Macro Etch Inspection (MEI)
Macro Etch Inspection (MEI) involves the selective chemical cleaning of the inter-granular area with the use of chemical substances, as well as enhancing visual contrast between the inter-granular areas with the grains of the metallic material.
Macro Etch Inspection is used for the detection of surface breaking discontinuities, for the qualitative differentiation of grain sizes as well as grain orientation. Certain phases of metallurgy can also be identified with the use of this NDT method.
The equipment that is used for this Non Destructive Testing method varies from plain magnifying glasses to portable or stable microscopes.
Course Content
- Introduction, use and applications
- Safety measures
- Surface preparation (including grinding and polishing)
- The process of chemical etching
- Preservation of tested items
- Usual etchants and choice of etchant
- Replication techniques, including acetate replica
- Discontinuities due to grinding abuse
- MEI to reveal grinding abuse
- Characteristics of grinding abuse flaws
- Failure of metals and steel
- Fracture surfaces and fractographic characteristics
- Applicable standards
- Extensive practical element
Responsibilities of a Macro-Etch Inspector Level 2 NDT professional:
- Select the Macro-Etch technique for the test method to be used
- Define the limitations of application of the testing method
- Translate NDT codes, standards, specifications and procedures into NDT instructions adapted to the actual working conditions
- Set up and verify equipment settings
- Perform and supervise tests
- Interpret and evaluate results according to applicable standards, codes, specifications or procedures
- Prepare Macro-Etch written instructions
- Carry out and supervise all tasks at or below level 2
- Provide guidance for personnel at or below level 2
- Report the results of Macro-Etch test
