surface of the head. For shouldered bolts having an unthreaded shank diameter larger than the thread major diameter and having an undercut connected with a fillet between the threaded shank and the shoulder of the unthreaded shank, the cold rolling will be required only for 90° of fillet arc, starling at the point of tangency of the fillet radius and the shouldered surface of the unthreaded shank. The shank diameter on full shank close tolerance bolts shall not exceed the nominal thread diameter after cold rolling the head-to-shank fillet radius.