Metal finishing Q&As since 1989


-----

Possibility shot peening, for work hardening of titanium fasteners

We would like to take up a project on development of lightweight fasteners (Titanium alloy) for aerospace applications. One of our objective is to improve the work hardening of the shank of the fastener for better fatigue resistance. Conventionally this is being done by cold forming operations like Rotary Swaging.

Now, as a preliminary study of the project, we would like to find out whether the same can be improved by shotpeening operation? As, shotpeening improves fatigue resistance as used in Spring manufacturing process, can that be employed for fasteners too?

Thanking you in anticipation

M.S.V.S.RAMA KRISHNA
- KAKINADA, EAST GODAVARI DIST, ANDHRA PRADESH, INDIA
2002

---

Shotpeening is used for a lot of things besides springs, including highly stressed lightweight parts like landing gear. The basic reason it improves fatigue resistance is because it puts the outermost surfaces under compressive stress; if you can keep the surface from going highly tensile you can fight crack propagation. I don't know if titanium in general, or the temper you are using in particular, can be greatly helped by peening, or if there is something peculiar about the metallurgy that precludes it, but in principle peening should help fatigue resistance.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2002