SU1089162A1 - Cast iron - Google Patents

Abstract

CAST IRON containing carbon silicon, manganese, chromium, nickel, yttrium and iron, characterized in that, in order to increase wear resistance, it additionally contains cerium in the following ratio, wt.%: Carbon 2.8-3.5 Silicon1 , 3-2.5 Manganese 0.5-0.8 Chromium 0.2-0.6 Nickel. 0, 6 Yttrium0.02-0.07 Cerium0.04-0.08 IronEstal

Description

The invention relates to metallurgy, and more specifically to the search for thermally wear-resistant and high-strength cast irons for casting rolls.

Known cast iron l chemical composition, wt.%:

2.80 ... 3.30 Carbon Oh, 50 ... 1.20 Silicon Oh, 50 ... Oh, 80 Manganese Oh, 04 ... Oh, 08 Cerium 0.02 ... Oh, 07 Yttrium The rest of the iron

Cast iron has low strength properties and wear resistance.

The closest in technical essence to the present invention is cast iron 2 composition, wt.%: Carbon 3,4-3,8

Silicon1,5-4

Manganese 0.49-1.09 Chrome. - up to 0.35 Nickeldo O, 1

Yttrium0.03-0.54

IronErest

Cast iron has satisfactory strength properties. A disadvantage of the known cast iron is low wear resistance.

The purpose of the invention is to increase the wear resistance of cast iron.

The goal is achieved by the fact that cast iron containing carbon, silicon, manganese, chromium, nickel, itrium and iron, additionally contains cerium and its components taken in the following ratio, wt.%: Carbon 2.80 ... 3.50

Silicon1.30 ... 2.50

Manganese Oh, 50 ... Oh, 80 Chrome. Oh, 20 ... Oh, 60

Nickel, 80 ... 1.60

Yttrium. 0.02.,. .0,07 CeriOO 04 ... O, 08

IronErest

The introduction of cerium and an increase in the nickel content determine a decrease in the amount of ledeburite (a more plate-like eutectic appears) and an increase in the degree of dispersion of auste, nit (decompression products) (P 0.25 - Pd 0.3).

Increasing the carbon concentration above 3.50% leads to the appearance of a significant amount of the carbide phase in the structure, which ensures a hardness, but reduces viscosity, leading to cracking and chipping of the working layer.

At carbon contents below 2, the viscosity increases due to an increase in the content of the plastic high iron phase in the structure. This reduces wear resistance and sharply deteriorates casting properties (fluidity, shrinkage).

Silicon within these limits is designed to compensate for the effect of oxidation of individual components of the melt, neutralizes the carbidizing effect of chromium, i.e. provides obtaining the necessary degree of graphitization of cast iron (Kg). An increase in the silicon content above 2.50% leads to a decrease in physicomechanical and special properties. With a decrease in silicon content of less than 1.30%, the graphitization parameter (Kg) is low, and therefore a lot of cementite is added to the structure of the roll necks and a looseness of metal is observed.

Manganese within O, 50 ... O, 80% promotes the desulfurization and deoxidation of pig iron, and allows you to adjust the structure of the metal matrix. With an increase in its content of 0.80% enlarged grain, transcrystallinity appears in the cast iron macrostructure, the amount of cementite increases. Decreasing the manganese content of less than 0.50% decreases the physicomechanical and special properties.

Chromium is the main regulator of hardness (wear resistance) of iron, guna. As its concentration increases within the chosen limits, the microhardness of cementite increases due to an increase in the degree of doping with chromium. At concentrations above 0.60%, the hardness of the roll necks increases so much that their mechanical processing is very difficult.

 When the chromium content is less than 0.20%, its effect on the microhardness of cementite is insignificant.

Nickel contributes to an increase in the degree of dispersion of austenite decomposition products. When the content is less than the lower limit of this effect, nickel is not observed, and graphite inclusions appear in the cast iron structure, which leads to a decrease in wear resistance. An increase in the nickel content within 1.61 ... 3.00% does not lead to significant structural changes, therefore from an economic point of view we limit the upper limit of the nickel content to 1.60 Cerium and yttrium in the specified limits contribute to the dispersion of the matrix, reducing the size of carbides, which entails an increase in wear resistance. With an increase in the content of cerium and yttrium above the upper limits, a large number of nonmetallic inclusions, which reduce the special properties of cast irons, occur. When the content is below the lower limits, cerium and yttrium are consumed only for melt refining. The cast iron is melted in an LPZ-67M acid-lined induction furnace. Modifying elements (cerium, yttrium) are introduced into the ladle before the metal is released in the form of cerium-yttrium ligzture. Chromium and nickel are introduced into the furnace. The cast iron at ISOOi-S C is released into the ladle with the necessary weight of modifiers and when it reaches 1330 ... 1340 °, it is poured into a chill mold. Castings have dimensions: diameter 50 mm, height 200 mm. Samples are cut out from castings for chemical analysis, metallographic studies, measurements of hardness, determination of chemical composition, wt.%

IjLJ ..... -.- J. ±. -J -... l: 2 strength and flexural strength and wear resistance. Wear resistance tests were carried out on an SMC-2 machine with friction-slip with a load of 75 kg. Testing of mechanical properties is carried out on samples according to GOST 1A87-73. The chemical composition and test results are shown in Tables. In Table. 1 shows the chemical composition of cast iron, in table. 2 - properties of cast iron. As can be seen from the table for wear resistance, the described cast iron is superior to lime iron. To test the results of the experimentation in the roll-up shop, an experimental batch of rolls of cast iron of the proposed composition was cast. The properties of the experimental waltzes were compared with the properties of the current production rolls (base object). The use of rolled Hbix cast iron rolls for casting of the proposed composition makes it possible to increase their durability by 15 ... 20%. The estimated need of the national household in the rolls cast from the proposed iron is ZOObO. The economic effect at the maximum amount of use will be 87,669 rubles / year. : Table 1

table 2

0.045

44

0.038

47.5

five

0.04

46

0.036

50

five

0.04

48

0.04

42

0.049

42

0.3 0.3 0.3 0.2 0.3 0.5

Claims (2)

CAST IRON containing carbon * silicon, manganese, chromium, nickel, yttrium and iron, which differs in that, in order to increase wear resistance, it additionally contains cerium in the following ratio, May. %: Carbon Silicon Manganese Chrome Nickel Yttrium Cerium Iron 2.8-3.5 1.3-2.5 0.5-0.8 ' 0.2-0.6 0.8-1.6 0.02-0.07 0.04-0.08 Rest N3>