Meaning
Standard test methods that specify the procedure for determining retained austenite in steels using x-ray diffraction provide a reliable metric for tooling manufacturers. Adhering to ASTM E975 involves measuring the integrated intensities of diffraction peaks from both austenite and ferrite phases. This quantitative analysis allows engineers to verify that heat treatment processes have successfully converted unstable phases into martensite.
The procedure applies specifically to near-randomly oriented crystallite specimens and does not extend to heavily textured or cold-worked alloys.
Measurement Technique
Diffracted beam intensity calculations require precise correction factors to account for the scattering behavior of the metal atoms. Utilizing ASTM E975 ensures that the resulting retained austenite percentage is calculated using standardized atomic scattering factors and lorentz-polarization values.
Tool Steel
Retained austenite in cold-work tool steels reduces the dimensional stability of dies and punches over extended production runs. Applying ASTM E975 allows tooling suppliers to ensure that critical stamp tooling remains dimensionally stable throughout its lifetime.
Structural Integrity
Unstable retained austenite can transform into brittle martensite under the influence of mechanical stress during stamping operations. Using the ASTM E975 protocol to monitor phase composition ensures that tool materials do not experience premature microcracking or catastrophic failure during production.
