DEVELOPMENT OF BIOPLASTICS FROM TAWARO’S ENVIRONMENTALLY FRIENDLY SAGO STARCH

Sustainable bioplastics made from Tawaro sago starch are investigated in the study. This study is motivated by the global need to lessen the environmental impact of petroleum-based polymers and discover greener alternatives. Tawaro sago starch’s amylose concentration, moisture levels, and ecologically friendly qualities are examined in the study. It carefully blends sago starch, glycerol, and an acetic acid and water activator solution to create a bioplastic. The study will examine these bioplastics’ chemical composition, crystalline structure, mechanical properties, and reactions to UV radiation and microbial development. Researchers and developers are interested in sago starch, a staple meal in Palopo City, South Sulawesi Province, Indonesia, as a sustainable material. Sago starch is advantageous due to its renewable nature and eco-friendly properties. XRD, mechanical characteristics, and microbiological development in sago bioplastic are examined in the study, providing valuable insights. Tawaro sago bioplastic has no heavy metals, according to XRD. The mechanical characteristics have improved significantly, reaching 2,867 N/mm 2 . A 48-hour UV radiation exposure within limitations changed the chemical chain, causing the improvement. Furthermore, bacteria grow swiftly on sago bioplastic. This research promotes sago-based bioplastics as an eco-friendly alternative to traditional plastics, promoting environmental sustainability. This research supports the global drive to create eco-friendly materials. Using Tawaro sago starch, creative solutions for a greener, more sustainable future are possible, with bioplastics offering a compelling alternative to existing plastics and lowering their environmental impact.

Peculiarities of phase and structural transformations during the carbon-thermal recovery of high-speed steel slag with the production of an alloying additive were investigated.This is necessary to determine the technological indicators that allow reducing the loss of high-value elements during the production and use of the alloying additive.A gradual change in the degree of scale reduction from 32 % to 69 % and 77 % led to an increase in the appearance of the solid solution of alloying elements and carbon in the α-Fe lattice with respect to FeWO 4 and Fe 3 O 4 .Along with this, Fe 3 C, FeW 3 C, WC, VC, V 2 C, and Cr 3 C 2 were manifested.At the same time, the formation of polyhedral and rounded particles of different chemical composition and the formation of a spongy microstructure was observed.It was determined that the most ac- The problem of increasing the efficiency of 13ХFА pipe steel for oil and gas wells by using selective selection of charges for smelting them in an electric arc furnace is considered.4 batches of different chemical heterogeneity were studied.It was found that melt 1 from a purer charge 1 contains a smaller amount of harmful impurities in the form of surface-active substances (surfactants), which affect grain growth when samples are heated for quenching.Thus, melts 1 and 2, containing a smaller amount of surfactants in the charge, have a greater tendency to austenite grain growth and lower hardenability ceptable degree of recovery is 77 %.At the same time, the degree of reduction of 69 % is also sufficient since due to the residual carbon in the form of carbides, an increased reduction capacity is ensured with additional reduction of the oxide component in the liquid metal during alloying.The spongy microstructure provides relatively fast dissolution compared to standard ferroalloys, which causes a reduction in the total melting time while reducing the resources spent.No phases and compounds characterized by an increased tendency to sublimation were detected in the obtained alloying additive.That is, there is no need to provide additional conditions that prevent the loss of high-value elements during evaporation with the gas phase, which causes an increase in the degree of extraction of alloying elements.The indicators of the obtained alloying additive make it possible to melt alloyed steel in an electric arc furnace with respect to brands whose composition does not have strict restrictions on carbon, while replacing a part of standard ferroalloys.
Keywords: carbon thermal recovery, slag of high-speed steels, oxide man-made waste, structural-phase transformations.

Yevhen Buturlia
Admiral Makarov National University of Shipbuilding, Mykolaiv, Ukraine ORCID: https://orcid.org/0000-0003-2604-5664 compared to melts 3 and 4, the charge of which is relatively heavily contaminated with surfactants.This is due to the low relatively free energy of melts 3 and 4. The study showed that at a relatively low tempering temperature (300 °С) there was an insignificant change in the mechanical properties of the samples (R m , KC, etc.).Hydrogenation of steels significantly reduces the strength of steels from all melts, however, an increase in tempering time leads to an increase in long-term strength.In this case, the maximum impact strength (KC) of all melts is observed after normalization, but samples from melt 1 have a higher IC.When the samples were held (570 °С), the nearboundary layers of steel grains were enriched with P, Sb, Sn, As, leading to embrittlement and weakening of intergrain cohesion and a decrease in the energy of boundaries.In the process of testing at -80 °С, cracks along the grain boundaries are visible on the fractures of the samples after brittle tempering.By increasing the purity of metal waste for smelting pipe steel, it is possible to improve the complex of its properties, and hence the durability of seamless pipes for the oil and gas industry produced from it.
Keywords: selection of metal waste, pipe steel, heat treatment, temper brittleness, cold resistance, oil and gas industry.

Ivan Lahodzinskyi
National Technical University of Ukraine "Igor Sikorsky Kyiv Polytechnic Institute", Kyiv, Ukraine ORCID: https://orcid.org/0000-0002-7986-9440 The object of research is the processes of the formation of brazed joints and the stressed state.The subject of research is structure, chemical composition, long-term high-temperature strength at a temperature of 900 °C, speed of high-temperature salt corrosion.Existing brazing filler metals have a high-temperature performance of 40-50 % of the performance of the SM93-VI and SM96-VI alloys.Despite this, brazing is the main technique of joining modern heat-resistant cast alloys.Therefore, the development of new brazing filler metals that ensure the formation of joints with increased long-term high-temperature strength is relevant.Ship gas turbine blades operate at a temperature of 900 °C.The purpose of the development of the new SBM-4 brazing filler metal is to achieve long-term high-temperature strength of brazed joints at a temperature of 900 °C at the level of 85-90 % of the strength of heat-resistant alloys SM93-VI and SM96-VI.
A two-stage method was used in the development of SBM-4 brazing filler metal.At the first stage, the chemical composition of the brazing filler metal base was determined, taking into account the peculiarities of operating conditions of the blades of marine gas turbine engines and the achievements of materials science of heat-resistant alloys.At the second stage, the depressant and its necessary content were selected.Computer software was used to determine the distribution between the γ-and γ'-phases, taking into account the participation of each element in both dispersion and solid-solution strengthening.Rational limits of concentrations of alloying elements were determined.The criterion was the minimum susceptibility of brazing filler metal to the formation of brittle phases, taking into account the influence of chromium, rhenium, and tantalum concentrations on resistance to high-temperature salt corrosion and high-temperature performance.The long-term strength of SM93-VI and CM96-VI alloys brazed with SBM-4 brazing filler metal is 89-91 % of the strength of the base metal.Technologies of brazing and correction of casting defects have been introduced into production.
Keywords: brazed joints, stressed state, high-temperature salt corrosion, long-term strength.reached values of 1250 MPa and more, while the impact toughness was at the level of 48-50 J•cm -2 .
Modeling the welding process has made it possible to ensure the reproducibility of the characteristics of the welded joint at a level close to that of the base metal, to increase the quality indicators of welded joints, and to reduce the time required to test the technology.The studies of simulator samples showed compliance of the quality of welded joints with the predefined parameters.

Olena Karpovych
Oles Honchar Dnipro National University, Dnipro, Ukraine ORCID: https://orcid.org/0000-0002-0677-5822 It is usually quite difficult to carry out deep penetration of thickwalled products from titanium alloys using conventional welding technologies.In this study, it was proposed to use electron beam welding under high vacuum conditions for the realization of 40 mm thick melting of VT23, VT3-1 alloys.
This paper considers the possibility of obtaining high-quality welded joints from high-strength titanium alloys having (a+β) twophase structures.For the implementation of research works, samples were made from selected materials, samples were welded according to the specified modes, metallographic analysis was performed, and the level of mechanical properties was determined.The research results were verified under laboratory conditions.
The technological features of the processes of electron-beam welding of products with a thickness of 40 mm were considered; the parameters affecting the weldability of titanium alloys and their structure were determined.The welded samples were checked by X-ray non-destructive testing, the microstructure of the welds was studied, and the physical and mechanical properties of the welded joints were checked.It was established that a feature of titanium alloys VT3-1, VT23 is the need for heat treatment after welding under the base metal regimes to improve the characteristics of the welded joint.The resulting strength limit of the alloys after heat treatment movement v eb was varied from 7 to 15 mm•s -1 .The temperature of the experimental welded samples T 0 was varied from 300 K to 673 K. Ti-TiB alloy (a microcomposite alloy with reinforcing TiB fibers) was welded with Ti-TiB alloys, T110, and with niobium.One of the tasks of welding this alloy was to preserve and optimize the structure of this type in the weld.Grinding of boride fibers, loss of their initial orientation, and formation of a dendritic or cellular microstructure was observed in the weld.
Using the methods of raster electron microscopy and micro-X-ray spectral analysis, the microstructure of the weld material was investigated and the dimensional characteristics of TiB fibers under different welding conditions were determined.The analysis of changes in the microstructure of the weld material, the average length ᶏ and the thickness ȩ of the boride fibers in the material of the joints made at different velocities of electron beam movement and initial temperatures T 0 was carried out.It was established that the growth of the ratio ȩ/ᶏ from 0.04-0.07 to 0.1-0.27 is accompanied by significant changes in the microstructure and the mechanism of formation of eutectic phases.
It is shown that the process that determines the formation of the microstructure of the weld material was the eutectic breakdown with the determining influence of the temperature gradient, crystallization rate, supercooling, concentration inhomogeneities, and alloying impurities.
This paper reports a study whose object was material of the weld.The nature of changes in the microstructure of the weld material, which are caused by changes in the supplied energy, alloying elements and heat removal from the melt area, was investigated.Welding was performed with an electron beam at U acc =60 kV, I eb =90 mA, with an elliptical sweep of 3×4 mm.The speed of electron beam in mechanical properties to be corrected, surface roughness was treated.The aim of this study was to optimize the welding parameters of DRSW with surface roughness by analysis using the Taguchi and Anova Methods.In this study discusses about investigates the Resistance spot welding parameters on weld geometry, mechanical properties, and SEM EDS on dissimilar materials of mild steel and stainless steel.The material thickness of the mild steel and stainless steel are 1 mm, respectively.The process parameters of the resistance spot welding joint used, example; surface roughness, current, welding time, and electrode force.Quality welding joint test results include weld geometry, mechanical properties, and SEM EDS.Weld geometry testing to determine the weld nugget profile.The mechanical properties test was shear tensile test, while the SEM EDS included macrostruture and microstructure observations.The results showed the highest nugget diameter 6.65 mm highest shear tensile strength 7.66 kN.The most influential parameter is current by 75.08 %, then surface roughness by 12.35 %.The highest tensile strength has fewer defects.Surface roughness treatment before welding is very good to make welding quality joints between mild steel and quality stainless steel increase.Surface roughness treatment was very good to be included when making welding procedures for welding engineers for welding processes resistance spot welding dissimilar mild steel with stainless steel.
Keywords: resistance spot welding, dissimilar material, mild steel, stainless steel, surface roughness treatment.5/12 ( 125 ) 2023 Pipeline systems play a pivotal role across various industries, serving as the lifelines for transporting materials like oil, water, and gas.Among the welding techniques, orbital pipe welding, particularly Gas Tungsten Arc Welding (GTAW) without filler metal, is the fitting method for joining these critical piping systems.This study examined orbital pipe welding on SS316L pipes with a 114-mm outer diameter and 3-mm thickness.The main goal was to evaluate the weld's tensile strength and microhardness carefully.Constant current and three welding speeds -1.3, 1.4, and 1.5 mm/s -achieved this goal.In addition, welding experiments covered 0°, 90°, 180°, and 270° pipe positions.First, the necessary tools and test objects were prepared, and then the test materials were welded.The final phase was testing tensile strength and microhardness.This investigation used a 5G-specific prototype orbital pipe welding equipment.The 5G method requires horizontal welding with the vertical pipe axis.The study used ASTM E-8M-compliant standardized test material for precise and repeatable tensile strength measurements.This standardization ensured outcomes reliability.One of the significant findings was that 1.4 mm/s welding at the 270° pipe position with 110 A current produced the maximum tensile strength.This shows that these conditions are best for welding SS316L-type stainless steel pipes with an outside diameter of 114 mm and a thickness of 3 mm.Strangely, microhardness testing showed that horizontal distribution welding quality decreased at 1.4 mm/s.This implies that further experimentation may be needed to fine-tune the welding parameters to optimize the process and achieve superior microhardness values.