SU1337434A1 - Cast iron with specific graphite - Google Patents

Abstract

The invention relates to the field of metallurgy, in particular to wear-resistant cast iron with vermicular graphite for the production of shell-type wall castings. The aim of the invention is to increase the hardness, wear resistance and penetration of the structure in the sections of differential castings. The proposed cast iron contains, in wt.%: Carbon 3.2-3.6; silicon 2.6-3.0; manganese 1.0-2.0; chromium 0.05-0.25; Nickel 0.2-0.6; titanium 0.02-0.08; aluminum O, 01- 0.05; REMO, 1-0.15; boron 0.04-0.08; Calcium. O, 005-0.05; barium 0.005-0.02; iron else. The use of the proposed cast iron makes it possible to increase the hardness of the cast irons by 20-30 units. according to Brinell, wear resistance by 15-20%. 2 tab. (L with so 4 :: CO 4

Description

The invention relates to metallurgy, in particular to the search for wear-resistant cast irons with vermicular graphite, possessing the required level of mechanical and technological properties in a molten state for the production of case differential castings, for example, for metal-cutting machines operating under conditions of sliding friction lubricant.

The aim of the invention is to increase the hardness, wear resistance and leveling of the structure in the sections of differential castings.

The proposed cast iron, mainly for castings with a wall thickness of 20-100 mm, contains carbon, silicon, manganese, chromium, nickel, titanium, aluminum, rare-earth metals, boron, barium, calcium and iron in the following ratio of components, wt.%:

Carbon

Silicon

Manganese

Chromium

Nickel

Titanium

 Aluminum RZM Bor Calcium

Barium cast iron in

quality

3.2-3.6 2.6-3.0

1.0-2.0 0.05-0.25

0.2-0.6 0.02-0.08

0.01-0.05 0.1-0.15 0.04-0.08 O, 005-0.05 0.005-0.02 impurities can sulfur - to

contain phosphorus up to 0.1%, 0.015%.

The chemical composition of the alloys is given in tab. one.

Carbon in the range of 3.2-3.67, provides good casting and mechanical properties of cast iron. The lower limit of carbon is due to the need to exclude structurally free carbides in the alloy. Increasing the carbon concentration above 3.6% worsens the shape of the graphite inclusions. Thus, a carbon concentration of 3.2–3.6% is optimal.

A silicon concentration of 2.6-3.0% facilitates solidification of the alloy according to a stable state diagram without structurally free carbides and ensures good casting and mechanical properties of cast iron. The lower limit for silicon is set on the basis of the requirements for eliminating chill in castings with a thickness of 20 mm. the upper limit of silicon is somewhat lower

plastic and strength properties of cast iron.

The introduction of the cerium group in the REM in an amount of 0.1-0.15% contributes to obtaining vermicular graphite. The lower limit of the content of rare-earth metals is due to the need for deacidification and partial desulfurization, which contributes to the formation of the vertical form of graphite. The upper limit is limited by an increase in the tendency of pig iron to chill and an increase in the proportion of spherical graphite.

0

Aluminum in an amount of 0.01-0.05% is introduced to further deoxidize the molten iron, increase the stability of the formation of vermicular graphite and reduce the tendency of the iron to chill. The upper limit of the aluminum content is chosen from the condition of its optimal influence as a graphitizing and de-5, spheroidizing element. The introduction of aluminum into the molten iron above the established limit leads to the formation of an oxide film of aluminum, which reduces the technological properties of black guna. The introduction of aluminum below 0.01% has practically no noticeable effect on the structure of cast iron.

The titanium content of 0.02–0.08% in cast iron contributes to the improvement and stable formation of the vermicular form of graphite. Introduction of titanium to cast iron above a set limit can lead to the formation of lamellar graphite and a decrease in mechanical properties.

In order to ensure high hardness and wear resistance of the proposed cast iron in comparison with the known composition, alloying elements are contained in its composition: chromium, nickel, manganese, boron.

Content}: 0.05-0.25% rum in cast iron is selected from the following conditions: the lower limit is usually provided when smelting cast iron on any charge materials, and the upper limit is set to ensure an increase in the hardness and wear resistance of the cast iron and to produce 20 mm thick without chill .

A nickel concentration of 0.2–0.6% contributes to an increase in the hardness and wear resistance of cast iron, as well as to the alignment of the metal base in different castings. Introduction of nickel into

0

five

0

five

These limits have the strongest effect on the structure and mechanical properties of cast iron. A further increase in nickel introduction is impractical from an economic point of view.

The manganese content in the pig iron is 1.0-2.0% selected in view of ensuring the high content of perlite in the metal matrix to increase hardness and wear resistance. As is known, when the content of manganese is more than 1.0%, its influence on the cast iron structure is quite intense. When manganese is introduced to more than 2.0%, the cast iron crystallization proceeds with a significant release of structurally free carbides that cannot be eliminated due to the introduction of graphitizing elements.

The introduction of boron in cast iron containing alloying elements (manganese, chromium, nickel) in an amount of 0.05-0.08% contributes to the perlithization of the metal matrix of cast iron and increases the uniformity of its distribution over the cross section of differential castings, which allows to increase the hardness and wear resistance of cast iron . When the concentration of boron is more than 0.08%, chill iron is picked up, which cannot be eliminated due to the introduction of graphitizing modifiers containing Ba, Ca, A1. When the boron concentration is less than 0.04%, its effect on the structure and properties of cast iron is insignificant.

Barium at a concentration of 0.005-0.02% contributes to the crystallization of cast iron without structurally free cementite in thin-walled castings and increases the uniformity of distribution of the metal matrix over the cross section of differential castings. Increasing this limit of barium content leads to the opposite effect, i.e. Barium promotes the formation of free carbides, and the introduction of it into cast iron below 0.005% does not substantially change the structure and properties of cast iron.

Calcium at a concentration of 0.005-0.05% improves vermi-. Cluster forms of graphite, increases the stability of the process of modifying pig iron. With the introduction of calcium above 0.05%, its absorption by liquid iron deteriorates and contributes to the formation of non-metallic inclusions, which reduce the mechanical properties of the iron.

The introduction of calcium below 0.005% does not significantly affect the structure and properties of cast iron.

ten

15

74344

The structure of the proposed iron has a pearlitic-ferritic metaplastic matrix and compact inclusions of vermicular graphite.

Example. Melting of cast iron was carried out in a high-frequency induction furnace with an acid stuffed lining with a crucible capacity of 60 kg. As the source materials used: linear and pig iron pigs, waste carbon steel. In order to ensure the required chemical composition, ferroalloys were introduced into the molten iron at a temperature not lower than 1450 ° C: ferrosilicon FS 45, ferromanganese FMN 75, ferroboron FB 17, ferronickel foundry FN 6, ferrotitanium Fti 30, aluminum AB 98.

Spheroidizing modification was carried out in order to obtain the vermicular form of graphite in cast iron. At 1450-1480 C, 0.8-1.0% of the modifier FS 30 REM GOF was introduced into the metal mirror in the furnace with a fraction of 2-15 mm and kneaded it into the molten iron until complete dissolution.

To reduce the chill off of the cast iron in thin sections of castings, the molten cast iron before pouring into the molds was subjected to graphitizing modification in the ladle at 1380-1400 ° C. At the same time, ferrosilicon FS 75 was used as a modifier for the known composition of cast iron, and silico-calcium SC 20 and ferrosilicon with barium FS 60 BA 22 were used for the proposed pig iron.

To obtain prototypes: a wedge on a chisel, a trefoil of differential samples with a cross section of 20 g - 20, 60 60, 100 100 mm and a length of 300 mm, the casting molds were cast with known and proposed cast iron.

Claims (1)

The tensile strength for cast iron was determined on standard samples, the structure of the metal base, hardness and wear resistance were determined in blanks of different reduced thickness. The wear resistance of the known and proposed cast iron was determined by sliding friction with contaminated lubricant. Cast iron and white electrocorundum, 50% of each name, was used as a contaminant. The amount of contamination was 2/3 of the volume of industrial oil. Samples of cast iron were tested on an installation that allows the cast iron structure and an increase in chipping. 5133743D6 TITLE CONDITIONS FOR WORK OF MACHINE TOOLS FOR THE APPLICATION OF CEMENTITE IN ZOVYI OF PARTS. Specific pressure on the samples was 10 kgf / cm, movement speed was 0.06 m / s, test time was 30 minutes. Measurement of the amount of wear of the specimen-Cast iron with vermicular graphite was determined by weighing (before castings containing carbon, cream and after testing) for analytical, manganese, chromium, nickel, titanium, scales with an accuracy of 0.0002 g. - IQ apkminium and iron, distinguishing the units of wear resistance of cast iron u and with the fact that, in order to increase the adopted dimension of g / h. The results of neither hardness, wear resistance, and test results are given in Table. 2, the structure equals in the sections of the section. Analysis of the results of the determination of wall castings, it additionally shows the structure and properties of cast iron; it contains rare-earth metals, boron, therefore, with optimum content of barium and calcium at the following manganese 1.0-2, 0% additional wearing of components, wt.%: Input of boron with calcium and carbon additives 3.2-3.6 ri (smelting 1-3) contributes to the perlitization of the metal base of cast iron, 20 removes hardness and wear resistance. With an increase in the manganese content of e. Or boron in the composition of cast iron (smelting 5 and 7), inclusions of cementite appear in the structure of cast iron, chillings increase, which is a negative factor and reduces the workability of cast iron in thin-walled castings. Decreased calcium or Silicon Manganese Chromium Nickel Titanium Aluminum Rare earth metals 0.1-0.15 Bor0.04-0.08 Calcium 0.005-0.05 Barium 0.005-0.02 2.6-3.0 1.0-2.0 0,0.5-0,25 0.2-0.6, 0.02-0.08 0.01-0.05 bari in cast iron (smelting 4) also iron 3,23,23,43,6 2,62,62,83,0 0,81,01,52,0 0,050,050,150,25 0.20.20.40.40 0,020,020,050,08 0,010,010,030,05 , 0,10,10,120,15 -0,040,060,08 -0,0050,0270,05 0,0050,0120,02 the structure of cast iron and increased chill. Invention Formula it has cementite Cast iron with a vermicular graph of castings containing carbon, manganese, chromium, nickel, minium, and iron is also different in that, for the purpose of hardness, wear resistance of the structure in sectional castings, it adds rare earth metals and calcium in the following component, wt.%: Carbon 3.2-3.6 Silicon Manganese Chromium Nickel Titanium Aluminum Rare earth metals 0.1-0.15 Bor0.04-0.08 Calcium 0.005-0.05 Barium 0.005-0.02 2.6-3.0 1.0-2.0 0,0.5-0,25 0.2-0.6, 0.02-0.08 0.01-0.05 Rest Table 1 CNl 00 rt i s t Yu CO H ABOUT vO oo r Oh oh CNl about if) F about sh m s sp in s to vr g-CS1 00ЮП about SP OOSG 1L "- Ti r t vO in about s-h -3 cm cs cm about R - Ltd YU with g oh oh oh f t cho about oo about - about Ltd CM about R cm about 1L about oh oh 00 about LO about r CM about about about about cm  - about N about oh oh YU about CN | about 1L about (U 0) R. P) with t