Wiki

Definition: Measurement methods are systematic procedures for the quantitative determination of physical, geometric or chemical quantities. They serve to objectively record actual values and to compare them with specified target requirements. They are based on defined measurement principles, calibration and known measurement uncertainty.

Practical relevance: In materials testing and quality assurance, tactile, optical, electrical and non-destructive measurement methods (NDT) are used. Selection criteria are measuring range, accuracy, resolution, reproducibility and standard conformity (e.g. ISO 10360 for CMMs, ISO 6507 for hardness testing). A documented measurement uncertainty analysis is required in particular in regulated industries.

Decision-making perspectives:

• Technical decision-makers: Selection of suitable measurement principles for function- and safety-critical characteristics.
• Purchasing/project management: Definition of testable specifications and acceptance criteria.
• Science: Validation of measurement methods, uncertainty budget and comparative studies.
• Insurance/law: Traceability and verifiability of measurement results as evidence.

Typical testing or verification methods: Coordinate measuring technology, roughness measurement, hardness testing, spectroscopic analysis, ultrasonic testing.

FAQ:

• Why is measurement uncertainty decisive?
• It determines whether a measured value lies within or outside a tolerance with sufficient certainty.

Metallography

Definition: Metallography is the preparative and microscopic examination of the microstructure of metallic materials. The aim is to analyse grain size, phase distribution, precipitates and defects. It forms the basis for assessing material conditions and failure mechanisms.

Practical relevance: The procedure comprises sampling, mounting, grinding, polishing and etching, as well as examination using a light microscope or scanning electron microscope (SEM). Items assessed include grain size according to DIN EN ISO 643, weld seam microstructure, decarburisation and crack initiation. Metallography is central to failure analysis, heat treatment testing and quality assurance.

Decision-making perspectives:

• Technical decision-makers: Assessment of microstructure quality, heat treatment and manufacturing parameters.
• Purchasing/project management: Verification of specification-compliant material conditions.
• Science: Microstructure analysis and correlation with mechanical properties.
• Insurance/law: Microscopic verification of material-related failure causes.

Typical testing or verification methods: Specimen preparation, microstructure etching, light microscopy, SEM, EBSD, hardness testing.

FAQ:

• Why is etching necessary in metallography?
• Etching makes microstructural constituents and grain boundaries visible that are not discernible in the polished condition.