You wish to measure the austenite retained in your steels by DRX according to the ASTM E975-22 standard
What is retained austenite in steels?
Austenite is a crystalline phase of iron (and some steels) that appears when the steel is heated to high temperatures.
- It is a face-centered cubic (FCC) structure of iron that can dissolve a large amount of carbon.
- It typically exists in a temperature range between 723°C and approximately 912°C (depending on the steel's composition).
- Upon cooling, austenite transforms into other phases (martensite, ferrite, pearlite, etc.), unless it remains trapped: this is called retained austenite.
Why measure retained austenite?
Retained austenite is a metastable phase present in certain quenched and tempered steels. Its percentage directly influences:
- Mechanical performance (hardness, toughness, wear resistance).
- Dimensional stability of parts in service.
- Fatigue and impact resistance behavior.
Excess retained austenite can lead to deformation or loss of performance, while precise control ensures the quality and reliability of your steels.
The solution: X-ray diffraction (XRD)
The ASTM E975-22 standard defines the method for quantifying retained austenite using X-ray diffraction (XRD).
This technique allows for:
- Direct quantitative analysis of crystallographic phases.
- Non-destructive measurement, suitable for finished parts.
- High accuracy, even for low levels (<1%).
The FILAB laboratory measures the austenite retained in your steels according to the ASTM E975-22 standard.
Why choose FILAB for measuring retained austenite in steels?
Equipped with a state-of-the-art analytical park and a team of experts dedicated to metallurgical analysis, the FILAB laboratory supports manufacturers in resolving their problems related to steel analysis.
The principle of XRD in the measurement of residual austenite according to ASTM E975-22
XRD analysis is a powerful analytical technique based on the phenomenon of X-ray diffraction by the atoms of a material.
When X-rays encounter the crystalline structure of a sample, they are scattered at specific angles based on the arrangement of atoms within the material. By measuring the intensities and diffraction angles, it is possible to determine the crystal structure and phases present in the sample, including retained austenite.
Our other steel analysis services
Metallographic examination of steel
Weld analysis on steel
Study of fracture surfaces on steel
Study of ageing (corrosion, surface alteration, etc.) on steel
Thickness measurement of steel
Study of corrosion resistance on steel
Analysis and characterization of steel surfaces (roughness, defects, etc.)
Analysis Alloy composition
Study of microstructures steel material
FAQ
Retained austenite is a crystalline phase of iron that can persist after heat treatment of steel (hardening, tempering). Its quantity directly influences the hardness, dimensional stability and mechanical strength of the material.
Automotive & aeronautics industries: inspection of critical parts (gears, shafts, bearings, etc.).
Nuclear & energy: securing components under harsh conditions.
Medical & implantable devices: mastering the microstructure of metal alloys.
Subcontractors in heat treatment & steelmaking: process validation.
- Austenite gives steels good ductility (the ability to deform without breaking).
- Its transformation into martensite during quenching is the source of the hardness of hardened steels.
- Too much retained austenite can cause problems (dimensional instability, drop in hardness), while careful control can improve certain properties (impact strength, impact resistance).
In summary, austenite is a specific form of iron that plays a key role in the heat treatment and performance of steels.
Ensure compliance with specifications and industry standards.
Optimize heat treatments to achieve expected mechanical properties.
Avoid in-service defects: deformation, cracking, and loss of hardness.
The measurement is carried out according to the international standard ASTM E975-22, which defines the method for quantifying retained austenite by X-ray diffraction.
Non-destructive: the analyzed part is not altered.
High precision: low levels (<1%) can be detected.
Applicable directly to finished parts.
