Issue 49

S. Smirnov et alii, Frattura ed Integrità Strutturale, 49 (2019) 201-211; DOI: 10.3221/IGF-ESIS.49.21 205 where ∆τ i is soaking time at constant temperature (s); ∆ε i is creep-induced specific elongation at the i-th step of temperature variation. Figure 4 : Procedure of experimental data processing The steady-state creep activation energy Δ H i at the i -th step of heating is calculated by the formula found in [45],              1 ln i i i R H , [kJ/mol], (3) where R = 8.3144598 10 -3 [kJ/(mol·K)] is the universal gas constant. The results of calculations by Eq. (3) is averaged for each material and environment tested. In order to determine conventional creep strength T / . 120  , the heating temperature T at which 1 hour soaking was accompanied by permanent elongation of 0.2% at specified nominal tensile stress σ was recorded. R ESULTS he experimental results on the determination of creep rate at the steady-state stage are demonstrated in Figs. 5 and 6. To describe them analytically, we use the well-known exponential dependence found in [45]          exp n H A RT , [1/s] (4) where А and n are empirical coefficients. T