Determination of equilibrium transformation temperatures Ae(3) and Ae(1) for low-carbon steels using the in situ high-temperature X-ray diffraction technique

作者：Equihua F^*; Salinas A

来源：Powder Diffraction, 2010, 25(1): 31-37.

DOI：10.1154/1.3308411

• in situ X-ray diffraction
• equilibrium transformation
• HTXRD
• austenite
• ferrite

This paper describes a method to determine the equilibrium transformation temperatures in low C steels using the in situ high-temperature X-ray diffraction technique. The samples were heated and then cooled from 1000 to 720 degrees C in a stepwise manner decreasing to -10 degrees C. Austenite and ferrite fractions were determined by a quantitative method using the integrated intensities of austenite (111)(gamma) and ferrite (110)(alpha) peaks from X-ray diffraction patterns. The effect of the temperature on interplanar d spacings of (111) and (110) crystallographic planes was determined using 2 theta maximum positions of the austenite (111)(gamma) and ferrite (110)alpha peaks. The equilibrium transformation temperatures were determined to be Ae(1)=720 degrees C and Ae(3)=950 degrees C. The results are in excellent agreement with those obtained by dilatometric analysis and Thermo-Calc phase diagram simulation software. In addition, the results were supported by microstructural observations: the formation of thin ferrite films (5-10 mu m) was observed at temperatures near to experimental Ae(3).

• 出版日期2010-3