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Section 4. Materials Science
Norkhudjaev Fayzulla Ramazanovich, Department of Materials Science, Tashkent State Technical University, Tashkent, Uzbekistan Aliqulov Adham Xoltoji o'gli, Magistrate of department Foundry manufacture, Tashkent State Technical University, Tashkent, Uzbekistan E-mail: norxojaev.fayzulla.65@mail.ru
DEVELOPMENT OF TECHNOLOGY FOR METAL LAYERED COMPOSITIONS WITH CASTING METHOD ON GASIFIED MODELS
Abstract: The paper is development of technology for metal layered compositions with casting method on gasified models.
Keywords: Metal layered compositions, casting method on gasified models, ametalworking tools, dies - matrices, steels, carbide and molybdenum, and their alloys.
1. Introduction
Scientific research on development of metal layered compositions are being carried out in more than 30 countries of the world. A ten-fold increase in the speed of processing metal-working on machinetools (3500-50000 rev/m), increase the impact of the internal stresses in the machining of components leads to higher quality requirements of the tool - tools and parts, in the whole improvement of production. This intern requires the high performance properties from the materials of details. As static information demonstrates that, every year in the world for the development of high-quality materials spent US$ 5-6 billion, including Europe and the CIS countries is the number of 1-2 billion US dollars, and in the production in the highly countries 4-5 billion spent in US dollars. Currently, under the conditions of production intensification when manufacturing the quality products the development of metal and non-metal
compositions with high mechanical properties is one of the important production tasks.
In the years of independence our country focuses on producing high-quality and competitive engineering products in the global market. The development of the engineering industry, its products, which must meet modern requirements to increase the reliability, safety and life of the manufactured machinery, apparatus and equipment and materials, improving their quality have led to significant results.
Nowadays, it is important to increase the economic efficiency of industries, on the development of a new composition of the materials produced, as well as the efficient and cost-effective improvement of technologies for the production of products by casting in order to enhance the performance of economic: in this aspect the purposeful scientific -research work is the very improvement, as well as the carryinj out of scientific-research in the direction
of the development of composite materials using special metal layered compositions ensures product quality; development of technology for metal layered compositions; improvement of theoretical and technological bases of thermal treatment enhancing the strength of the metal layered compositions; creation and production of new energy and material saving metal layered compositions based on the latest scientific and technological achievements, which economize scarce tool materials and increase productivity. The above-mentioned research areas, and the results of research carried out in these areas are the justification of the relevance of the topic of this thesis.
2. Statement of A Problem Analysis of the current and prospective estimation of the possibilities of offered technology application have allowed to choose as objects:
- ametalworking tools (machine-building direction), the most representative and widely used rigid tools: round die type M18h2 and M42; side-and-face milling cutters; grooved stamps; matrices for various purposes [1].
The main goal of metal layered compositions development is to reduce the consumption of scarce alloyed steels, labor, creating a high level of compressive stress in the operating member of metal layered compositions both at the manufacture and at thermal treatment.
Taking into consideration the selected method for obtaining the metal layered compositions the casting on gasified models, as well as the fact that the basis for metal layered compositions should serve the cast metal alloys, as a tool component metal materials are taken.
It should be noted that the above group of materials performs the main role in tool production. It includes tool steels and hard alloys. The paper presents the chemical composition of the used tool steels, carbide and molybdenum, and their alloys.
For the manufacture of metal layered compositions it is necessary to perform the following basic technological methods: preparing offoam polystyrene for the production of foam model; manufacturing of tool's foam model; preparation ofthe working element; preparing and obtaining ofcasting; getting tool [1-3].
Figure 1. Metal layered compositions "9HC steel-Obtaining of metal layered compositions of a type cast structural steel - work paste is possible in the case of the comparability of physical and mechanical properties of materials. The compositions
cast structural steel 40HL" - cast circular dies of this type are a connection between the tool and cast structural steel. The main advantage of this class of compounds is the reducing of the consumption of alloy tool steels, due to the partial replacement
of their more affordable structural steel and reducing the complexity of manufacturing punching and multiedge cutter of a complex profile [1; 3].
The composition cold work tool steel - cast structural steel was selected for the manufacture of circular dies-matrices (Figure 1).
Analysis of the ratio of the geometric parameters of the working elements and the tool bodies allowed to establish that for this class of instrument the paste thickness in the contact area with the melt should be 2-5 mm.
3. The Concept of the Problem Decision
Microstructural studies were conducted on the use of metal layered compositions with hard working element made of the cold work tool steel. The study of the metal layered composition steel 9HC-steel 40HL the round dies M18 x 2 and M42 have been tried to manufacture. The various flux (Na2B2O7 and others) were used in the compositions as an intermediate layer.
As previously was indicated, for the manufacture of complex multiedge cutter the compositions of hot-work, high-speed steels - cast structural steel were used. The specificity of the operation of a given class of tool is due to the high requirements to the tool body, operating under the dynamic and cyclic loads (steel 40HL, 40HGL, 40HGFIL). As hot-work tool steels the steels: R6M5, 10R6M5-MP, R6M5K5 and others were selected [1; 3].
Variant with an intermediate layer is practically the unique for compositions, the components of which have very different physical characteristics. These compositions are solid alloys - steel, molybdenum alloys - steel. For punching tools (matrices for hot metal pressing) and drilling tools (drill bits, chisels, and milling cutters) the pastes made of hard alloys intended for brazed tool were used. To create compositions as a material of the intermediate layer the alloys of Cu-Ni-Mn system, Cu-Ni with a thickness of 0.2-0.6 mm, sprayed by the plasma-method, were used [1; 3].
As indicated above, for the tools body casting structural steel was used, and as its main working
part molybdenum and its alloys (MCH VM and Mo-TiC), as well as the hard alloys of VC and TC group.
The mechanism of the formation, composition, structure, physical and mechanical properties of metal layered compositions of a type "cold work steel - structural steel", "hot-work steel - structural steel," "hard metal - structural steel" and "molybdenum and its alloys - structural steel" were fully studied (Figure 2) [1; 3].
Study of metal layered compositions of a type "tool material-structural steel" confirmed the obtaining of continuous compounds.
The proposed version of the MLC production technology with low-melting working element was intended mainly for the manufacturing of tillage tools of different types. In this case the powder hard alloys in the binder are applied in the form of a paste or are placed in the form of premanufactured pastes in a cavity specially prepared. The melting temperature at the time of pouring 1650-1700°C. The use of boron compounds for the manufacture of various composite materials having a high level of mechanical, thermal, electrical and other properties, gets quite widespread, above all, by the use ofboron compounds themselves [1; 3].
As a result, consideration of the mechanism and characteristics of the formation of all types of connections allowed to predict the course of the process and select the technological conditions for the creation of this sort compositions.
The results of macro- and microstructural studies of the compositions showed that the discontinuity in the transition zone is not detected. Indicators of microprobe analyzes of the compositions have high depths of mutual penetration of elements Cr, Ni, W up to 300 microns and deep. Distribution of micro-hardness over the cross section of the compositions showed that the highest hardness (1100-1400 HV) has a carbide sub-zone, then the curve monotonically decreases in hardness of the eutectic and hypoeutectic subzones and reaches a minimum in the area of the sinter skin and carburizing, 250 ... 350 HV [1; 3].
a) b)
Figure 2. Microstructure of transition zone of metal layered compositions: " sintered alloy
of Mo-TiC-PR N58F - cast structural steel 40HNML" (a), a layered metal composition "sintered alloy Mo-TiC-Ni - cast structural steel 40HNML" (b). X150 1 - area of migration; 2, a zone on the base of transition layer material; 3 - sinter skin; 4 - carburizing zone
Taking into account and summarizing the results of the research of all types of compositions, one can imagine the mechanism and features of connections formation between the elements of the composition with the participation of the intermediate layer.
There has been determined the mechanism and installed the features of forming a connection between elements of metal layered compositions, in which the contact of the melt of structural steel with the paste surface - working, cutting element crystallizes to form a solid sinter skin followed by melting the material of the intermediate layer and the interaction of the resulting melt with limiting it solid surfaces: on the one side of the tool material, on the other - of steel. The result is a transition zone of composition having a complex structure and phase composition comprising the interaction products between the elements of the melt and the basic constituents of the composition. Based on these studies there
has been developed a production technology for a number of metal layered compositions for metal-cutting and tillage tools. Analysis of the mechanism and characteristics of the formation of all obtained types of compounds of metal layered compositions allows to predict the course of the process and select the process conditions for the creation the layered metal compositions with desired properties.
5. Conclusions
There have been worked out the bases of working elements preparing from the tooling materials, necessary and sufficient for the forming of a reliable and efficient composition. These technological basics play an important role in the obtainining of metal layered compositions.
On the basis of a carried out research there have been developed the original technologies of obtaining of some metal layered compositions of the end use for metal working, soil cultivating and drilling tools.
References:
1. Norknudznaev F.R., Nazarov A. M., Yakubov L.E. Sintered powder composition on the basis of Mo
- TiC. India. International Journal of Advanced Research in Science, Engineering and technology, -2016. - Vol. 3. - Issue 7. July. - P. 2347-2350. (05.00.00 №8).
2. Norknudznaev F.R., Yakubov L.E. Actual prospects of application of type "Fss - an intermediate alloy
- solid working element" in manufacture of drill tools. Austria. European Sciences review Scientific journal, - 2016. - № 7 - 8 (July - August). - P. 176-178. (05.00.00 №3).
3. Norknudznaev F. R. The current state of the problem of creating metallic layered compositions // III International Scientific and Practical Conference: "Modern Materials, Machinery and Technologies in Mechanical Engineering" Collection of scientific articles. 19-21 April. - 2016 - Andijan. - P. 270-275.
