[en] The structure of a cluster of martensite crystals has been investigated in quenched from high temperatures structural steels 45KHNMFA and 18KHNVA and model Fe-Ni-alloys--steel analogues. It is shown, that the steel structure contains two morphological types of martensite: scaly(twinned) and ''rack''-type crystals connected in the form of a block. The three versions of blocks containing scales of (225)sub(A), (252)sub(A) and (522)sub(A) habit planes and racks of (111)sub(A) habit plane form a cluster including six orientations of martensite. The distribution of residual austenite along the block boundaries (but not along the racks) and the homogeneity of a shift deformation of transformation within the range of a rack set indicate that a rack is not an independent structural unit of the martensite phase. A mechanism of the formation of racks with small angle boundaries which are predominantly the boundaries of torsion is proposed