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Definition: Material specifications are binding technical stipulations regarding the chemical composition, mechanical properties, heat treatment and testing requirements of a material. They are based on standards or project-specific requirements. The aim is to define the material quality unambiguously.

Practical relevance: Specifications frequently refer to standards such as EN 10025, ASTM A516 or ISO material numbers. They define limit values for alloying elements, minimum strengths, impact energy, hardness ranges as well as the required test certificates (EN 10204). Unclear specifications increase the risk of material deviations and liability cases.

Decision-making perspectives:

• Technical decision-makers: Ensuring functionally and safety-appropriate material selection.
• Purchasing/project management: Contractually clear definition of scope of supply and quality verifications.
• Science: Assessment of material characteristic values in the context of new applications.
• Insurance/law: Basis for assessing contractual and quality deviations.

Typical testing or verification methods: Spectral analysis, mechanical materials testing, test certificates in accordance with EN 10204, comparison with standard tables.

FAQ:

• Why are precise material specifications important?
• They avoid scope for interpretation and ensure that materials meet the required technical properties.

Definition: Materials analysis is the systematic investigation of the chemical composition, microstructure and mechanical properties of a material. It serves to verify specification conformity as well as to determine the causes of failure. The analysis combines spectroscopic, microscopic and mechanical testing methods.

Practical relevance: Typical methods are spectral analysis (OES, XRF), metallography, scanning electron microscopy (SEM/EDX), hardness testing as well as tensile or impact testing. Alloying elements are assessed in accordance with the material standard (e.g. EN 10025, ASTM), grain size according to DIN EN ISO 643, phase fractions and characteristic values such as strength or toughness. The results are central to quality control, PMI and failure investigation.

Decision-making perspectives:

• Technical decision-makers: Verification of material conditions, heat treatment and microstructure quality.
• Purchasing/project management: Comparison with technical delivery conditions and test certificates (EN 10204).
• Science: Correlation of microstructure, composition and mechanical behaviour.
• Insurance/law: Court-proof evidence of material deviations or failure mechanisms.

Typical testing or verification methods: OES, XRF, SEM/EDX, metallography, hardness testing, tensile test, notched bar impact test.

FAQ:

• When is a materials analysis required?
• In the case of quality deviations, failures or to verify the material specification at incoming goods inspection.

Definition: Materials testing comprises all test methods for determining the mechanical, physical and chemical properties of a material. It serves to establish standardised characteristic values and to verify conformity with specifications. Tests can be carried out destructively or non-destructively.

Practical relevance: Typical mechanical tests are the tensile test (DIN EN ISO 6892-1), hardness testing (ISO 6506/6507/6508) and the notched-bar impact test (ISO 148-1). These are complemented by corrosion tests, microstructure analyses and spectral analyses. The results form the basis for material releases, quality assurance and safety assessments.

Decision-making perspectives:

• Technical decision-makers: Assessment of strength, toughness and suitability for defined operating conditions.
• Purchasing/project management: Requirement for standard-compliant test certificates (e.g. EN 10204 3.1) and acceptance criteria.
• Science: Analysis of relationships between microstructure and characteristic values.
• Insurance/law: Verification of specification-compliant properties in disputes or damage cases.

Typical testing or verification methods: Tensile test, hardness testing, notched-bar impact test, metallography, spectral analysis, NDT.

FAQ:

• What is the difference between destructive and non-destructive materials testing?
• Destructive tests determine characteristic values up to failure, whereas non-destructive methods test components without causing damage.

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.

Definition: Molten salts are melted inorganic salts used as heat-transfer, reaction or heat-treatment media at elevated temperatures. Typical systems are based on nitrates, chlorides or carbonates. They are characterised by high heat capacity and thermal stability.

Practical relevance: Applications are found in heat treatment, solar thermal energy or the chemical process industry. Molten salts can be highly corrosive, particularly towards unalloyed or low-alloy steels. Temperature range, oxygen content, impurities and material resistance are assessed. Suitable materials or coatings are decisive for plant integrity.

Decision-making perspectives:

• Technical decision-makers: Selection of corrosion-resistant materials and monitoring of the salt chemistry.
• Purchasing/project management: Specification of suitable material grades and testing requirements.
• Science: Investigation of high-temperature corrosion and diffusion processes.
• Insurance/law: Assessment of corrosion damage and compliance with technical codes and standards.

Typical testing or verification methods: High-temperature corrosion tests, metallography, weight-loss measurement, materials analysis.

FAQ:

• Why are molten salts corrosive?
• Molten salts can destabilise protective layers and promote electrochemical reactions at high temperatures.