Metallurgy Testing
Metallurgy testing is a skill, an art, a science to reveal prior processing of materials. Samples are polished to a mirror finish, etched in acid, to reveal the grain structure, impurities, and other features. The size of the grains govern the hardness and tensile strength of the material.
- Processing – casting, hot work, cold work, heat treatment, quenching
- Structure – grain size, crystal structure
- Material Selection – alloy
- Performance – strength, corrosion, wear, fatigue, toughness, fracture toughness
Tools of the trade and their benefit:
Literature review
- obtain relevant information from failure site
- conduct literature review to verify material behavior
- locate specifications for performance and processing and compare actual data to standards
- ASTM, ASM handbooks, material supplier certifications
Macroscopy and SEM
- ductile-brittle failure mode
- crack initiation site
- cause of crack
- types of corrosion
- fatigue performance
Microscopy
- phases present are a function of temperature history
- types of corrosion
- internal defects
Mechanical testing
- failure load
- impact properties
- hardness
- wear resistance
- bend deflection
- yield strength, ultimate tensile strength
- fatigue
Analytical chemistry
- Determine material composition and then corresponding alloy
- Performance will be determined by prior processing