Ensuring and coordination of high quality indicators of materials in the foundry industry is necessary in the development of Ukraine's economy. High quality products need to be enshrined in new national standards, harmonized with international and European standards. Thus, the purpose of this work is to analyze national and international standards for quality indicators of vermicular graphite iron and their harmonization with each other. The foundry industry of Ukraine has developed mainly with the use of interstate standards - GOST, which differ significantly from European and international and requires coordination and other approaches to the development of new standards. Today there are a number of international standards: ISO, SAE, CEN, VDG, ASTM, JIS, GB, STAS, which regulate the properties of cast iron with vermicular graphite. Most standards define the range of permissible content of spherical graphite (0… 20%) in the structure of cast iron with vermicular graphite, as well as determine the shape of samples to determine the properties and provide for the determination of graphite on surfaces formed after machining castings. In accordance with the needs of the automotive industry, the Society of Automotive Engineers (SAE) has created the standard SAEJ1887 JUL2002 for cast iron with vermicular graphite. The DSTU standard in force in Ukraine regulates only the temporary resistance to tensile and elongation laid down in the brand designation. Thus, the improvement, provision and harmonization of the national standard at the vermicular graphite iron by achieving high quality indicators of materials in the foundry industry, will ensure the stability of the technological production process, and further entry into international and European markets and a qualitatively new level of domestic engineering. An analysis of the current standards in Ukraine DSTU for cast iron with vermicular graphite is given, as well as its regulated mechanical properties and recommended chemical composition. The properties of similar international and European standards for cast iron with vermicular graphite according to ISO, SAE, CEN, VDG, ASTM, JIS, GB, STAS standardization are analyzed, as well as cross-references to ISO 16112 to other standard brands of the vermicular graphite iron. The conformity of brands of materials, depending on their chemical composition and mechanical properties given in GOST, international and European indicators is found out.
The purpose of this study is to improve the technology of manufacturing spherical disk working bodies of tillage machines to increase their wear resistance and strength. The world's leading manufacturers achieve high wear resistance and strength of discs made of boron-containing steels both in their chemical composition and the choice of rational heat treatment technology. Experimental studies of 30MnB5 steel parts revealed that heating for 15 minutes to a temperature of 850°C and quenching in water was sufficient to achieve maximum hardness values. To prevent hardness reduction and to ensure the necessary elasticity and viscosity of the discs, it is recommended to temper at a temperature of 180°C and combine with heat before painting with powder paint. The application of cutting blanks with cutting of depressions along the outer contour of the disk and internal holes on the laser machine, as well as the formation of the finished shape of parts in the process of hot stamping and subsequent heat treatment in quenching dies. 1. The market of disk working bodies of tillage and sowing machines is studied, technological processes of manufacturing of which it is expedient to improve. 2. Theoretical and experimental study of the structure, structure and material properties of samples of spherical disks of imported agricultural machinery. The choice of 30MnB5 pine steel for their production is substantiated. 3. The improved technological process of manufacturing spherical disks is developed. It is recommended to form them by hot stamping in cold dies and intensive hardening in a water bath. 4. The project development of the section of production of disk working bodies of tillage and sowing equipment is carried out.
The article presents a mathematical model of the heat transfer process when heating metal in a furnace, which describes the thermophysical processes that occur when using industrial technology for heating castings. A simplified model of convective and radiant heating of metal in a furnace, which is based on conventional differential equations, allows to calculate the heating time of the metal. It allows you to evaluate the process of heating the metal in the furnace and find its optimal parameters. The model is widely used and can be applied to study the process of heating the casting of any metal or alloy in the furnace. The adequacy of the model is confirmed by comparing the obtained results of estimating the parameters of the model with experimental data.
The dependence of thermal effects of reactions in the formation of inclusions of vermicular and globular graphite is substantiated in the article. The calculation of thermal effects according to the heat of formation of reagents in cast iron and their dependence on the temperature factor is given. The distribution of temperatures and carbon content in the eutectic shell is shown, increasing the compact inclusion of graphite due to diffusing carbon from the melt through the austenitic shell.
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