Relationship between rupture stress and microstructure parameters of plastically deformed heat-resistant steel

Abstract

620.187.3 and I. B. OkipnyiThe paper addresses the influence of plastic prestraining in tension and combined tension at 150 and 350°C on the rupture stress in 15Kh2MFA steel upon heat treatment that simulates irradiation embrittlement of materials in a WWER-440 type reactor towards the end of its lifetime. The dependence of rupture stress on the dislocation density in the material upon plastic prestraining is studied. It is found out that as the plastic prestraining in tension and combined tension grows, the dislocation density within small-angle boundaries increases and thus results in a larger rupture stress. An increase in rupture stress in the case of prestraining at 350°C is more intensive than that at 150°C. We analyze the microcrack nucleation and growth micromechanisms in 15Kh2MFA steel during tensile plastic deformation and discuss the effect of the material substructure on the microcrack arrest.

INFLUENCE OF LONG-TERM OPERATION ON THE STRUCTURE AND IMPACT TOUGHNESS OF THE 09Mn2Si PIPE STEEL

“…2 a). It agrees well with the results of TEM observations showing low dislocation density at the beginning of plastic flow [5]. Specimens of both types exhibit similar values of the lower and upper yield stresses and ultimate tensile strength.…”

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“…Another quite bright effect is the intragranular shear of grains (slippage, turning, climbing), which is observed during delineation of boundaries and the formation of the surface cyclic loading [16]. This shear of grains causes a clearer microrelief.…”