Q: We have gear mounted alloy steel screws that rotate a loaded arm. As the gear rotates over its lifetime, these screws ultimately stretch and wear resulting in the bolts loosening, shearing, and breaking. Is there a screw material capable of being made that would help solve any of these issues: less likely to loosen, as well as more resistance to wear, stretching and shearing?
A: For your application if the material creeping is the issue you might want to try an age hardened stainless steel that is more resilient to these forces. A material to consider would be 17-4 PH particularly in the H900 condition. (https://www.extreme-bolt.com/17-4-ph-fasteners-flanges.html#ASTMA564GR630). 17-4 bolts will provide a low elongation and have a higher yield point, which may improve your situation.