INFLUENCE OF NON-METALLIC INCLUSIONS ON THE CORROSION RESISTANCE OF STAINLESS STEELS IN ARC SURFACING

The influence of non-metallic inclusions on the corrosion resistance of stainless steel of the austenitic-martensitic class, deposited in one layer with flux-cored wire under the flux by the arc method in the mode of stationary and pulsed arc burning, has been studied. In the latter case, the wire feed impulse was 0.5 and 0.7 Hz. The selected surfacing conditions, with both methods of the process, contribute to the formation of non-metallic inclusions of complex composition and structure in the deposited metal, including those containing calcium and its compounds with other elements, which are classified as corrosive, accelerating the occurrence of corrosion phenomena.

Influence of the Structural State of Titanium Alloy on the Depth of Penetration of Ions during Implantation

The article presents the results of the influence of the structural state of titanium alloys VT1-0 (α-alloy), VT20 (pseudo-α-alloy), VT6 (α + β) -alloy of the martensitic class) and VT15 (pseudo-β-alloy) on the penetration depth ions of nitrogen, aluminum, copper and the cathode of the alloy 50% Cu – 50% Fe. It is shown that the structural class of titanium alloys selected for the study, when exposed to ion implantation by both gases and metals, does not significantly affect the depth of their penetration.

Improvement of the Turbine Blade Surface Phase Structure Recovered by Plasma Spraying

This paper presents the results of research on the construction, technological parameters and criteria that control the process of formation of optimal phase structure of austenitic- and martensitic-class material for steam turbine blades. The hypothesis that the established correlation could increase the quality of blade recovery and its resistance against dynamic and vibrational loads was proved. The efficiency of the developed implantation method for the recovery of steam turbine blades was demonstrated. The optimal technological parameters of the process of laser plasma recovery were established empirically, allowing the development of the system for the fine tuning of the phase composition of austenitic- and martensitic-class steel.

Influence of Heat Treatment Technologies on the Structure and Properties of the Corrosion-Resistant Martensitic Steel Type AISI 420

One of the methods for increasing the complexity of chromium steel properties of martensitic class AISI 420 is the use of an optimal heat treatment mode. The steel of martensitic class AISI 420 has high resistance in atmospheric conditions (except for the sea atmosphere), in the river, and tap water. It is widely used in power engineering, in cracking units with a long service life at temperatures up to 500 °C, for furnace parts. Additionally, it is used in the following fields: the production of turbine blades, working in conditions of high temperatures and parts of increased plasticity, subject to shock loads, for products exposed to atmospheric precipitation, solutions of organic salts and other slightly aggressive environments; production of fasteners; production of parts for compressor machines operating with inert gas; production of parts operating at low temperatures in corrosive environments; production of parts for aviation purposes. It is shown that the optimal mode of heat treatment for a maximum hardness of 40 HRC is quenching at a temperature of 980 °C with cooling in oil and tempering at a temperature of 200 °C with air cooling. With an increase in the tempering temperature from 200 °C to 450–500°C, the impact strength does not change much. Tempering at higher temperatures leads to the intense weakening of the steel. Simultaneously, a decrease in the impact strength is observed, the minimum value is reached at a tempering temperature of 550 °C. With an increase in the tempering temperature to 700 °C, the impact toughness increases, but the steel’s hardness sharply decreases at such temperatures. Keywords: hardening, tempering, hardness, toughness, mechanical properties, chromium carbide.

Mastering of seamless pipes production from martensiticclass stainless steel of 13Cr grade type at the JSC “VTZ” TPA 159–426 pipe mill

Mastering of offshore deposits of hydrocarbons require application of new types of pipe products, capable to effectively work under conditions of constant impact of aggressive media. In this connection new tasks arose to produce seamless hot-deformed pipes made of martensitic class stainless steels with increase chrome content. Mastering of such pipes production is connected with necessity to overcome a series of technological problems. The problems are stipulated by metal structure peculiarities, appeared in low plasticity and narrow temperature range for hot deformation, increased inclination to defects formation in the rolling process, as well as more intensive wear of rolling instrument, in particular of that of piercing mill. Main stages of seamless pipes production mastering, made of type 13Cr steel grades at TPA 159–426 line with TPZ-3 continuous mill of JSC “Volzhsky Pipe Plant” presented. The complex of measures for the noted problems overcoming, including semi-product type selection, piercing mill rolling instrument calibration change, as well as deformation regimes and other measures presented. The elaborated complex of measures allowed providing of pipes manufacturing of necessary quality for PAO “Gasprom” demand as per TU 14-3Р-129–2015 specifications.

Engineering procedure in electron-beam welding of blade packet for steam turbines

A technology for manufacturing a steam turbine blade packet made of heat-resistant high-alloy hard-to-weld steel of a martensitic class is offered. The advantage of electron-beam welding use at the assembly of a blade packet instead of a common electric arc welding method in protective environment is described. A technological tooling specially designed essential for welding process automation is considered. There are shown results of laser scanning a blade packet geometry with the aid of NikonMetrology MCAx40+ coordinate measuring arm with the further computer analysis of results obtained in applied Focus software which has shown that thermal deformations are within the limits of a tolerance for the mentioned operation and exclude completely further processing. The application of electron-beam welding at manufacturing a blade packet allows increasing assembly quality, decreasing defects and cost price of an engineering process.