Strain Gages on Titanium

Titanium is a very useful structural material.  Having properties of high strength, light weight, and high temperature capability, it is often the subject of strain measurements for design verification.  Titanium also has some properties of which a stress analyst must be aware of in order to obtain successful strain gage installations and subsequent measurements.  Detailed instructions for the correct surface preparation of titanium and other materials can be found in Micro-Measurements Instruction Bulletin B-129 “Surface Preparation for Strain Gage Bonding”.  The chart of materials lists steps for titanium on page 7. Here are the things of which you need to be aware.

1.  CSM- degreaser should not be used on titanium, nor should any other solvent that contains halogens, since micro-cracking could occur later if the testing is to be done at temperatures above 700 deg F.  Micro-Measurements GC-6 Alcohol is a good choice for degreasing titanium.
2. Heat cycling is necessary in order to remove oils.  This is very important in being able to get strain gages to bond to titanium with any adhesive.  Micro-Measurements recommends heat cycling two or three times to +350 deg F, letting it cool to room temperature and degreasing between each cycle.  This will drive oils from the surface which will be removed during degreasing.
3. Following degreasing, the surface should be wet abraded with M-Prep Conditioner A and 320-grit silicon carbide, and followed with a M-Prep Neutralizer 5A scrub/dry step.
4. Titanium oxidizes very quickly.  Strain gages should be bonded within 10 minutes after surface preparation.

For more information on selecting strain gages and bonding materials, contact a Micro-Measurements Applications Engineer, Technical Sales Manager, or independent Sales Representative at mm@vpgsensors.com.