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Definition: Component metallography is the metallographic examination of the microstructure directly on the component or on representatively extracted samples. It serves to assess heat-treatment conditions, weld seam qualities and damage-relevant microstructural changes. It is based on preparative sectioning techniques as well as light or electron microscopy analyses.

Practical relevance: Grain size (DIN EN ISO 643), phase distribution, precipitates, crack formation or decarburisation depths are evaluated. The method is central to failure analysis, in cases of suspected HTHA (High Temperature Hydrogen Attack) or for verifying material specifications. Replica techniques enable in-situ examinations without full disassembly.

Decision-making perspectives:

• Technical decision-makers: assessment of microstructural inhomogeneities, weld seam zones and remaining service life.
• Purchasing/project management: verification of specification-compliant heat treatment and manufacturing quality.
• Science: microstructure analysis, correlation of microstructure and mechanical properties.
• Insurance/law: documentation of the material condition to secure evidence in the event of damage.

Typical testing or verification methods: sample preparation, light microscopy, scanning electron microscopy (SEM), hardness testing, microstructure etching.

FAQ:

• Is component metallography possible non-destructively?
• Replica methods are minimally invasive; classic sectioning examinations require material extraction.

Definition: The compression test is a mechanical testing method for determining the behaviour of a material under axial compressive loading. A cylindrical or prismatic specimen is loaded between two compression platens up to a defined load or until failure. The method is standardised, among others, in DIN EN ISO 6892-1 (for metals, complementing the tensile test).

Practical relevance: The properties determined are compressive strength, modulus of elasticity and plastic compression behaviour. The compression test is particularly relevant for brittle materials such as cast iron, ceramics or concrete, where the compressive strength is considerably higher than the tensile strength. Influencing factors are specimen geometry, friction at the compression platens and testing speed.

Decision-making perspectives:

• Technical decision-makers: Design of compression-loaded components and assessment of failure mechanisms.
• Purchasing/project management: Specification of required minimum compressive strengths in material specifications.
• Science: Analysis of non-linear deformation mechanisms and material models.
• Insurance/law: Documented verification of mechanical properties in cases of structural failure.

Typical testing or verification methods: Universal testing machine with compression platens, strain measurement, evaluation of stress-strain curves.

FAQ:

• When is a compression test more appropriate than a tensile test?
• For brittle materials or components that are predominantly subjected to compression, the compression test provides more realistic characteristic values.