{112} 〈111〉 Twins or Twinned Variants Induced by Martensitic Transformation?

Twinned substructure in lath martensite was induced in the interstitial free (IF) steel via a high pressure thermal cycle (heating up to 1100 ℃ and holding for 30 min, cooling at 10 ℃/s to room temperature under a pressure of 4 GPa). Experimental observations and theoretical simulation confirm that the twinned substructure has the origin related to the twinned variants rather than the bcc {112} 〈111〉 twins, while extra diffraction spots were caused by crystal overlapping rather than any extra phase. The differences in crystallography and electron diffraction behavior between twinned variants and {112} 〈111〉 twins were discussed in detail.