SU1611972A1 - Cast iron - Google Patents

Abstract

The invention relates to metallurgy and can be used in the manufacture of parts operating under conditions of impact abrasive wear. The purpose of the invention is to increase the abrasive resistance and fluidity. Cast iron contains components in the following ratio, wt.%: C 1,8-3,2

SI 0.4-0.9

MN 0.2-0.95

CR 26-29

NI 0,2-5

TI 0.05-0.3

V 0.05-2

BA 0.01-0.03

FE the rest. The addition of barium to the composition of cast iron makes it possible to increase the abrasive resistance by 1.17-1.23 times and the fluidity by 1.1-1.14 times.

Description

The invention relates to metallurgy, in particular, to the development of cast iron compositions for the manufacture of parts operating under conditions of impact abrasive wear.

The purpose of the invention is to increase the abrasive resistance and fluidity.

The choice of boundary limits, the content of KOMrtoHeHTOB in the Iron, of the proposed composition is determined by the following.

Carbon in the amount of 1.8-3.2 wt.% Is introduced into the alloy dd forming wear-resistant carbides and providing the necessary fluidity. When the carbon content of 1.8 wt.% Dramatically decreases the fluidity and the number of carbides, which reduces abrasion resistance. When the carbon content in the alloy is more than 3.2 wt.%, A release is observed. large hypereutectic carbides that reduce the mechanical properties

and abrasion resistance due to their vykra-, shivani.

Silicon in the specified concentration range is used to regulate the degree of eutecticity of iron, which determines its casting properties and microstructure. When the silicon content is less than 0.4 wt.%, The casting properties of the alloy decrease and the tendency of the alloy to form shrinkage defects increases. With an increase in silicon (more than 0.9 wt.%), The eutectic component is enlarged, which leads to a decrease in dynamic strength.

Manganese in the range of 0.2-0.95 wt.X performs the role of an element that prevents & red brittleness. Manganese converts sulfur to MnS fine sulphides from T.Sh1. 1610 ° C, which are located during the crystallization of the alloy inside the zef

WITH

| Yu

ren. Manganese content less. 0.2 wt.% Does not significantly affect the properties of the alloy, as it becomes an impurity. An increase in manganese content (more than 0.95 wt.%) Leads to the formation of columnar crystals and a decrease in plastic properties.

Chromium in the proposed amounts is seated in the alloy to ensure the formation of a chromium-doped matrix of increased microhardness of chromium-carbide eutectics based on hexagonal chromium carbides and finely dispersed carbide phase (Fe). maintaining a high dynamic strength. When the chromium content is less than 26 wt.%, cubic chromium carbide () begins to be absent, hardness decreases and the abrasion decreases. oykoSt. When chromium content of more than 29 wt.% and is by-phase selection which is accompanied by a sharp increase in volume and consequently the internal stresses. Furthermore, this compound embrittle the alloy.

Nickel in the indicated amounts increases the stability of austenite at eutectic transformation temperatures. By introducing nickel up to 5 wt.%, The maximum hardness of the pig iron is achieved due to the formation of a significant amount of martensite. When the nickel content is less than 0.2 wt.%, The hardness of the products decreases both in the cast state and after heat treatment, which leads to a decrease in abrasion resistance. When the nickel content is more than 5 wt.%, Austenite is stabilized and its amount increases in the structure after heat treatment. Residual austenite leads to a decrease in hardness and, accordingly, abrasion-resistant.

Titanium in these quantities provides the binding of nitrogen in a liquid melt to nitrides, which increases the plastic properties of cast iron. With a content of less than 0.05% by weight, titanium does not significantly affect the properties of the alloy. In the presence of titanium more than 0.3mas. Titanium carbides have been observed, the release of which is noted on

the boundaries of austenite dendrites, which leads to a decrease in the dynamic strength of the alloy.

Vanadium in the proposed concentration range is a modifying and alloying element that grinds the microstructure and forms highly hard special carbides, which leads to high abrasion resistance of cast iron. With a vanadium content of less than 0.05 wt.%, The described effect is not observed in high-chromium iron. If the vanadium content is more than 2 wt.%, The crystallization interval of the alloy increases due to the formation of primary vanadium carbides at the early crystallization stage and, accordingly, the dynamic strength decreases due to the increase in microdefects of shrinkage origin.

Barium in the proposed cast iron is introduced in an amount of 0.01-0.63 wt.% To reduce the formation of captivity and remove sulfur, which significantly increases its fluidity, which is especially important for lining plates of complex configuration. When the content in the alloy is less than 0.01 wt.%, Barium has a significant effect on its fluidity, and when it is more than 0.03 wt.%, The effect of reducing chromium oxides decreases due to the formation of barium oxides, which also lower the fluidity.

In the development of the chemical composition of the proposed cast iron, the metal is smelted in an HCT-Oj06 furnace with an acid lining according to the generally accepted technology.

Three mixtures of ingredients were prepared, in which the content of the components was at the lower, middle and upper limit. At the same time, alloys are melted at the lower limit, the average content and the upper limit of the chemical elements of the prototype.

Each mixture is fused separately. Ferro-manganese is used to introduce the required chemical elements into the alloy; manganese is consumed in an acid lining furnace with 34%; ferrochrome, chromium burn 5%, vanadium, vanadium burn, was 42%, sponge titanium, and titanium waste 41.5%. kobarium forces (bari 22%, silicon 35%, the rest iron), barid barrels - 56%, nickel, barren nickel 1%.

V 161

Ferrochrome is placed in the crucible of the furnace together with the charge, ferromanganese, vanadium, titanium and nickel in the molten metal at 1380-1. After overheating of the alloy to 1450-1480 ° C and holding in the furnace for 5-10 minutes, the metal is released into the ladle, at the bottom of which there is a silo-barium heated to 500 ° C. The metal temperature is measured by a platinum-platinum-rhodium immersion thermocouple.

19726

The fluidity is determined by the length of the poured spiral (L), at a temperature of the cast metal of 1320 C.

J The test results are shown in the table.

The data obtained indicate that the proposed cast iron has greater fluidity (at

0 10-14%) and abrasion resistance (17, 24.3%) compared with the known.

Claims (1)

Claim 15 Cast iron containing carbon, silicon, manganese, chromium, nickel, titanium, vanadium and iron, it is easy to use, in order to increase abrasion resistance and fluidity 20, it additionally contains barium with the following content components, wt.%: Carbon 1.8-3.2 Silicon 0.4-0.9 25 Manganese 0.2-0.95 Chromium 26-29 Nickel 0.2-5.0 Titanium! 0.05-0.30 Vanadium 0.05-2.00 thirty Barium 0.01-0.03 Iron Rest Fluid flow Abrasion resistance (weight loss), g / m ² .h Proposed 1 1.8 0.4 0.2 26.0 0.2 0.05 0.05 0.01 - 71.29 0.337 716 2 2,5 0.6 0.5 27.5 2,5 about; is 1,03 0.12 - 65,2 0,303 750 3 3.2 0.8 0.95 29.0 5,0 0.3 2.0 0,03 - 58.72 0.255 762 4 1.7 0.3 0.1 25.5 ο, ι 0,03 0,03 '0.005 - 72,235 0.344 708 5 sz 0 1, 01 29.4 5.2 0.34 2.6 0,035 - 57,215 0.270 760 Famous ny 6 2,8 0.9 0.3 12 0.8 0.08 0.2 - 0.3 82.62 0.448 506 7 3.04 1.12 0.40 14.2 0.97 0.53 0.26 - 0.4 79.08 0.42 9 521 8 3.2 1.3 0.5 16 1,11 0.12 0.30 - 0.5 76.97 0.388 562