SU742481A1 - Cast iron - Google Patents

Description

(54) CAST IRON

This invention relates to the field of metallurgy, in particular, to cast irons used to manufacture wear-resistant bleached parts, for example, wear-resistant replaceable parts of metalworking and mining equipment. The closest to the invention in technical essence and the achieved effect is cast iron 1 of the following chemical composition, wt.%: Carbon2.2-3.4 Chromium5.0-6.5 Silicon 2.8-3.5 Aluminum 1.0-1 , 5 Manganese 0.6-2.0 Iron Others As an impurity, iron contains sulfur up to 0.2 wt.% And phosphorus up to 0.15 wt.%. This alloy represents a eutectic cast iron, the structure of which in the bleached (rapidly cooled) casting layer is characterized by eutectic based on hexagonal chromium carbide - (Cr, Fe) - Cz, and in the gray (slowly cooled) layer - - graphite eutec and has the following mechanical characteristics in the cast state: Strength at stretching 2 37-39 kgf / mm, of the bleached layer Impact strength of 0.2 kgf M / mm; bleached layer Hardness of the bleached layer at a depth of 10 mm from po410-520 HB; surface Sulfur hardness 320-370 HB. eons of this, high hardness in the named areas of the casting, causing their breakage. The purpose of the invention is to reduce hardness in slowly cooled parts of the casting and to increase the hardness and wear resistance in the rapidly cooled NUDC parts of the casting. This is achieved by the fact that cast iron containing carbon, silicon, manganese, chromium, aluminum, and iron additionally contains molybdenum, vanadium, copper, nickel, cerium and calcium in the following ratio of components, wt.%:

Carbon1.8 -3.6

Silicon3.0-3.5

Manganese 0.2 -5.0

Chrome3.5 -4.9

Aluminum 0.01-0.8

Molybdenum 0,01-1,2. Vanadium 0.01-0.5 Copper0.1 1.8

 Nickel0.1-0.5 Cerium0.01-0.3

Calzgy 0.01-0.3

Iron Else.

As impurities, cast iron contains sulfur in an amount of 0.05–0.1 wt.% And phosphorus 0.03–0.1 wt.%.

The indicated concentration ranges of the components are chosen in view of the following.

Carbon - minimal (1.8%) concentration is chosen so that at any ratio of the other components, at a solidification rate of 0.2 ° C / s, to ensure the formation of a gray zone of the casting with austenite-graphite eutectic with reduced hardness; maxi-. small (3.6%) - should provide the highest wear resistance of the working (bleached) part of the casting.

Chromium - the minimum (3.5%) concentration ensures the formation of eutectics based on hexagonal chromium carbide in the bleached part of the casting at the minimum (1.8%) concentration of carbon, and the maximum (4.9%) concentration of chromium ensures that at the maximum (3 , 6%) carbon concentration in the alloy.

Silicon - within the specified limits (3.0–3.5%) contributes to the formation of eutectics based on hexagonal chromium carbide in the bleached part of the casting at any concentrations of carbon, and also contributes to the formation of austenite-graphite eutectic in the gray part of the casting; A run of 0.5% between the limiting concentrations is chosen to simplify the alloy smelting technology.

Aluminum - the minimum concentration (0.01%) clears the grain boundaries of the alloy during crystallization, contributing to the uniformity of properties over the cross section of the bleached part of the casting, and the maximum (0.8%) concentration enhances the effect of silicon.

Manganese - minimal (0.2%) concentration selected as a usual technological admixture of iron-carbon alloys; the maximum (5.0%) concentration contributes to the stabilization of the solid solution during disintegration, ensuring that c. depending on the operating conditions, higher service resistance of bleached castings.

Molybdenum - the minimum (0.01%) concentration acts in the same way as the minimum (0.01%) aluminum concentration; The maximum (1.2%) concentration increases the hardenability of the alloy solid solution, increasing the hardness over the depth of the bleached casting zone.

Copper - minimal (0.1%) concentration selected as a technological admixture of iron-carbon alloys; the maximum (1.8%) concentration ensures the doping of the solid solution, thus increasing its strength properties.

Nickel - within the specified limits (0.1-0.5%) with an increased content of molybdenum provides in the bleached zone of the casting the decomposition of the solid solution into high-hard and wear-resistant martensite.

Vanadium, cerium, and calcium - at the named limits, have a modifying effect, contributing to the grinding of grains and the purification of their boundaries, and thereby increase the viscosity of the alloy.

Sulfur and phosphorus - within the specified limits are selected as ordinary technological impurities of iron-carbon alloys.

To determine the hardness and wear resistance, alloys were melted, the contents of which are given in Table. one.

The cast iron was smelted in an open induction furnace in the main crucible. In order to simulate the solidification conditions of the bleached casting zone, casting of cast iron was carried out in quartz tubes 10-12 mm in diameter, 1000 mm long, installed in a vertical tube furnace at a temperature of 900s, where crystallization took place. Samples obtained from similarly obtained castings were used to determine hardness and wear resistance.

In order to determine the hardness in the slowly cooled parts of the bleached casting (in the gray zone), part of the smelted cast iron was crystallized at a rate of approximately 0.2 ° C / s, observed, for example, at the core and necks of large mill rolls.

The wear resistance of the bleached layer was studied under conditions of friction between metal and metal with slippage, and the model conditions of the work of mill rolls. The material of the control Sample served as Art. 3. Other things being equal, the load on the sample was 100 kg. The friction zone was cooled with running water.

The hardness and wear resistance of the proposed and known cast iron are given in table. 2

As can be seen from the above data, the hardness and wear resistance of the proposed alloy in the bleached part of the casting is much higher, and the hardness in the gray part of the casting is much lower compared to the known alloy.

The specified characteristics of the proposed cast iron / presumably by 30% increase the service life of wear-. resistant bleached castings. This is position 1.80 3.49 3.15 0.014 0.31 0.019 0.180 2 2.84 4.28 3.49 0.020 1.12 0.690 0.780 3 3.58 4.81 3.44 0.770 4.82 1.110 1.720

Prototype 2.81 5.67 3.12 1/230 0.87

0.0387 44-53 415-525 22-28 228-269

0.0312 49-61 477-627 25-30 249-285

0.0294 54-63 532-652 25-32 249-297

Prototype 0.0448 42-48 392-460 35-38 320-351

Claims (1)

Invention Formula Cast iron containing carbon, silicon, manganese, chromium, aluminum and iron; characterized in that, in order to reduce the hardness in the slowly cooled parts of the casting and to increase the hardness and wear resistance in the rapidly ossified parts of the casting, it additionally contains For example, at the Dnepropetrovsk, iron and steel processing plant, which produces about 20,000 tons per year. Bleached sheet-making rolls, save 6,000 tons of waste, with an economic effect of approximately 250000 rubles. The smelting technology of the proposed alloy does not vary compared with that used for the known alloy. Table 1 0.06 0.04 oci: table 2 molybdenum, vanadium, copper, nickel, cerium and calcium with the following ratio of components, wt.%: Carbon1 8 -3.6 Silicon3.0 -3.5 Manganese 0.2-5.0 Chrome3.5-4.9 Aluminum 0.01-0.8 Molybdenum 0,01-1,2 Vanadium 0,01-0,5 0,1080,011 0,012 0,017 0,0f 0.03 ost 0.3500,2900,130,0,170 0.06 0.03 ost 0.4700,4300,2600,2900,09 0, 06 stop Y1,0,1 -1,8 Nickel 0,1 -0,5 Cerium 0,01-0,3 Calcium 0,01-0,3 IronEverything else 7424818 Sources of information taken into account during the examination 1. USSR author's certificate 240260, cl. C 22 C 37/06, 1967 (prototype).