Double twist torsion testing to determine the non recrystallization temperature

Area of Science:

• Materials Science
• Metallurgy
• Mechanical Engineering

Background:

• Recrystallization behavior is crucial for controlling material properties during thermomechanical processing.
• Accurate determination of the non-recrystallization temperature (Tnr) is essential for optimizing processing parameters.
• Traditional methods for Tnr determination can be time-consuming and may not fully capture complex deformation histories.

Purpose of the Study:

• To develop and validate a novel double-twist torsion testing technique for assessing recrystallization behavior.
• To experimentally determine the non-recrystallization temperature (Tnr) of 316 stainless steel using the new method.
• To compare the efficacy of the double-twist torsion test against established methods like double-hit compression and multi-step hot torsion testing.

Main Methods:

• A double-twist torsion testing apparatus was employed.
• 316 stainless steel was used as the exemplar material.
• Fractional softening measurements were utilized to relate Tnr to the extent of austenite recrystallization.

Main Results:

• The double-twist torsion test yielded average Tnr values comparable to those obtained from multi-step hot torsion testing.
• A partially recrystallized microstructure was observed near the calculated Tnr across all tested methods.
• The new technique successfully accommodated multiple deformation and recrystallization steps within a single specimen.

Conclusions:

• The double-twist torsion test provides a reliable method for determining Tnr and quantifying austenite recrystallization.
• This technique offers an advantage by integrating multiple deformation steps and relating Tnr to fractional softening.
• The developed method enhances the understanding of austenite recrystallization during thermomechanical processing.