Key Engineering Materials Vol. 839

Abstract: This work is devoted to the study of the influence of technological parameters of electrolytic-plasma surface quenching (EPQ) on the structure and surface properties of samples of bandage steel 2. In the electrolytic-plasma treatment, we performed the cathode mode in an electrolyte containing an aqueous solution of 20% carbamide (NH₂)₂CO and 20% sodium carbonate Na₂CO₃, on the installation of EPO with appropriate technological processing conditions. According to the electron-optical, X-ray phase studies, the phase composition of the steel after the EPQ was determined this differs from the initial one by the formation of cementite and iron oxides on the surface of the samples. It is established that the microhardness of the bandage steel 2 after the EPQ during heating for 4 seconds increases 2.4 times in comparison with the initial state.

Abstract: The article discusses the use of polymer composite materials in the manufacture of ship ventilation pipelines. In this article, the author gives the features of manufacturing technology of ship pipeline production with different designs from composite materials.

Abstract: The work is dedicated to the development of the optimal technological process for the manufacture of hot stamping dies and die casting molds made of steel grade 4X5MF1С, in order to ensure the required performance characteristics. The mode of hardening heat treatment of this steel grade was established, which allows to recommend it as a heat-resistant structural material for metal products with the required yield strength σ_0.2 within 750 to 1000 MPa.

Abstract: Selective laser melting (SLM) is a manufacturing technology of metal parts of any shapes with target mechanical properties by means of laser melting. This paper discusses the effect of SLM parameters: laser output power, laser movement velocity, scanning pitch and preheating temperature of a powdered material on surface formation mechanism, namely, its physical configuration when melting cobalt-chromium-molybdenum powdered material Со28Cr3Mo. The study points at structural differences of melted surfaces even under identical process parameters. Several types of surface formation are identified, e.g. homogenous melt, coagulated particles, and shapeless particles. Vapor pressure, Marangoni effect, and heat effect of a melted powder are stated to be key reasons for rough surface. This research is of high importance for understanding the effect of SLM parameters on formation of a target quality surface, positive stability and repeatable accuracy of the process.

Abstract: Selective laser melting (SLM) is thought to be a prospective manufacturing technology of complex metal components. Formation of coagulated particles when melting is reported to be an important factor for target mechanical properties of the end product. This paper discusses the effect of SLM parameters, including laser output power, laser movement velocity, preheating temperature of the powder, laser beam diameter on the mechanism of forming coagulated particles in melting cobalt-chromium-molybdenum powdered material. The study shows that a rise of power to 60 W at a scanning velocity 6 mm/s causes coagulated particles to expand to 350 μm; that is far bigger than a size of powder in as delivered state (90 μm). The work investigates the effect of mechanical activation of cobalt-chromium-molybdenum powder on dimensions of coagulated particles. The research data can be applied to the improvement of up-to-date optimization approaches to manufacturing process parameters in SLM technology.

Abstract: This article presents the results of experimental studies aimed at improving the physicomechanical properties of effective hollow ceramic stones using various technological methods that will disperse, homogenize and structure the ceramic mixture by introducing industrial waste with high alumina content, dispersed reinforcement, and also mechanical activation of the molding material, accompanied by the fragmentation of clay particles to a colloidal degree of dispersion, allows eliminating the aging process. The main molding characteristics of the investigated mixtures were determined, X-ray phase analysis of ceramic masses and a shard of the control composition was performed and after dispersion, activation modes were worked out, strength characteristics of ceramic samples made of dispersed clay raw materials were determined.

Abstract: The possibility of application for steel alloying with vanadium of the technology based on restoration of vanadium from oxides of converter vanadic slag with use of the reducers (carbon of a koksik and silicon of ferrosilicium) having low cost and a purge gaseous nitrogen with high coefficient of extraction of the alloying element is shown.

Abstract: The problem of enrichment and dephosphorization of poor manganese ores for receiving the low-phosphorous alloys necessary for smelting of steel of low-temperature reliability is considered.

Abstract: We propose a flow diagram for processing ferroalloy production waste, such as silicothermic slag from manganese metal, as well as wet and dry powder of cleaning gas from ferroalloy furnaces that smelt manganese alloys. We experimentally determined the parameters for intensifying the calcium chloride method of enriching ferroalloy production waste, which resulted in a manganese extraction rate of 78-86%, with high-quality manganese concentrates. We present the results of studies related to the use of high-quality concentrates to dope steel with manganese, when processing it in a bucket, and smelting manganese metal via the aluminothermic method.

Abstract: The article is devoted to the study of the characteristics of shock-wave processing of powder mixtures capable of an exothermic reaction of the synthesis of metal-ceramic materials. Experiments on shock-wave initiation of synthesis in systems based on Ti-B and Ti-C with 10% and 20% Ni content were carried out. Explosive loading was carried out by oblique throwing of a steel drummer with speeds of 1000 m / s and 1500 m / s. X-ray phase analysis of synthesis products showed the presence of TiB₂ diboride and TiC carbide in the nickel bond. The significant role of the mechanical activation of powder mixtures in increasing the sensitivity of SHS-mixtures to shock-wave loading is shown.