SU1108129A1 - Steel - Google Patents

Abstract

STEEL containing carbon, manganese, silicon, nitrogen, iron, characterized in that, in order to increase wear resistance under friction and abrasive wear at temperatures up to, it additionally contains chromium, nickel, vanadium, titanium in the following ratio of components, wt. %: Carbon 1.40-1.65 17-20 Manganese 0.3 -1.0 Silicon 0.002-0.100 Nitrogen 0.5 -1.5 Chromium 0.1-0.5 Nickel 0.02-0.30 Vanity i 0.01-0.15 Titanium Iron Else (O

Description

The invention relates to ferrous metallurgy, in particular, wear-resistant steels, and can be used as a material for mandrels of pipe piercing mills, non-lining bricks of blast skips and sintering crushers, spikes of sintering machines and other cast parts subjected to friction wear and impact-abrasive wear under the simultaneous conditions of high temperatures and abrasive pressures. At present, in various areas of industry for the manufacture of castings operating under impact-abrasive and It is widely used austenitic high manganese steel 110G13L. If at room temperature and low temperatures, 110G13L steel has a high capacity for strain hardening, it provides sufficient wear resistance under impact and abrasive loads, then at elevated operating temperatures (400–1000 ° C), austenite decomposes with carbides and forms ferrite-carbide mixture and, as a consequence, the loss of wear resistance of steel. Steel 2 containing, in wt.%: 0, is closest to the proposed steel in terms of technical essence and achievable effect. 9-1.5 Carbon 17-23 Manganese 0.2-0.8 Silicon 0.01-0.2 Aluminum 0.002-0.05 0.04-0.4 Iron Rest This steel has a high cold resistance in the deformed state, However, during operation at high pressures, elevated temperatures and the presence of thermocomens as piercing mandrels for pipe mills, the steel has low wear resistance, a tendency to seize with the material of the workpiece and the formation of cracks after flashing one billet, especially when the carbon content is closer to the lower limit (0.9-1.2%). The purpose of the invention is to increase wear resistance under friction and abrasive wear at temperatures up to 600 ° C. This goal is achieved by the fact that steel containing carbon, manganese, silicon, nitrogen, iron, additionally contains chromium, nickel, vanadium, titanium in the following ratio of components, wt.%; Carbon 1.4-1.65 Manganese 17-20 Silicon 0.3-1.0 Chromium 0.5-1.5 Nickel 0.1-0.5 Nitrogen0.002-0.1 Vanadium 0.02-0.3 Titanium 0,01-0,15 Iron Else The increase in carbon content in the proposed steel compared to the known one is due to the fact that the action of high abrasive loads in combination with elevated temperatures leads to de-carbonization of the surface layers of the castings, which can lead to the development of carbon in case of insufficient initial carbon content transformation in the process of aging at high temperatures or subsequent cooling of the surface layers, erozhennyh during casting or heat treatment. The lower limit of carbon content (1.40%) provides for the prevention of the formation of the martensitic or trostitic phase in the decarburized surface layers of the castings. The upper limit of carbon content (1.65%) is determined by the maximum possible content of it in the solid solution (austenite) without the formation of a significant amount of the carbide phase which does not dissolve when heated for quenching, the presence of which promotes the formation of cracks during operation. The narrowing of the cobalt manganese interval in the proposed steel is due to the need to increase the carbon concentration in the steel to 1.40-1.65% and is due to the difficulty of dissolving the carbide phase when heated for quenching. The presence of manganese in the amount of more than 20% in the steel does not allow one to obtain the austenite structure without an allowable amount of doped cementite even with an increase in the quenching temperature to 1150 ° C. Doping the proposed steel with chromium in an amount of over 0.5%, reducing the diffusion mobility of carbon and manganese atoms and increasing the bond energy in austenite, increases the thermal and deformation stability of the solid solution when heated to 1080 ° C surface layers of castings and abrupt heat changes, reduces the tendency austenite to soften at high temperatures, increases oxidation resistance. Increasing the chromium content in excess of 1.5% is impractical, since it causes the formation of insoluble precipitates of doped cementite. The introduction of nickel in the amount of 0.050, 5% stabilizes austenite predla-. steel in relation to decomposition at elevated temperatures. Nickel, the entrance to the solid solution, reduces the tendency to carbidoobrazovaniyu and thermal embrittlement. When the nickel content in the steel is less than 0.1%

its effect on austenite stability and thermal embrittlement becomes insignificant. Increasing the nickel concentration above 0.5% in the proposed steel reduces the strength of manganese austenite for strain hardening and, as a result, the wear resistance of steel, and is also unreasonable for economic reasons.

Co-alloying of steel with titanium and vanadium in an amount of 0.010, 15 and 0.02-0.30%, respectively, reduces the tendency to grow grain when heated for quenching and during friction at high temperatures, and also leads to grinding of the primary structure of cast steel. through the release of titanium carbides (carbonitrides) and vanadium in the process of crystallization and heating for quenching, a. also working surface heating castings. The presence of dispersed carbonitrides in the proposed steel increases the hardness and wear resistance of castings in the process of friction and wear at elevated temperatures, makes it difficult for dynamic recrystallization to prevent softening of austenite.

The content of titanium and vanadium in the proposed steel below 0.01 and 0.02%, respectively, does not cause grain refinement and increase in wear resistance of steel, and an increase in the concentration of titanium and vanadium above 0.15 and 0.3% leads to a decrease in toughness and crack resistance of steel with cyclic heat changes in the presence of abrasive loads.

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Thus, complex alloying with nickel, chromium, titanium and vanadium provides high wear resistance of the proposed steel at elevated temperatures under conditions of abrupt heat cycles in combination with abrasive loads, as well as a low tendency to seizure under high temperature friction compared to the known steel.

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Examples The proposed and well-known steel was melted in a DCM 1.5 electric arc furnace and poured into earth molds for mandrels. Technological purity ferroalloys were used as charge materials.

The chemical composition of the investigated steels is given in table. one.

Table 1

1.40 17.0 0.3 0.5 0.1 0.1 0.01 0.02 1.65 20.0 1.0 1.5 0.5 0.15 0.3 1.55 18.5 0, 6 1.0 0.3 0.1 0.2 Heat treatment of cast mandrels all

steels were carried out according to the mode: exposure to natural gas at a temperature of 1070 ° C for 5 h, followed by cooling in water. This mode provided the austenitic structure in the center of the castings and the austenitic structure with fine globular carbides along the boundaries and body of the austenite grain at the surface of the castings in all steels without signs of decarburization of the surface layer.

The study of steel wear resistance was carried out on casting mandrels with a length of 175 mm and a diameter of 55 mm when flashing blanks from stainless steel 12X18H1OT on an industrial piercer. After flashing one preform, the linear wear of the mandrel was estimated to decrease in length relative to the initial one and the tendency to seizure during friction based on the size of the lining of the preform metal. Availability and. The depth of the cracks was studied on microsections and macrotemplets cut near the working surface. The ability to harden austennte v.prt, the process of high-temperature friction., Was estimated by the increase in the hardness of the working surface of the mandrels. Evaluation of wear resistance under impact-abrasive wear under conditions of high temperatures was carried out on an experimental laboratory crusher with heating of samples using high-frequency current up to temperature. The weight weights of 15 mm samples cut from cast mandrels were measured after grinding 10 kg of crushed granite 4-5 mm. 0.002 Remaining 0.1, 05 –B. 2 shows the data on wear and strength and hardening of the studied tables.

lei when flashing blanks from steel 12X18K10T and impact-abrasive wear.

Table

Claims (1)

M 916579, cl. C 22 C 38/16, 1981. (54) (57) STEEL containing carbon, manganese, silicon, nitrogen, iron, about l and h I am with the fact that, in order to increase wear resistance with friction and abrasive wear at temperatures up to 600 ° C, it thoroughly contains chrome, nickel, vanadium, titanium in the following ratio of components, wt.%: Carbon 1, 40-1, 65 Manganese 17-20 Silicon 0.3 -1.0 Nitrogen 0.002-0.100 Chromium 0.5 -1.5 Nickel 0.1 -0.5 Vanadium 0.02-0.30 Titanium Iron 0.01-0.15 ° The rest is L one V / s n * and*