Identifying the internal structure of materials

Material and component characterization

To reach solutions for improving the reliability and useful life of materials and components, it is necessary to gain knowledge of the internal structure of those materials. Scientists at the Fraunhofer IWM investigate the reactions of materials and components to mechanical, thermal, chemo-mechanical and tribological loading and clarify their deformation and failure mechanisms. The necessary material parameters are obtained and evaluated in correlation to the microstructure and to structure-altering processes on all size scales. On this basis the Fraunhofer IWM offers materials development as well as process and technique development services.

The institute’s core competence of material and component characterization is derived from its capacity to develop and apply complex testing and analysis methods that go beyond standard procedures and which are thus able to meet the demands of a wide spectrum of simulation approaches tailored to the type and quality of the test data. The basis of this is on the one hand the availability of mechanical testing techniques for a very wide spectrum of temperature, environment and force ranges and load speeds, and on the other hand, expertise in both the selection of characterization methods appropriate to the material and application as well as in the evaluation of damage development. Component testing takes into account locally varying material properties. Additionally, fracture mechanics evaluations and damage analyses are performed.

Salient features of the scope of services include the capturing and evaluation of multiaxial stress conditions, locally obtaining parameters through micro-testing techniques and structure analysis, and expertise in the field of crack propagation, which may for example be used in the development of innovative separation processes. The portfolio is complemented by a range of high-resolution residual stress analysis techniques plus thermo-physical and thermo-mechanical characterization

 

How to work with the Fraunhofer IWM

Possibilities for measurement and analysis


Experts at the Fraunhofer IWM work with the most up-to-date equipment available and develop special testing systems and experimental setups for individual customer queries.
The scientists working at the institute can obtain a large number of material and component properties using a variety of measurement and analysis methods.


On this page:

Static and cyclic material and component characterization

Thermo-mechanical material and component characterization

Micromechanical material and component characterization

Thermo-physical material properties

Chemo-mechanical material and component characterization – high vacuum

Metallography (clarification of microstructure)

Radiographic residual stress measurements

Characterization of granulates and their behavior during processing

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Static and cyclic material and component characterization

 

Static strength, multiaxiality parameters, vibration resistance, fracture toughness, crack growth, torsional stiffness, tested using servo hydraulic, electrodynamic and electromechanical testing machines:

Tension, compression, shear

Test forces from 10 mN to 8 MN

Test chambers from 100 to 2500 K

2D and 3D strain measurement using grayscale correlation (ARAMIS)

Experiments performed on the basis of force or strain

Single-step tests; variable-amplitude tests

Various methods for measuring crack length, including ASTM 1820, ASTM 1921, ASTM 647


Fretting fatigue using a module for application of simultaneous combined longitudinal and transverse forces

Component strength evaluation in a stretching field with servo hydraulic (63 kN and 25 kN) cylinders and torsion cylinders up to 4 kNm

Module of elasticity, storage module and loss module obtained via dynamic mechanical analysis (18 mN to 500 N)


Natural frequencies, modal analysis, vibration testing and shock testing with climate-controlled shaker unit:

Sine force approx. 10 kN, random force approx. 10 kN, frequency up to 4000 Hz

Max. oscillation speed (sinusoidal) 1.8 m/s (dependent on test mass), oscillation displacement approx. 51 mm

Max. acceleration for sine/random 100 g/40 g (dependent on test mass)


Strain rate dependence measurement on high-speed tensile test machine (100 kN up to 20 m/s, 500 kN up to 10 m/s); drop rate testers and notch impact test rigs

Evaluation of creep behavior on temperate, climate-controlled test rigs

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Thermo-mechanical material and component characterization


Determination of fatigue life, yield point, tensile strength, elasticity modulus and crack growth using mechanical and/or servo hydraulic testing machines:

from -180°C to >1000°C

Isothermal or anisothermal (heating and cooling rates up to approx. 10°C/s)

Heating, inductive or in furnace

Controlled by strain or by tension

Typically cylindrical probes with diameter 5-10 mm

Hot tension tests to determine yield point, e.g. at 0.2% plastic strain

Modulus of elasticity obtained using resonance method by matching with stress-strain curve in linear range

Fatigue crack growth with typically a corner crack probe, diameter 8x8 mm in measurement range

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Micromechanical material and component characterization


Determination of modulus of elasticity, vibration resistance and sample natural frequency using microtension instruments:

Room temperature to 200 °C

Microsamples made in-house using customer’s material; sample thicknesses 10 to 400 µm, base material can be thicker

Test frequency 1200 Hz


Characterization using a resonant microfatigue testing unit:

Test frequency 1200 Hz through defined sample natural frequency/geometry, which is adjustable

Measurement of sample natural frequency, which changes as fatiguing progresses; detection of first damage well before initiation of cracks

 

Measurement of position, displacement and stretching using cameras, microscopes and scanning electron microscopes:

Optical strain measurement with digital image correlation for samples with characteristic surface (with features in the form of grayscale transitions)

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Thermo-physical material properties


Determination of specific heat capacity and quantitative determination of exothermic and endothermic reactions using dynamic differential scanning calorimeter, DSC:

Room temperature to 1600 °C with heating rates between 0.01 and 50 K/min

Determination of transformation temperatures

Quantitative determination of exothermic and endothermic reactions

Tests performed in various gas atmospheres and in vacuum

Typical sample size for solid bodies: 5 x 1.2 mm


Measurement of thermal expansion in length and coefficient of linear expansion, phase transformations and transformation temperatures, also of temperature-dependent density changes, using thermo-mechanical analyzer:

Room temperature to 1600 °C with heating rates between 0.1 and 20 K/min

Tests performed in various gas atmospheres and in vacuum

Typical sample size: Diameter 3-6 mm, length 10-25 mm; similar dimensions for plates


Analysis of thermal conductivity with laser-flash apparatus LFA:

Range of 0.01-1000 mm2/s and from room temperature to 2000 °C with heating rates between 0.1 and 50 K/min

Tests performed in various gas atmospheres and in vacuum

Sample dimensions for round samples 6, 10 and 12.7 mm diameter; for rectangular samples, max. 10 x 10 mm

Sample thickness to vary with the expected thermal conductivity


Determination of thermo-mechanical properties of metals using a Gleeble 3150 testing unit in gas atmospheres and in high vacuum:

Heating rate up to 8000 K/s and max. cooling approx. 2500 K/s

Application of stresses under regulation of force, strain and path

Tests performed in various gas atmospheres and in high vacuum

Load range 44 kN tensile/compression

Temperature range from room temperature to melting point

Tensile and compression tests with simultaneous thermal stress

Weld simulation and creation of various material conditions


Capturing of component geometries using a 3D laser scanner for optical scanning and sampling of components:

Focal distance 130 mm

Precision: approx. 25 µm

Evaluation software enables direct comparison between scan and CAD part and much more

Scan can be exported in all common CAD formats

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Chemo-mechanical material and component characterization – high vacuum


Determination of hydrogen and oxygen content using a suitable analyzer:

Hot extraction of carrier gases in inorganic materials

Sensitivity: 0.1-1000 ppm


Measurement of hydrogen content, determination of binding energies of hydrogen events; distinction of hydrogen trapped with different strengths using hot extraction analyzer for diffusible hydrogen and with thermal desorption spectroscopy:

Infrared oven up to 900°C; wire-wound tube oven up to 1100°C

Measurement range: 0.05-1000 ppm, resolution: 0.01 ppm


Determination of diffusion coefficients and kinetic constants of hydrogen events (trap and release relate) using permeation test rig:

Testing to DIN EN ISO 17081

Temperature control of samples


Analysis of mechanical properties during hydrogen embrittlement and of the mechanical behavior of coated samples using tensile, notch tensile, fatigue and crack propagation tests on servo-mechanical testing machines:

Stress corrosion cracking tests: CERT (or SSRT) tests: Tensile tests with slow strain rate, e.g. after ASTM G 129

Fluid media, molten salts up to 600°C, oxidizing atmosphere up to 900°C

Exposure tests in fluid/gaseous media (molten salts up to 1100°C)

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Metallography (clarification of microstructure)


Analysis of chemical composition using GDOES depth profile spectrometer:

Chemical composition of metals

Depth profiles possible up to approx. 100 µm

Calibrated for Fe and Ni-based materials


Measurement of nanoindentation hardness using a nano indenter:

Hardness measurement to DIN EN ISO14577

Creep loads adjustable up to 60 s

Force range 0.4 - 1000 mN

Measurable hardness range 0.001-120,000 N/mm²

Vickers or ball indentation

Automatically traveling measurement table for recording hardness mappings


Hardness measurement:

Hardening methods as per Vickers, Brinell, Knoop, Rockwell, Shore A

Manual or automatic (for hardness mappings or hardness curves)

All common load ranges, including as per DIN6507, 4545, 6506 or as per ASTM E384, E92, E384, E10


Analysis of local chemical composition using EDX, EDAX:

Measurement of local chemical composition

Elements with atomic number 6 or more (carbon) can be measured

Carbon is not quantifiable

Resolution dependent on sample material (approx. 1 µm)

Measurement of chemical composition at defined points, along lines or using element mappings

Particle and pore analyses (volume fraction, size distributions, form factors) using optical microscopes and an image processing system


Determination of crystal and grain orientation, texture, grain deformation; imaging of orientation maps by electron backscatter diffraction (EBSD):

Can be coupled to EDX

Angular precision approx. 1°

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Radiographic residual stress measurements


Determination of residual stresses, texture, depth profiles and phase analysis (in particular residual austenite) using stationary x-ray diffractometers:

Metals, ceramics, various phases

Depth profiles through electrolytic erosion

Lateral resolution up to 100µm


Residual stress measurements using mobile x-ray diffractometers:

Metals, ceramics, various phases

Large samples and at the customer’s site

Depth profiles can be obtained at the customer’s site by electrolytic erosion using a mobile instrument

Lateral resolution up to 300µm


Residual stress mapping on measurement tracks in the case of complicated surface geometry using a robot diffractometer:

Metals, ceramics, various phases

Lateral resolution up to 300µm can be obtained

Automated measurements at multiple measurement points of large components where surface geometry is complex


Determination of residual stress depth profiles using hole-drilling devices:

Residual stress depth profiles with depths from approx. 0.04 mm to approx. 1 mm

Not nondestructive since a small hole is drilled in the material

Hardness of material up to 55 HRC (greater hardnesses on request)

Measurements can be made on the surface using radiographic techniques

Measurements can be made at the customer’s site and on large components


Measurement of residual stress depth profiles via the ring core method:

Residual stress depth profiles for depths up to 5 mm

Hardness of material up to 55 HRC

Not nondestructive since a circumferential groove is milled into the material

Measurements can be made on the surface using radiographic techniques

Measurements can be made at the customer’s site and on large components

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Characterization of granulates and their behavior during processing


Flow properties examined with hopper outflow experiment

Angle of repose measured with repose angle analyzer

Fill level measurement

Compaction behavior, wall friction using matrix fitted with instruments

Sinter shrinkage using load dilatometer

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