“…[6][7][8][9] Therefore, the widely prevailing criterion identifying the type of martensite under optical microscope is that the packet or equilateral triangular martensite is lath martensite. [1][2][3][4][5][6][7][8][9] Recently, the authors [10][11][12][13] have studied in depth on the apparent morphologies of fine plate martensite in medium and high carbon steels, and found that when austenitizing temperature is higher, the chemical composition is homogenized, grains are coarsened and crystal defects are diminished, which in turn reduces the obstruction to directional nucleation and growth of martensite, fine plate martensite will become a regular arrangement, appearing as packetlike or equilateral triangular morphologies. Such martensites in medium and high carbon steels were named as Fibre Martensite 10,11) or Packet Plate Martensite by the authors.…”