Temperature Dependences of Elastic Young’s Modulus and Internal Friction of 12% Chromium Ferritic-Martensitic Steels EK-181 and EP-823 with Different Heat Treatment Modes

The elastic (Young’s moduli) and relaxation (amplitude-independent internal friction) properties of ferritic-martensitic 12% chromium steels EK-181 (low-activated) and EP-823 depending on their heat treatment modes (THT—traditional, CHT—combined) have been investigated by the method of dynamic mechanical spectroscopy in the low-frequency range (0.5–30.0 Hz) and the temperature range of 25–400°С. The temperature, frequency, and amplitude dependences of Young’s moduli and internal friction have been determined. Frequency and amplitude independence of elastic moduli is observed. The values of Young’s moduli depend on their modes of heat treatment of steels (THT, CHT) and for EK-181 steel is always higher than for EP-823 steel. The temperature dependences (spectra) of internal friction in steels for different modes of their heat treatment and at different frequencies almost monotonically increase with increasing temperature. Relaxation peaks are practically absent (within the measurement accuracy), which determines the practical absence of solid interstitial solutions (C, O, N) in the studied steels.