Assessing the life of boiler steel on the basis of anomalous thermal deformation of its crystal lattice

In vacuum thermocyclic tests, high-temperature X-ray diffraction patterns reveal anomalous thermal lattice deformation (λ-anomalies) of St10 (Ct10), 08H18N10T (08X18H10T), 12H1MF (12X1MF{cyrillic}), and Di-59 (D{cyrillic}I{cyrillic}-59) 10H13G12BS2N2TS2 (10X13G{cyrillic}12B{cyrillic}C2H2Ts{cyrillic}2) boiler steel within a narrow temperature range. That lattice deformation cannot be explained in terms of familiar phase transitions of types I and II and, according to analysis of the relative integral diffraction-line intensities, is associated with grain-boundary transformations and reorientation of the grains, with consequent modification of the physical and mechanical characteristics and the life of the heat-transfer surfaces.