UDC 538.9:621.785.6

Mukazhanov Ye.B.¹

Telebayev Ye.Ye.²

Takenova G.D.³

Tynaliev Bauyrzhan⁴

¹ Doctoral Student, PhD, Associate Professor, Academy of Economics and Law, Zhetysu State University. I.Zhansugurov, Taldykorgan, Kazakhstan

Taldykorgan Polytechnic College

² Taldykorgan Polytechnic College

³ PhD, Associate Professor, Taldykorgan Polytechnic College

⁴ Taldykorgan Polytechnic College

Taldykorgan, Kazakhstan

Structural phase transitions in the dispersion-hardening alloys at high-AGING 47HNM

Chromium-nickel alloy used in the manufacture 47HNM uprugochuvstvitelnyh elements of various devices and machines, and different from other precipitation-hardening alloys significantly higher corrosion resistance in harsh environments. [1] Additionally 47HNM alloy is used as the material for structural components of nuclear and thermonuclear reactors with water coolant. [2]

Earlier, in [3] shows the effect of hardening temperature, hold time for hardening and cooling rate on the phase-structural state of the alloy 47HNM. So, after tempering at temperatures 900-13000S 47HNM structure of the alloy is two-phase, consisting of grains of γ-matrix and α-particle phase. With increasing exposure time is set for hardening solution hardening α-phase grain growth of the matrix alloy and increase assorted changes in the nature of the grain boundaries [3]. Grain growth in the alloy 47HNM very depressed because of the presence of excess α-phase, which inhibits the migration of boundaries during recrystallization. Change in the structural-phase state of the alloy under different conditions 47HNM quenching produces the mechanical properties [4].

Because, precipitation-hardening alloys used mainly after treatment, which includes quenching and aging, further interest research the effects of aging on the structure and properties of the alloy 47HNM, which are addressed in this article.

Experiment. Subjects - alloy 47HNM industrial manufacturing and standard chemical composition (47%-Cr, 5%-Mo, stop. - Ni).

Structural-phase state of the samples was investigated by optical (NEOPHOT-21) and electron (EM 125K) microscopes. Thin sections for metallographic studies polished and etched electrolytically in 10% strength acetic chlorine electrolyte. The samples for electron microscopy in the form of discs were prepared by jet electropolishing and by thinning of the foils.

Results and discussion. Typical microstructures corresponding to different stages of aging in the temperature range 800-11000S shown in Fig. 1-4. After aging at 800°C throughout the volume of the material takes place with the release of the intermittent collapse of α-phase chromium-based BCC.

When there is a change of dispersion structure, increase mezhlamelnye distance grows thick slats. At the front of the reaction observed the initial stages of coagulation blades punctuated decay (Fig. 1b), which leads to a drop of the strength properties of the alloy. The migration of the reaction front is at a significant segment of the boundary, so while there are a lot of plates α-phase, moving perpendicular to the growing edge. Increasing the surface of the reaction front leads to new particles between the growing blades. Are in the process of growth takes the form of plates or rods. The origin of the particles can occur alone or branching of existing ones, since no strict correspondence between the crystallographic and the initial release of the matrix.