Base characteristics of ferritic-martensitic heat resisting steels with 12 % of chrome are parameters of their strength and creep resistance at temperatures of 600 – 750 °С. Steel 16Cr12MoWSiVNbB (EP-823) is considered as the basic material for manufacturing environments fuel rods (TVEL) of a developed reactor with natural safety of BRESTtype. In the literature, there are data about its mechanical characteristics for tensile tests in a range of temperatures of 20 – 750 °С and the limited characteristics of rupture strength. Data on its creep velocity is absent. Laws of creep of steel EP-823 were investigated on metal of three heats with weight of 3 kg. The compression tests at air were applied for cylindrical samples of 5 ÷ 6 mmat temperatures of 600 – 760 °С and stresses of 70 – 310 MPa. The base of compression tests did not exceed 11 hours. The structure after quenching and tempering consisted of tempered martensite and 6 – 12 vol. % of delta-ferrite, the grain size was less 20 μm. It is shown, that the description of creep tests results in double logarithmic (log (σ) – log (έ)) coordinates provides the best concurrence of results of approximation and experiment, than in half-logarithmic (σ – log (έ)). The analysis of parametrical dependences on Hollomon’s PS = (T/1000)[CS – log (έ) and to Larsen-Miller’s PE = (T/1000)[СE – log (σ)] has allowed to find the equations for creep velocity for the set pressure level of 100 – 220 MPa in the form of log (έ) = –19,355 + 9,17 (T/1000) log (σ) and ultimate strength of creep under the set admissions for creep velocity of 0,01 – 1 %/hour in the form of log (σ) = 4,304 – – 0,109 (T/1000) [20 – log (έ)]. Calculations of ultimate strength of creep and creep velocity on pair models and models of Hollomon (Larsen-Miller) give close results, but the preference should be given the second ones as these models consider all three varied factors. Data of control tests under the scheme of a tensile in the same conditions are cited. It is shown, that between results of tests on compression and on tensile at definition of durability characteristics, there is the linear dependence expressed by the equation σ0.2 at compression = 1.3σ0.2 at tensile. At the analysis of creep it has been established, that creep velocity for steel of one grade (09Cr12W3NbB) and for one heat at different type of loading (tensile or compression) have similar values while creep velocities for steel of one grade (EP-823), but of different heats even at one type of loading – compression, can differ substantially.
Creep Rupture Strength of Re and Ru Containing Experimental Nickel-Base Superalloys