CC BY
23
Sectiion 7. Materials Science
DOI: http://dx.doi.org/10.20534/ESR-17-1.2-40-42
Rasulov Alisher Khakimovich, Tashkent State Technical University, Senior Lecturer of the Department "Materials Science ", the Faculty of Engineering technology E-mail: kudratg@mail.ru Abdulaziz Yusupov Abdullazhanovich, Tashkent State Technical University, Assistant of the Department "Metal Forming", the Faculty of Mechanics and Machine building E-mail: yusupov_mmf_mmib@umail.uz Bakhadirov Kudratkhon Gayratovich, Tashkent State Technical University, Senior Lecturer of the Department "Materials Science ", the Faculty of Engineering technology E-mail: bahadirov@gmail.com Koraboeva Maksuda Saidovna, Tashkent State Technical University, Undergraduate of the Department "Metal Forming", the Faculty of Engineering technology
Manufacturing technology carbide roller inlet box crate № 25 using refractory metal powders
Abstract: The article presents the results of a study of the obtained sintered molybdenum alloy, comprising: 60-62% TiC, 20-22% Ni, 4% W, 4% Fe and the balance molybdenum Mo, for the production of roller introductory box stand № 25 and increase their longevity by selecting the optimum combination of strength and ductility. One of the main objectives of this work was the development of composition and technology of sintered powder molybdenum alloy. Beyond the basic components of TiC and Mo present in the composition administered in order to improve process performance and Ni, W, and Fe. The working part of the matrix is also used new sintered powder molybdenum alloy.
Keywords: refractory metal carbide, molybdenum alloy, the composition, the roller matrix, mold, a mixture powder, sintering, molybdenum, titanium, steel composition, heat treatment, strength, ductility.
Create materials based on highly dispersed powders of refractory metals refers to the key issues of the modern economy. At present, the industries the task of getting carbide tools with special mechanical, technological and physical properties on the basis of refractory metal powders.
In addressing the complex to improve performance, reliability and durability of the tool, improving the quality of products is an important development of new materials or improving physical and mechanical properties of existing.
Development and improvement of production processes [1] is inseparably associated with the use of hard alloys, which contributes to a significant increase in operational tool performance and productivity.
One of the promising ways to improve hard alloys is the development of technologies [2], which provides simultaneous improvement in properties such as toughness and wear resistance, strength and ductility compared to standard. It is the combination of these properties provides a tool life.
The desired combination of properties will have an alloy with high polydisperse component. It is expected that the major phase grains provide plasticity, and small grains — increased wear resistance of the alloy. Yield strength and hardness of the compressive strength with the increase of the fine grains in the alloy structure increases. Flexural strength is practically independent of changing the ratio of large and small grains and in a mixture of the alloy and decreases only slightly at the highest content of fine grains. Reserve plastic deformation with the increase of the proportion of fine fraction in the grain mixture of titanium carbide and 40% remains practically unchanged, while increasing to 60% is reduced slightly (10%). Analysis of the data shows that the most advantageous combination of wear resistance and ductility alloys have a ratio of coarse and fine fractions 60:40.
Objects and methods of research. Completed development of the composition of the system Mo-TiC-Ni-W-Fe alloy molybdenum sintered powder for the production of roller mill inlet box № 25. One of the main objectives of this work was the development of
Manufacturing technology carbide roller inlet box crate № 25 using refractory metal powders
composition and technology of the new sintered molybdenum powder composition. Beyond the basic components and TiS Mo in the composition administered to improve the technological and operational characteristics of Ni, Fe, and W:
- molybdenum (Mo) — provides flexibility, heat resistance, corrosion resistance;
- titanium (Ti) — provides the heat resistance, mechanical strength at high temperatures, corrosion resistance, and allows to provide the optimum ratio of strength and ductility;
- nickel (Ni) — was introduced into the composition to achieve the desired workability and plasticity of the powder mixture. Introduction of nickel in the alloy provides good compressibility and by sintering — the required density of the work piece, which positively affects the performance properties. Also Ni — provides toughness, mechanical strength and corrosion resistance (the parts used at high temperatures);
- iron (Fe) — is also introduced into the composition to improve processability due to reduction of oxides on the surface of titanium carbide particles and solid-solution strengthening due to the tool uptake titanium molybdenum;
- tungsten (W) — provides hardness and heat resistance, abrasion resistance, and tungsten is added in the composition for solid solution hardening molybdenum bases and to improve the hardness of the alloy.
Preliminary experiments showed that the eutectic alloys to create by sintering a powder composition comprising the same is not
possible, since the sintered alloy does not meet the requirements on any parameter. Therefore, development of an alloy — replacer was carried out, on the one hand, in the direction of increasing the content of TiC, and on the other hand, in the direction of insertion of additional refractory metal additives improving technological and operational characteristics of the alloy.
Comparative alloy assessment was conducted by two characteristics: bending strength (ab) and Rockwell hardness (HRC). As is known, these characteristics are well correlated with characteristics such as heat resistance and hot hardness determining operability and durability of the tool during hot forming. Therefore, when developing the alloy for the evaluation criterion in determining the optimal composition were taken ab and HRC.
Optimization of the method carried out with the assistance of mathematical experiment planning. The initial starting point of an alloy containing 60% of TiC, 4% of Fe, 20% of Ni, 4% the W and the balance molybdenum Mo, who was quite an acceptable level of monitored property values (ffb = 900 MPa, HRC = 80) was selected in the design.
Using the method of steep ascent in the optimization of the formulation it was determined by the composition of the powder composition, which has been adopted as the basis for further research, and provides a level of strength ab = 1150MPa and HRC = 84 (Table. 1). Optimum composition of a powder composition comprising: 60-65% TiC, 20-22% Ni, 3,5% W, 3,5% Fe, and the balance molybdenum Mo.
Figure 1. The dependence of the calculated values for bending strength (a) on the content of TiC
Figure 2. The dependence of the calculated values for bending strength (ab) of the Ni content
System Technology for producing sintered molybdenum alloy Mo-TiC-Ni-W-Fe. An important role in achieving a high level of properties plays a technology ofpreparation of the composition and mode of its sintering. Preparation of the powder mixture was carried out in small laboratory ball mills and at a ratio ofvolume to volume mixture of balls with a diameter of 20-40 mm carbide VK6 1: 4. Included in the components of the composition were divided into two groups:
the first included Ni, W and Mo, the second TiC. Both groups were loaded into different components and mill mixed were ethanol in the medium for 10-12 hours. Further, the compositions were combined, and the final mixing lasted more 6-8 hours. The mixture was then placed in a distiller and the temperature was maintained at 100-120° C for 8-12 hours. The dried mixture was kneaded on 8% plasticizer rubber solution in gasoline, then held in an oven at drying temperature
100-120°C for 20-30 minutes. The finished mixture is compressed to form a pressure of 100 kgs/ mm2 in the press — the unit P4626. After pressing, the product is dried in a steam oven at 100-120°C temperature for 18-24 hours, and then subjected to preliminary sintering in a hydrogen atmosphere at a temperature 1000-1100°C delayed 1 hour. final sintering mode is selected depending on the purpose of the product. So, for forming tools operating at high temperatures and pressures, sintering is carried out under the regime: Wednesday - the vacuum is not lower than 3.10 mm. Hg. Article; sintering temperature 1450-1500°C delayed 1-0,5 hours; sintering time of 2-3 hours.
For the manufacture of molybdenum powder samples tests were conducted on the hardness, flexural strength and determination of their specific weights and densities. Test results showed that Table 1. - Plan to optimize the composition
the hardness of the test samples averaged 83-84 HRC; density p in the range 5.5-6.0 g/cm3 and a flexural strength within ub 105-115 kgs/m2 (Table 1).
Test results showed that the hardness of the test samples averaged 84 HRC; specific gravity p 5.5-6.0 g/cm3 and a flexural strength within ub 1150 MPa. Optimum composition of a powder composition comprising: 60-62% TiC, 20-22% Ni, 4% W, 4% Fe, and the balance molybdenum Mo.
Samples of molybdenum carbide tools are made in the amount of 2 pieces each under the Innovation Project OTH-economic agreements 07/08/2015 and 12/04/2013 from 41/10 and 25/10 from the city of 12.04.2012 with JSC "UzKTZhM" and tested HNVFs in number 2 ofJSC "Uzmetkombinat". of the new sintered alloy by a steep ascent
^^^^^Factors № experience TiC,% Ni,% W% Fe, % cb kgs/mm2
Х1 Х2 Х3 Х4 Y
1 Bi +2 -
2 Bi. +5 - - - -
3 Шаг 1 - - -
4 № 1 56 22 3,5 3,5 -
5 № 2 57 22 3,5 3,5 -
6 № 3 58 22 3,5 3,5 110
7 № 4 59 22 3,5 3,5 -
8 № 5 60 22 3,5 3,5 -
9 № 6 61 22 3,5 3,5 -
10 № 7 62 22 3,5 3,5 112
11 № 8 63 22 3,5 3,5 -
12 № 9 64 22 3,5 3,5 -
13 № 10 65 22 3,5 3,5 -
14 № 11 66 22 3,5 3,5 106
15 № 12 67 22 3,5 3,5 -
16 № 13 68 22 3,5 3,5 -
17 № 14 69 22 3,5 3,5 -
18 № 15 70 22 3,5 3,5 98
As a result of preliminary testing on the samples from the new ers 6-8 times) and almost the same compared with solid VK6 alloy.
powder sintered alloy of Mo-TiC-Ni-W-Fe tools was greater resis- Also tested molds for pressing powders, shaping tools.
tance compared to standard (steel rollers 8-10 times, graphite roll-
References:
1. Salokhiddin D. Nurmurodov, Alisher K. Rasulov, Nodir D. Turahadjaev, Kudratkhon G. Bakhadirov. "Development of New Structural Materials with Improved Mechanical Properties and High Quality of Structures through New Methods Using New Type of Plasma Chemical Reactor. American Journal of Materials Engineering and Technology - Vol. 3, - No. 3, - 2015, - P. 58-62.
2. Расулов А. Х. Технология изготовления твердосплавного инструмента с оптимальным сочетанием прочности и пластичности. -Ташкент. Таш ГТУ Вестник - Таш ГТУ - 2015. Спец выпуск - 127-133 с.
3. Новак Ф. С. Математические методы планирования экспериментов в металловедении. - Москва, - 1979. - Часть 1, - 96 с.
4. Моргунова Н. Н.и другие. Сплавы молибдена. - Москва: Металлургия, - 1975. - 391 с.
5. Расулов А. Х., Нурмуродов С, Д. Исследование мелкодисперсных порошков тугоплавких металлов.//Химия и химическая технология. -Ташкент, - 2012. - № 3, - С. 55-58.
6. Расулов А. Х. Технология производства ролика вводной каробки клети // Материалы научно-практической конференции //Композиционные материалы. - Ташкент, - 26-27 сентября - 2012. - С. 117-118.
7. Расулов А. Х., Нурмуродов. Создание конструкционных материалов с использованием ультрадисперсных порошков вольфрама. -Ташкент: ТашГТу - 2015. - 172 с.
8. Каламазов Р. У Нанокристаллические структуры и материаловедение. - Ташкент: ТашГТу - 2004. - 98 с.
9. .Alisher K. Rasulov, Kudratkhon G. Bakhadirov, Umarov Erkin Adilovich. Implementation of technology production of composite tools of super-hard materials. European Sciences review. - Vol. - No. 5-6. - 2016. - P. 25-27. - Vienna (Австрия).
10. Нурмуродов С. Д., Расулов А. Х., Умаров Э. А., Зиямухамедова У. А. Создание модельного аппарата позволяющего качественно и количественно предсказывать дисперсность получаемого спеченного порошкового молибденового сплава системы Mo-Tic-Ni-W-Fe. Журнал Вестник гражданских инженеров Санкт-Петербург (Россия) - № 4, - 2016. - 162-166 с.
