Chemical-heat treatment of 08Kh18N10T steel to improve its performance

Effect of liquid boriding on the structure and properties of 08Kh18N10Т steel is studied by metallographic studies. The dependence of the phase ratio in the boride layer on holding time is established. Corrosion resistance tests in 5 % saline solution and in salt spray chamber are performed. It is shown that the corrosion resistance of 08Kh18N10Т steel practically does not deteriorate after liquid boriding.

Experimental studies into the performance of the lead coolant axial pump wet ends to justify main circulation pumps for the HMLC reactor plant circuits

The paper presents the results of the studies to justify the design solutions for the main circulation pumps of the heavy liquid-metal cooled reactor plant circuits. A substantial difference has been shown in the performance of pumps for the heavy liquid-metal coolant transfer. The studies have confirmed the qualitative difference in the cavitation performance of coolants, the state of the gases and vapors they contain, the influence of supply and discharge devices, and the effects of the impeller blade section performance and geometry and the hub-tip ratio on the pump performance. The studies were performed based on NNSTU’s lead-cooled test facilities with the coolant temperature in a range of 440 to 550 °C and the coolant flow rate of up to 2000 t/h. The outer diameter of the impellers and the straightening devices was about 200 mm, and the thickness of the flat 08Kh18N10T-steel blades was 4.0 mm and that of the airfoil blades was up to 6.0 mm. The pump shaft speed changed in a stepped manner from 600 rpm to 1100 rpm after each 100 rpm. The studies were conducted to justify the engineering and design solutions for pumps as applied to conditions of small and medium plants with fast neutron lead cooled reactors currently under investigation at NNSTU (BRS-GPG). The experimental results can be recommended for use to design other HLMC transfer pumps.

On corrosion resistance of nitrogen-containing steel in abrasion conditions

This work presents tests’ results on the corrosion and erosion resistance of nitrogen-containing steel 04Kh20N6G11M2AFB in comparison with steel 08Kh18N10T, AB2-2 and VT1-0 titanium alloy. It is difficult to determine steel wear resistance against ice with abrasive (20%) due to the rapid melting of ice. It has been shown that the most effective methodology for assessing the corrosion-erosion resistance to simultaneous impact of abrasive and a 3.5% solution of NaCl to the metallic surface consists in the determination of the repassivation rate of the oxide film. It was found that the electrochemical potential of 04Kh20N6G11M2AFB stainless steel recovers 1.5 times faster than that of 08Kh18N10T steel, so it is very promising to use nitrogen-containing steel as a cladding layer of bimetallic alloy for icebreakers belts manufacturing.

STUDY OF THE PHYSICOMECHANICAL PROPERTIES OF 08Kh18N10T STAINLESS STEEL PIPES EXPOSED TO ULTRASOUND UPON DRAWING

The drawing of pipes exposed to ultrasonic vibrations of radial type and their effect on the physical and mechanical properties of the pipe, as well as on the surface quality is studied. The ultrasonic unit with radial vibrations tested under production conditions is used to study the effect of ultrasound on the residual stresses present after drawing, surface roughness, as well as on the physical and mechanical properties and microdefects of 08Kh18N10T steel pipes. Defects and residual stresses before and after drawing under the effect of ultrasound were analyzed by the method of magnetic memory, using the stress concentration meter TSC-4M-16 with an eight-channel scanning device with four two-component sensors (Type 15). It is shown that the residual stresses decreased by more than two times under the effect of ultrasound. The surface roughness after drawing with ultrasound ranged within Ra = 0.087 - 0.092 µm. The physicomechanical properties were studied in tensile tests on an Instron tensile testing machine (SATEC Series). The yield stress qt was 551, the tensile strength qin — 672 MPa. It is shown that the effect of ultra-sound upon drawing pipes made of 08X18H10T stainless steel enhance their quality through reduction of the surface roughness and improved physicomechanical properties.