- Cutting and Rough Grinding
- Cutting and rough grinding is performed to obtain a representative
metallographic specimen from the component.
- The orientations are longitudinal and transverse.
- Mounting and Fine Grinding
- Mounting is performed in a mounting press, which encapsulates the specimen
with a thermosetting resin under pressure and at an elevated temperature.
- Four-stage manual fine grinding: a successive series of water-lubricated
papers (beginning with 240 grit and finishing with 600 grit) is used.
- The mounted specimen is abraded backward and forward without rotation
until all grinding marks from the previous coarser abrasive paper have
- The direction of grinding is changed 90 degree with each change of
abrasive paper, so that removal of the previous grinding marks is easily
- Rough and Final Polishing
- Rough polishing is performed on a series of rotating wheels covered
with a low-nap cloth. Succesively finer grades of polishing powders are
applied to each wheel, starting at 45 micron size and then decreasing to
30 micron, 6 micron, and 1 micron. A small amount of lubricant is applied
to the cloth to prevent overheating of the mount.
- In final polishing, a 0.3 micron to 0.05 micron alumina slurry in water
is applied to a medium-nap cloth.
- The vibratory polishing machine named SYNTRAN is used for final polishing
in our case.