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DOI: http://dx.doi.org/10.20534/ESR-16-9.10-45-47
Saydakhmedov Ravshan Khalkhadjaevich, Professor, the Faculty of Mechanics and Machine building E-mail: ravshansaid@mail.ru Bakhadirov Kudratkhon Gayratovich, Tashkent State Technical University, Senior scientific researcher, the Faculty of Mechanics and Machine building E-mail: bahadirov@gmail.com Rasulov Alisher Khakimovich, Tashkent State Technical University, Senior scientific researcher, the Faculty of Mechanics and Machine building E-mail: kudratg@mail.ru Rosulov Ro'zimurad Khasanovich, Tashkent Institute of Textile and Light Industry, Associate professor, the Faculty of Mechanics and Cotton Ginning
E-mail: rasulov.ruzimurad@mail.ru
Investigation of technological parameters of the asymmetric rolling and the physical and mechanical properties of materials
Abstract: In the article the results of experimental studies to determine the technical parameters of the asymmetric rolling and physic-mechanical properties of materials. To determine the mechanical properties of materials selected hardness. The hardness was measured on strip hardness tester series KV 250 are designed for the hardness testing method: Brinell, Vickers and Rockwell.
Keywords: rolling metal, sheet metal, copper strips, hardness, material properties, microstructure, tensile strength, tearing, stretching and annealing.
Introduction. In industry, most of the metal is processed by different types of rolling. When sheet metal rolling main objectives are to reduce the thickness of the sheet metal to the desired size, improve the mechanical and other properties.
Many large industries sheet materials are widely used. The high price and limited characteristics forming the processing of pressure are considered major disadvantages of sheet materials, which limit its wider application in various industries.
Rolling of the strip (sheet material) can be symmetric (conventional) or asymmetric. When the parameters of the upper and lower rollers, a linear velocity and the radii of the friction coefficients of the upper and lower surfaces are rollers is symmetric rolling. If one or more parameters of the upper or lower cylinder has a difference, it has an asymmetric rolling.
Objects and methods of investigation of hardness was determined to strip hardness tester series KV 250 are designed for the hardness testing method:
— Brinell (DIN EN ISO 6506 1/1-1/2.5-1/5-1/10-1/302.5/6.25-2.5/15.625-2.5/31.25-2.5/62.5-2.5/187.5-5/255/62.5-5/125-5/250)
— Vickers (DIN EN ISO 6507 1 -2-3-5-10-20-30-40-5060-80-100-120)
— Rockwell (DIN EN ISO 6508)
— Hardness of the spherical insertion on plastic (DIN ISO 2039 T1)
All procedures meet the requirements of international standards DIN, DIN-EN, ASTM, ISO, etc.
The depth of the wells was determined in the spherical device Ericson punch with a diameter of 20.0 mm with specifications:
— The measuring range, mm (0 to 15.0); — The price of dividing the vertical scale reading device, mm, 1.0; — The price of dividing the dial reading device, mm, 0.05;
— Limits ofpermissible absolute error, mm, 0.05.
Elongation, tensile strength was measured on a universal testing
machine series SUN/5 with the specifications:
— Nominal capacity, kN, 50; — Speed range, mm/min (0,001-200); — The maximum distance between the gripping fasteners, mm 1000; — Permit movements mm, 0.001;
— Positioning accuracy, mm, 0.02; — Error in the measurement of the load,%, ± 0,5.
The microstructure was determined by an industrial microscope Nikon ECLIPSE L150, consisting of the following main components: visual tubes, lenses, illuminator L-UEPI, turning the lens, lens kit (x5, x10, x20, x50, x100), the object holder, microscope base, lamp holder, polarizer, analyzer table.
Test Methods. Tensile tests were performed on samples to GOST 1497.
Tests on the hood of a spherical hole were performed according to GOST 10510 with a punch radius of10 mm.
Determination of the grain size was carried out according to GOST 21073.1.
Laboratory tests were carried out on samples of the rolled copper strip method by asymmetric condensed upstream of the (solid state) and after annealing (soft state) on the intermediate sizes 3.0 mm and 0.5 mm.
The samples were subject to the following types of studies:
— Determination of elongation, tensile strength;
— The depth of the extrusion Ericson;
— Determination ofthe hardness ofthe rolled and annealed strip;
— Metallographic: Macro and Micro studies.
For testing samples numbered according to Table 1.
Results and their analysis. Identification of technological parameters of the asymmetric rolling and the physical and mechanical properties of materials before and after annealing.
Section 5. Materials Science
Table 1. - Marking specimens
Strip thickness, mm Status bar Type of test Marking sample
3.0 Hard Hardness 1-3
Soft Elongation, tensile strength 4-7
Macro and Micro studies 8
0.5 Hard Hardness 9-11
Soft Depth extrusion Erichsen 12-14
Macro and Micro studies 15
The hardness tests were determined prior to annealing. Anneal- the bell furnaces f. «EBNER». Modes annealing roll bars are pre-ing rolled coiled strip was carried out in a hydrogen atmosphere in sented in Table 2.
Table 2. - Annealing roll band
The thickness of the rolled metal, mm The heating temperature, 0 C Time, hour
heating exposure cooling
3.0 480 6 4 5
0.5 450 6 4 4
Elongation and tensile strength were determined for the strip Ericson extrusion depth determined for strip 0.5 mm thick. The
thickness 3.0 mm in the soft state (after annealing). mechanical properties of the strip are shown in Table 4.
The mechanical properties of annealed strip of 3 mm thickness are shown in Table 3.
Table 3. - The mechanical properties of the annealed 3.0 mm strip thickness
Number of the sample Mechanical properties
a. „/mm 2 in N 0 0 10%
4 226 48
5 221 48
6 213 54
7 215 56
Table 4. - Depth Ericson extrusion (punch diameter 10 mm) for 0.5 mm thick strip
Number of the sample The depth of the extrusion, mm
12 8.8
13 9.1
14 8.9
The macrostructure of the cast strip in the transverse direction shown in Fig. 1.
Figure 1. — The macrostructure of the cast strip (x100)
The microstructure shown in Figure 2 sample studied corresponds № 8 recrystallized state copper after deformation and annealing. The microstructure of the cross-sectional areas of fibrous and no residues cast structure — this is due to a high degree of deformation
Visual inspection of the cast strip surface and the presence of internal defects were detected. In figure 2, and figure 3 the microstructure of the rolled and annealed copper strip is shown.
Figure 2. — microstructure rolled to 3.0 mm and annealed strip (x100)
by rolling the copper strip annealing and moderate temperatures. The structure consists of equiaxed grains with an average copper grain size of 35-40 microns.
Figure 3. - microstructure rolled to 0.5 mm and annealed strip (x100)
The microstructure shown in Fig. 4.3 sample studied corre- of no fibrillation. The structure consists of equiaxed grains with an sponds № 15 recrystallized state copper after deep deformation and average copper grain size of 15-20 microns. annealing temperate. The microstructure of the cross-sectional areas
References:
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3. «Technological parameters of the pressing process.» Methodical instructions for practical classes. SFU Institute of Nonferrous Metals and Gold; Krasnoyarsk, - 2007.
