Assessment of bias errors caused by texture and sampling methods in diffraction-based steel phase measurements

Area of Science:

• Materials Science
• Metallurgy
• Crystallography

Background:

• Advanced high-strength steels utilize metastable austenite for enhanced strength and formability.
• Accurate quantification of austenite phase fraction is crucial for material characterization.
• Existing methods for phase fraction measurement in textured steels are insufficient.

Purpose of the Study:

• To quantify the impact of crystallographic texture on austenite phase fraction measurements.
• To evaluate various X-ray diffraction (XRD) based measurement techniques.
• To identify a robust method for accurate phase fraction determination in textured steels.

Main Methods:

• Numerical experiments simulating X-ray diffraction profiles.
• Variable parameters included texture components, component sharpness, number of peaks, and sampling schemes.
• Phase fraction calculations were performed using simulated data.

Main Results:

• Crystallographic texture, peak selection, and sampling methods significantly bias austenite phase fraction measurements.
• Averaging intensities from multiple peaks or sample orientations introduces substantial errors.
• Hexagonal grid sampling demonstrated minimal bias, proving effective for textured materials.

Conclusions:

• Texture significantly affects phase fraction measurements in steels.
• Standard XRD techniques require careful consideration of texture effects.
• Hexagonal grid sampling presents a reliable approach for accurate austenite phase fraction quantification in textured steels.