Assistant of the Department of transportation systems and technological machines Termez branch of Tashkent State Technical University named after Islam Karimov, Uzbekistan, Termez
Development of the scientific basis for the creation of multicomponent coatings from local raw materials for electrodes for manual arc welding of low-carbon and low-alloy weld steels
На развитие сварочного производства приходится более 50% валовой продукции крупнейших промышленно развитых стран мира. Во всем мире ведутся научные исследования по прогнозированию химического состава сварных швов. В этом направлении возможен выбор сварочных материалов, обеспечивающих эксплуатационные характеристики металла еще на стадии проектирования.
The development of welding production accounts for more than 50% of the gross output of the world's largest industrialized countries. Scientific research is underway around the world to predict the chemical composition of welds. In this direction, it is possible to select welding materials that provide the operational characteristics of the metal at the design stage.
Keywords: energy, metal, electrodes, materials, solid, thermodynamic.
Ключевые слова: энергия, металл, электроды, материалы, твердое тело, термодинамика.
Introduction. In this regard, it is important to improve the quality characteristics of the electrodes on the basis of modernization of the composition of the coating shaft to reduce the cost of the electrode. At the same time, in order to improve the characteristics of the welded joint, it is necessary to develop a methodology that allows optimizing the coating composition of welding electrodes, which determines the chemical composition of the molten metal [1,2].
Extensive research focused on the development of energy and resource-saving welding technologies in the world is carried out by the world's leading research centers and higher education institutions, including: Stanford University (USA), International Institute of Welding (France), Technishe Universitaet Wien (Austria), Polytechnic Institute of Viseu (Portugal), University of Nagoya (Japan), National Technologies Institute of Kumoh (South Korea), N. Moscow State Technical University named after Bauman (Russia), I.M. Extensive research is being conducted by the Gubkin Russian State University of Oil and Gas (Russia), Kiev Polytechnic Institute (Ukraine) and other research institutions .
A number of scientific studies are being conducted around the world to calculate the composition of the weld metal and the thermodynamic and physicochemical properties of welding slag in arc welding with coated electrodes, including: (Stanford University (USA)) , (Scientists of the International Institute of Welding (France) have developed methods to reduce the amount of harmful compounds in the weld metal, such as hydrogen, oxygen, sulfur, phosphorus, in order to achieve the required welding-technological characteristics, (Moscow State Technical University named after N. Bauman (Russia) )) Scientists have determined the degree of dependence of the base metal, slag and metal bath masses due to the characteristics of welding electrodes for low-carbon and low-alloy steels, (Technishe Universitaet Wien (Austria)) arc with coated electrodes Experimental-theoretical methodology for determining the average and partial coefficients of transition of elements in butt welding was developed [4,5].
I.I. from scientists of the CIS countries. Frumin, G.L. Petrov, I.S. Ioffe, I.K. Походня, Э. Votinova, V.V. Podgaetsky conducted and developed research on the development of coating electrodes for arc-welded welding with physical and mechanical properties, given the comparison of the composition of the weld metal and the initial composition. Uzbek scientists M.A. Abralov, R.U. Abduraxmanov, R.M. The Saidovs developed electrodes for spring-arc welding of low-carbon and low-alloy steels.
The cycle of obtaining coated electrodes for arc welding includes a method of selecting the components of the electrode coating shaft on the basis of an improved classification scheme, taking into account their functional application, from their design (formation of high-characteristic weld seam) to production working technology.
Three-way systems of the melting diagram were used, taking into account the substantiation coefficient (Fig. 1) in the selection of the slag base of the electrode coating for spring-arc welding. These three-sided systems have an area where the melting temperature of the slag is 1300 ° C. This temperature satisfies students who are exposed to welding slag when welding steels .
Figure 1. State diagram of three-dimensional systems: a) SaO- Al2O3-MgO, b) Al2O3-SiO2-CaO, c) Al2O3-SiO2-MgO, d) Al2O3-SiO2-K2O, d) Al2O3-SiO2- Na2O, e) SaO- SiO2-TiO2 j) SaO-SiO2-CaF2 z) SaO-SiO2-MgO
The melting point of SiO2-SaO-MgO in the system is 1300 ° C, ie when the content is ~ 50% SiO2, 30% SaO and 20% MgO, SiO2-SaO-A12O3 - ~ 50% SiO2, ~ 30% SaO and ~ 20% A12O3 is limited. SiO2-SaO-A12O3 forms several chemical compounds in the system, along with two or three chemical compounds. These are: CaO · Al2O3 · SiO2, 20% CaO, 37% Al2O3 and 43% SiO2 and soluble at 1550 ° C and 2CaO · Al2O3 · SiO2, 41% CaO, 37% Al2O3 and 22% SiO2 with a melting point of 1590 ° C. (Figure 1). The observed system has a large area of melting temperature of alloys not exceeding 1600 ° C, which ensures the widespread use of slags based on SiO2-SaO-A12O3. The slag in this system is converted to powder on cooling when the SaO content is 48-54% .
In the SiO2-SaO-CaF2 system, which is the basis for the preparation of the main types of electrodes, the melting temperature ranges are much wider and the slag content is close to ~ 50-60% SaO, 15-25% CaF2 and 5-15% SiO2. In the arc zone, CaF2 dissociates to form fluorine ions of fluorspar, thereby reducing the amount of hydrogen and sulfur in the weld metal.
The effect of K2O, Na2O, MgO, A12O3 oxide additives on the SiO2-SaO-CaF2 system is the effect on the density of the slag (Figure 2) and the viscosity of the slag (Figure 3), as well as the separation of the slag (Figure 4) and the coating properties of the slag (Figure 5). researched. Experiments show that when the amount of K2O and Na2O is increased, the viscosity of the slag density and the separation of the slag shell decrease. When the amounts of MgO and A12O3 are increased, the density and viscosity of the slag increase .
Figure 2. The density of slag relative to the type and amount of oxide in the slag in the system SiO2-SaO-CaF2
Figure 3. The viscosity of slag relative to the type and amount of oxide in the SiO2-SaO-CaF2 system is given.
Figure 4. In the SiO2-SaO-CaF2 system, the separation of slag relative to the type and amount of oxide in the slag is given.
Figure 5. The SiO2-SaO-CaF2 system shows the slag coverage relative to the type and amount of oxide in the slag.
Steel St3sp was selected for the preparation of weld specimens. Before welding, the electrodes were rolled at a temperature of 180-200ºC .
Figure 6. Histogram of values of yield strength and strength limit of welds made with electrodes 1-4
Figure 7. Histogram of the value of the relative elongation d of welds made with electrodes 1-4
Based on the results of the research, a technological guideline for the preparation of coatings for electrodes of basic and acidic types was developed.
The reserves of mineral resources of the Republic of Uzbekistan are sufficient, they are the basis of welding materials (marble, dolomite, quartz sand, kaolin, feldspar). As a result, it is possible to improve the technological properties of slag in arc-welded welding of elements in the form of one-component (marble, quartz sand).
Taking into account the basicity coefficient and solubility diagram, the slag-based compositions of base and acid-type welding electrode coatings based on local raw materials were recommended. As a result, the strength characteristics of the welded casting structure can be increased by 10-15%.
The technology of preparation of coatings for welding electrodes of basic and acidic types using materials with low ionization potential has been developed. This technology allows to increase the strength characteristics of the welded casting structure by 12-14%.
- Ermatov Z.D., Dunyashin N.S. Development of electrodes for shielded metal arc welding based of the classification of the coating charge components // Austria. European Sciences review Scientific journal, 2018. - No. 11 - 12 (November - December). - pp. 40 - 41 (05.00.00. №3)
- Dunyashin NS Development of multi-component coating for electrodes for manual arc welding of low-carbon and low-alloy steels. - T .: Fan va texnologiya, 2019 - 160 p.
- Dunyashin NS, Ermatov ZD On the study of the influence of the type of electrode coating on the metal of the weld pool // Problems of mechanics, 2017. - No. 4. - S. 40-42 (05.00.00. No. 6)
- Dunyashin N.S., Ermatov Z.D. On the development of welding electrodes using fused finals // Composite materials, 2017. - No. 4. - С.39-41 (05.00.00. №13)
- Dunyashin NS, Ermatov ZD Improvement of the composition of the charge of electrode coatings based on the determination of the partial transition coefficients of elements in manual arc welding // Bulletin of TSTU, 2017. - No. 4. -S.56-61 (05.00.00. No. 16)