A high-Mn austenitic steel, Fe–17.7%Mn–1.5%Al–0.3%C, with an average
grain size of 24 μm that was processed by hot rolling and annealing
at 1423 K for 1 h was used as the starting material. The steel plates of
10 mm thickness were cold rolled at a rolling rate of 5 m/min to various
total strains in the range between 0.2 and 3.0 (final thicknesses of 8 mm
to 0.5 mm). Then, the cold rolled samples were annealed at temperatures
of 673 K, 773 K, 873 K, 973 K and 1073 K for 30 min or 1 h. The
structural investigations were performed on RD–ND sections (RD —
rolling direction, ND — normal direction), using optical microscopy
and electron back scattering diffraction (EBSD) in a Quanta 600 FEG
scanning electron microscope (SEM). The EBSD mappings were subjected
to cleanup procedure setting minimal confidence index of 0.1. The
samples for structural investigations were electro-polished using an
electrolyte containing 10% perchloric acid and 90% acetic acid at a voltage
of 20 V at room temperature. Etching of the samples was carried out
at room temperature using a solution consisting of 2 g potassium disul-
fide (K2S205) and 100 ml cold saturated Klemm I solution
(Na2S2O3 + 5H2O). The volume fraction of fine equiaxed grains, which
were free of any revealed dislocation substructure, was deemed to be
the recrystallized fraction. The size of recrystallized grains was measured
by a linear intercept method as an average distance between
high-angle grain boundaries with misorientations of θ ≥ 15° including
annealing twins. The strain hardening and annealing softening were
studied by Vickers hardness measurements with a load of 3 N
A high-Mn austenitic steel, Fe–17.7%Mn–1.5%Al–0.3%C, with an averagegrain size of 24 μm that was processed by hot rolling and annealingat 1423 K for 1 h was used as the starting material. The steel plates of10 mm thickness were cold rolled at a rolling rate of 5 m/min to varioustotal strains in the range between 0.2 and 3.0 (final thicknesses of 8 mmto 0.5 mm). Then, the cold rolled samples were annealed at temperaturesof 673 K, 773 K, 873 K, 973 K and 1073 K for 30 min or 1 h. Thestructural investigations were performed on RD–ND sections (RD —rolling direction, ND — normal direction), using optical microscopyand electron back scattering diffraction (EBSD) in a Quanta 600 FEGscanning electron microscope (SEM). The EBSD mappings were subjectedto cleanup procedure setting minimal confidence index of 0.1. Thesamples for structural investigations were electro-polished using anelectrolyte containing 10% perchloric acid and 90% acetic acid at a voltageof 20 V at room temperature. Etching of the samples was carried outat room temperature using a solution consisting of 2 g potassium disul-fide (K2S205) and 100 ml cold saturated Klemm I solution(Na2S2O3 + 5H2O). The volume fraction of fine equiaxed grains, whichwere free of any revealed dislocation substructure, was deemed to bethe recrystallized fraction. The size of recrystallized grains was measuredby a linear intercept method as an average distance betweenขอบเขตของเกรนภาพมุมสูง ด้วย misorientations รวมถึงค่าθ≥ 15°การหลอมฝาแฝด ความเครียดการชุบแข็ง และการอบอ่อนอ่อนได้ศึกษา โดยการวัดค่าความแข็งวิกเกอร์สโหลด 3 N
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