Lost pattern complex composition effect on steel casting structure and properties

One of the ways to produce high-quality castings at relatively inexpensive costs is lost foam casting. However, the existing problem of surface carburization due to the burnout of the polystyrene pattern and general contamination of the near-surface layer is one of the factors that hinder the widespread use of this casting method. In order to minimize carburization, it is proposed to use a complex pattern composition. The results of studying the effect of the pattern complex composition and the technological parameters of manufacturing the “Through Cover” casting for the ingot purity and structure are presented

Studying of properties and microstructure of 30 CrMnV9 steel on wear resistance

The properties and microstructure of 30 CrMoV9 steel after its treatment with ferronickel and ferromanganese with the aim of increasing the content of nickel and manganese in steel were studied. After the trial smelting, the samples were tested in four parameters: hardness, ultimate stress limit, wear resistance, and toughness. Experimental studies have shown that changing the composition of steel with increasing the nickel content up to 0,5 – 0,7 % and manganese up to 1,5 – 1,8 % leads to increasing strength, hardness and wear resistance of steel with slight decreasing its toughness

Studying microstructure of heat resistant steel deoxidized by barium ferrosilicon

The paper examined the nature and distribution of non-metallic inclusions in the heat-resistant steel 12H1MF (0,12 % С, 1 % Сr, 0,5 - 0,6 Mo, 0,5 % V), ferrosilicobarim. As a reference, used by steel, deoxidized silicon. Melting was carried out in a laboratory, research-metallic inclusions, their shape and distribution, pollution index were studied according to conventional methods. Studies have shown that ferrosilicobarim deoxidation in an amount of 0,1 - 0,2 %, reduce the overall pollution index of non-metallic inclusions and change the nature of their distribution

Nanomodifier effect on structure and properties changes of heat-treatable steel

The paper considers the effect of titanium carbide nanopowder (hereinafter referred to as the nanopowder material, NPM) on the structure and properties of medium-carbon heat-treatable steel containing vanadium, niobium, molybdenum and chromium. The titanium carbide nanopowder with dispersion of 80-90 nm in the amount of 0,08 % was introduced into steel before casting. After heat treatment, the prototypes were tested for hardness and wear resistance. The results show that in the experimental samples these properties are improved, which is associated with changes in the structure. The metallographic analysis of the structure (interstitial phases) was performed using ThixometPro software (Russia). In the analysis such parameters as the average size and the perimeter of interstitial phases, their shape and total relative occupied area were estimated. The results show that introducing the NPM leads to decreasing the size of interstitial phases and increasing the sphericity of the shape. Such structural changes increase hardness and wear resistance

Production of technical silicon and silicon carbide from rice-husk

In the article there are studied physical and chemical properties of silicon-carbonic raw material – rice-husk, thermophysical characteristics of the process of rice-husk pyrolysis in nonreactive and oxidizing environment; structure and phase composition of products of the rice-husk pyrolysis in interval of temperatures 150 – 850 °С and high temperature pyrolysis in interval of temperatures 900 – 1 500 °С. There are defined the silicon-carbon production conditions, which meet the requirements applicable to charging materials at production of technical silicon and silicon carbide

Iron loss in high-power arc steelmaking furnaces

There is considered the power operating mode of a high-power arc steelmaking furnaces (ASMF) in the period of the flat bath. It is revealed that electric energy is mainly spent for heating and overheating the foamed slag. Heat transferring from slag to metal is carried out by the convective agitation of the bath. For agitation there is used intensive purging of the bath with oxygen that causes increased iron losses with the running foamed slag. There are noted the negative points of working with the foamed slag. It is recommended to expand R&D in the field of optimizing the power operating mode of high-power ASMF

Chromium-nickel cast iron composition effect on properties and graphitization process

The paper considers the cast iron based on nihard-2 composition effect on the properties and process of graphitization. It is shown that changing the Cr:Si ratio equal to 2:1 leads to the development of the graphitization process, as a result of which lamellar graphite appears in the structure. Subsequent modification leads to changing the shape of the graphite into the nodular one, which leads to some decrease in hardness but increases resistance to abrasive wear by about 20-25 %

Studying the properties of refractory products manufactured by two-stage pressing under industrial conditions

The article deals with studying the properties of refractory masses made by two-stage pressing under industrial conditions in order to increase strength and slag resistance of chamotte bricks due to increasing density by ensuring uniform porosity throughout the volume of the product. Changing porosity when firing is less significant than changing porosity when pressing, therefore, the structure of the product is corrected by the initial mass of components

Studying the chrome-nickel cast iron structure and properties after modification on industrial samples

The paper presents the results of studying the structure and properties of chrome-nickel cast iron samples obtained under production conditions. Cast iron with a given ratio of silicon and chromium smelted in an industrial arc furnace was treated with titanium carbide followed by modification with a complex modifier containing (Scanning electron microscope). As a result of the composition adjustment and appropriate processing, a mixed structure was formed represented by an austenite-ledeburite matrix, iron, chromium and titanium carbides and a small amount of free graphite, both lamellar and spherical. This structure is characterized by higher wear resistance and impact resistance compared to Nihard-2 but at the same time it shows lower hardness

The corrosion resistant coating with halloysite nanoparticles

The process of application of coating on metal surfaces is described in this article. The composition with 100 % corrosion preventing substance + 42,5 % acetone + 10 % halloysite was recognized as the most appropriate for coating, and it provides the best corrosion resistance of hydraulic pump details. The impellers of circulation pumps for water delivery in heating system fail after 5 - 6 months because of the galling of work flutes, as water doesn’t pass through the chemical purification. After applying corrosion resistant coating with halloysite the lifetime of impellers increases. The essence of which is dipping the impeller into hydrochloric acid with 24 hour keeping in it, then it is dried in dryer up to 4 hours. The lifetime of this impeller increases 1,8 fold and it was approximately 9 months