Background

Aside from mechanical damage, parts distort from inherited or induced stresses during machining or thermal processing. We have successfully straightened several hundred titanium alloy airframe parts in the past 12 years. I find that it is usually cost effective to straighten titanium alloy airframe parts, but from my research, straightening of titanium alloy parts is not a well-documented process. Normally, titanium alloy parts must be straightened at high temperatures in order to maintain needed fatigue properties and to facilitate part movement (creep). Titanium parts are very expensive because of high material and machining costs; obtaining replacement material (to cover scrapped parts) can be difficult. The cost of straightening a part is usually less than the replacement cost, and schedule requirements may force a decision to straighten because we do not have time to build a new part.

We keep learning more about the causes of titanium alloy warpage. This knowledge helps us to develop preventative measures that we can take to minimize warpage. We are also doing continuous research to improve the straightening processes.

Problem

Titanium alloy parts warp during machining or thermal processing. Parts also get bent from mechanical damage. The extended problem is to make decisions on the following issues:

1. Can the part be used as is?

2. Do we scrap the part?

3. If the decision is to straighten, which method of straightening...