PSI - Issue 20

N.A. Makhutov et al. / Procedia Structural Integrity 20 (2019) 63–74 N. A. Makhutov and V. V. Zatsarinnyy / Structural Integrity Procedia 00 (2019) 000–000

69

7

�� � � �� � � � т� �� т � тт ∗ �� т � � � �

(6)

On a first approximation the dependence of n ψ on σ 0,2 / σ в can be assumed to be linear � � ���� � ��� � � ��� � в � �����

(7)

According to the expressions (1…7) the calculations of characteristics σ т , σ в , ψ k and S k for 15H2NMFA steel at the temperatures +80, +350 and -85 o С have been calculated. The data of experiments at Т = Т 0 = 293 К were used as initial calculations. Available experimental data at 20 and 350 o C were superimposed on calculation curves of these characteristics (Fig. 4).

Fig. 4. Comparison of experimental and calculated characteristics of mechanical properties at different temperatures.

The comparison of average (at the probability P=50%) experimental and calculation MMP characteristics at the temperatures of 20 and 350 o C is presented in the Table 4. In this Table the Δ relative errors for specified calculation values of the characteristics defined at these temperatures are also given with corresponding experimental characteristics. It is apparent that the smallest deviations from average values (in relation to calculation values) are achieved at room temperature: -12% for S k and -3.2% for σ т ; it contributes to the safety factor. The deviations of other characteristics grow as the temperature increases and constitute +5,8% for σ в , +9,9% for σ т , +17% for S k and + 20% for ψ k . In the Fig. 4 the calculation characteristics computed according to the aforementioned procedure are shown for temperatures +80, +20 and -85 o С at calculation curves for σ т , σ в , ψ k characteristics.