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

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2. Peculiarities of mechanical properties distributions The available baseline experimental information on MMP characteristics and their dispersal for 15H2NMFA steel (C-0,15%; Cr-2%; Ni-1%; Mo-0,6%; V-0,11%) Makhutov et al. (1989) was acquired on a standard trial basis for laboratory specimens under static loading (up to 30 specimens) at temperatures 20 o С и 350 o С and is presented in the Tables 1 and 2. The empirical distribution functions for abovementioned mechanical properties are presented in Fig. 1. These functions are primary ones for all following calculation procedures. After statistical data processing in accordance with Stepnov and Zinin (2016) it was established that MMP characteristics σ в, σ т, ψ k , S k are described well by a near normal distribution (Fig. 1); which was thereafter taken as a basis for calculating these design characteristics with specified probability P for all temperature values.

Fig. 1. Distribution functions of main mechanical properties steel 15H2NMFA at normal temperature: 1 – δ, 2 – σ 0.02 , 3 – σ 0.2 , 4 – σ B , 5 – ψ k , 6 – S k .

Table 1 also features the numerical values of noted characteristics are given also for low boundaries of dispersal at Р=0.05 and Р=0.01. While analyzing the Table 2 the relatively subtle difference of variation coefficients for ultimate strength σ в and yield stress σ т at room temperature can be noted. The ultimate plasticity variation coefficient for ψ k has the minimal value. The abovementioned data on dispersion characteristics of standard mechanical properties indicate the stability of 15H2NMFA steel production process. The dispersion of the same characteristics increases considerably (by a factor of up to 1.6…2) at 350 o С.