SU1036786A1 - Cast iron - Google Patents

Abstract

CAST IRON, containing carbon, silicon, manganese, aluminum, magnesium, chromium, vanadium, zirconium and iron, is distinguished by the fact that, in order to increase the heat resistance, it additionally contains titanium, molybdenum and nickel in the following ratio of components, weight %: 2.8-3.8 Carbon 3.6-4.5 Silicon 0.3-1.0 Manganese 0.1-0.3 Aluminum, 1 Magnesium 0.1-0.8 Chromium 0.1- 0.3 Vanadium Zirconium 0.05-0.2 0.01-0.1 Titanium 0.1-0.35 Molybdenum 0.2-0.5 Nickel Rest Iron (L

Description

with

00 Oi The invention relates to black metturgies, in particular, to cast iron compositions for puffers operating under dynamic load conditions and elevated temperatures, such as chain links of conveyor and pusher terrains, 4 furnaces. The heat-resistant cast iron fl of the following chemical composition is known. wt.%: Uglerod2.4-3.0 Silicon5.0-7.0 Manganese 0.3-0.6 Aluminum5.0-7.0 Magnesium 0.07-0.12 Iron Iron Other The disadvantages of this cast iron are low ductility and toughness as well as low liquidity. Thus, with a total content of silicon and aluminum of 10–14%, the elongation is 0.5–0.6%, and strength problems are 180–190 MPa, while the fluidity decreases to 650 mm. The closest to the proposed technical essence and achievable result is heat-resistant cast iron C2 of the following chemical, weight,%: Carbon 3-4.0 Silicon 4-5.5 Manganese 0.3-0.6 Aluminum0.1-0.3 Magnesium 0 , 04–0.1 Chromium, 0.2–0.4 Vandium, 0.1–0.3 Zirconium, 0.05–0.2 IronOstal At the specified ratio of elements of chemical composition, the interaction of vanadium, chromium and aluminum with sulfur, oxygen, hydrogen, nitrogen and phosphorus. When this is formed, nonmetallic inclusions (sulfides, oxides, hydrates and nitrides) are deposited on the grain boundaries, which significantly reduces the concentration of these elements in the solid solution on the α phase (matrix). When the alloy is heated to high temperatures (700-900 s), the oxidation process proceeds, as a result of which continuous diffusion of chromium, vanadium and aluminum from the solid solution to the metal-oxide film interface occurs. The consequence of this is the depletion of the solid solution of these chemical elements, which significantly reduces the long-term strength at high temperatures. Thus, the tensile strength at a temperature of 800 - 850 ° C is 90 - 100 MPa. This circumstance does not allow the use of known cast iron for the manufacture of parts operating under dynamic loads and elevated temperatures, such as chain links of conveyor and push thermal circuits. The aim of the invention is to increase heat resistance. The goal is achieved by the fact that cast iron containing carbon, silicon, manganese, aluminum, magnesium, chromium, vanadium, zirconium and iron additionally contains titanium, molybdenum and nickel, with the following component ratios, wt%: Carbon 2.8-3 , 8 Silicon3.6-4.5 Manganese0.3g1.0 Aluminum0.1-0.3 Magnesium0.04-0.1 Chrome0.1-0.8 Vanadium 0.1-0.3 Zirconium0.05-0.2 Titanium0 , 01-0.1 Molybdenum0.1-0.35 Nickel0.2-0.5 Iron, Else Introduction to the alloy of titanium, as a more active element than chromium and vanadium, by combining with oxygen, sulfur, hydrogen and nitrogen, contributes increase the content Roma and vanadium in solid solution. At high temperatures, oxide films of complex composition are formed on the surface of the alloy, which prevent the diffusion of oxygen to the surface of the metal and, thereby, reduce the scaling process. At the same time, the diffusion of the alloying elements from the solid solution to the Meranif interface reduces the oxide bar, which contributes to an increase in the alloy's long-term strength. In addition, titanium crushes graphite inclusions and ensures a more uniform distribution of these inclusions in the matrix volume. The presence of nickel in the indicated ratios with vanadium and chromium makes it possible to obtain a solid solution with the / phase with a relatively small amount of fine carbides of complex composition located inside eutectic grains, which, during prolonged exposure (1.5-2.0 hours) in the range temperatures of 650 are dissolved in the matrix and further doped. When the content of titanium is more than 0.1% in the solid solution, titanium carbides insoluble at high temperatures are formed, which, located at the grain boundaries, reduce the strength of the alloy both in the cold and in the hot state. At less than 0.01% of the titanium content, a part of chromium, vanadium and molybdenum is combined with oxygen and other non-metallic inclusions, as a result of which the content of alloying components in the matrix decreases.

An increase in the molybdenum alloy of more than 0.35% leads to the formation of carbides and the depletion of the matrix by molybdenum. The content of molybdenum in the alloy below 0.1% does not have a significant effect on the strength at high temperatures.

The optimum ratio of nickel and molybdenum in iron is 1.0: 0.75 and 1.5: 1.0, while chromium and titanium1.5: 1.0 and 2.0: 1.0.

The amount of carbon, manganese and magnesium was selected on the basis of the experience of producing high-strength cast iron.

The iron is melted in a 300 kg induction furnace. As the charge materials use refined cast iron

aluminum and steel waste). Ferrochrome, ferrovanadium, ferronickel, ferromolybdenum and ferrotitanium are introduced into the ladle when cast iron is poured. Silikonium with horse will modify the cast iron directly in the mold after spheroidizing the treatment of cast iron in the ladle with magnesium ligature LCM-b.

Mechanical tests were carried out at 20 ° C on an IMASH-30 tensile testing machine and on a PTMV-30 universal tensile testing machine. The test times are 50 hours and 100 hours. The fluidity is determined in a Keri spiral at.

The chemical composition and properties of the proposed iron are presented in table. 1 and 2.

b l and c (3 1

.T a

The test results (Table 2) indicate that the long-term strength of cast iron doped additionally with titanium, molybdenum and nickel, at a temperature of 50 and 100 hours, increased 1.5 - 1.7 times while maintaining fluidity and scaling resistance. high level.

Cast iron of the specified chemical composition is recommended for the production of castings.

Table 2

working under conditions of increased dynamic loads and temperatures. The economic effect from the use of cast iron due to the replacement of heat-resistant and heat-resistant steels 20X25N20C2L and H25N20C2L from which chain links were made, as well as flasks, will amount to 0.37 thousand rubles, a ton of suitable cast, and based on the volume of use of these parts in the plant - 23,5-25,0 thousand rubles.

51036786

The expected economic effect of the tractor and agricultural from the maximum use of pre-mechanical engineering will be 187 lagging inventions in the industry 190.0 thousand rubles.

Claims (1)

PIG IRON containing carbon, silicon, manganese, aluminum, magnesium, chromium, vanadium, zirconium and iron, characterized in that, in order to increase the heat resistance, it additionally contains titanium, molybdenum and nickel in the following ratio of components, weight. %: Carbon 2.8-3.8 Silicon 3.6-4.5 Manganese 0.3-1.0 Aluminum 0.1-0.3 Magnesium 0; 04-0.1 Chromium 0.1-0.8 Vanadium 0.1-0.3 Zirconium' 0.05-0.2 Titanium 0.01-0.1 Molybdenum 0.1-0.35 Nickel 0.2-0.5 S Iron Rest ω a with about? m 00 00