SU1602880A1 - Cat iron - Google Patents

Abstract

The invention relates to metallurgy and can be used in the manufacture of body parts. The purpose of the invention is to improve the mechanical properties. New cast iron contains, wt%: C 3.1-3.6

SI 1,8-2,6

MN 0.6-1.1

AL 0.01-0.2

CU 0.05-0.8

CR 0.02-0.45

V 0,005-0,15

NI 0.05-0.3

N 0,008-0,045

TI 0.01-0.2

CO 0,008-0,06

one element from the group containing CA, BA and SR 0.01-0.08 and FE the rest. An additional input of the proposed iron TI, CO, as well as a group or BA SR allowed _to increase in σ 1,16-1,27 times, HB at 1,13-1,31 times shock fatigue strength in 1, 21-1.34. 2 tab.

Description

The invention relates to metallurgy, in particular to the development of cast iron compositions for casting body parts.

The purpose of the invention is to improve the mechanical properties.

The invention is illustrated by examples of specific performance.

The choice of the boundary limits for the content of components in the pig iron of the proposed composition is determined as follows.

Entering carbon into the cast iron contributes to a decrease in its melting temperature and provides a modifying effect, leading to solidification of the metal without structurally free cementite. Optimal with. The carbon retention in the cast iron of this composition should be in the range of 3.0-3.6%. If the carbon content is less than 3.0%, structurally free Cementite appears in the structure and this leads to a decrease in strength properties and an increase in the level of residual stresses, and if the carbon content is more than 3.6%, then an increase in the size of the cast iron is observed. and the deterioration of the shape of graphite inclusions, which also reduces the strength and operational properties of cast iron.

Silicon is introduced into the composition of cast iron as a modifier and its optimum content should be in the range of 1.8-2.6%. With the content

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silicon less than 1.8% in the pig iron appears chill and cracks and wefts are possible. With an increase in the silicon content of more than 2.6%, the graphite inclusions are large in size, ferrite appears in the metal matrix, which leads to the formation of a ferrite rim around the graphite inclusions and a decrease in strength

properties, especially impact-fatigue strength.

Manganese in cast iron contributes to the perlitization of the metal matrix. Its optimal content is in the range of 0.6-1.1%. If the manganese content is less than 0.6%, then ferrite appears in the cast iron microstructure and the strength properties decrease, and if its content is more than 1.1%, structural-free cementite is impacted and the impact fatigue strength of the iron decreases.

Aluminum is introduced in-cast iron as a strong modifier. Its action as a modifier begins to appear at a content of 0.01% or more. With an increase in the aluminum content of more than 0.2%, the appearance of alumina films is observed, which leads to a decrease in the strength properties.

Entering into the composition of cast iron copper contributes to an increase in the fluidity of the metal and perlitizes the metal matrix of cast iron. Her positive

the effect on the fluidity, microstructure and properties of cast iron is manifested when the copper content in the cast iron is in quantities of 0.05% and more. With an increase in the copper content of more than 0.8%, a further increase in the flowability and properties of cast iron is significant. but slower.

Chromium is introduced into the composition of cast iron in order to perlitize the microstructure and increase the dispersion of perlite. The positive effect of chromium as a perlization agent begins to appear when it is contained in iron in quantities of 0.02% and more. With an increase in chromium containing more than 0.45%, structural-free cementite appears in the cast iron microstructure and the strength properties decrease.

The introduction of titanium iron in amounts of 0.01-0.2% leads to an increase in the effect of modifiers and a reduction in size, to an improvement in shape.

graphite inclusions. The positive effect of titanium on the microstructure and the properties of cast iron begin to manifest when the titanium content is in quantities of 0.01% or more. An increase in the titanium content of more than 0.2% does not lead to a further improvement of the microstructure and an improvement in the properties of the iron.

The bathdium is introduced into the composition of cast iron as a strong perlithizer, a higher dispersion of perlite and, accordingly, an increase in the fatigue strength of the cast iron. The optimal vanadium content in the cast iron of this composition should be in the range 0.005-0.15%. The positive effect of vanadium on the polymerization of the microstructure begins to appear when it is contained in iron in amounts of 0.005% or more. With an increase in vanadium content of more than 0.15%, structural-free cementite appears in the microstructure of cast iron, and fatigue strength decreases cast iron, the level of residual stresses increases and the geometrical and dimensional accuracy of castings decreases.

Nitrogen is a strong perlizer, contributing to a significant increase in the strength properties of cast iron. A marked improvement in the strength properties of cast iron is observed at a content of 0.008% nitrogen and more.

When the iron contains more than 0.045% of nitrogen in the castings, gas shells appear, caused by the release of nitrogen during the process of solidification of the cast iron, which leads to the rejection of the castings.

Introducing nickel and cobalt into cast iron contributes to lowering the strength properties of the metal matrix of the microstructure. precision castings. This is due to the positive effect of nickel atoms on increasing the strength bonds in the lattice of iron-carbon alloys and reducing the effect on the graphitization process of these alloys on the cooling rate. The total nickel content in the cast iron of this composition should be in the range of 0.05-0.35%. Improving the properties of cast iron

starts to appear when the content of nickel in the metal in quantities of 0.05% and more. With an increase in the nickel content of more than 0.35%, its positive effect on the deterioration of the strength and performance properties of pig iron appears weaker and becomes economically disadvantageous.

Cobalt affects the properties of cast iron in a manner similar to nickel. Since it is an accompanying nickel element, its content in the iron is determined by the nickel content. Its positive effect on the properties of cast iron begins to appear when it is introduced into cast iron in quantities of 0.008% and more. Upon reaching 0.06% cobalt in the iron, the maximum increase in the strength properties of the iron is observed, and with: a further increase in the cobalt content, a slight increase in the strength properties of the iron is observed.

Entering into the composition of cast iron elements from the group containing calcium, barium and strontium, which are strong modifiers, helps to improve the shape and reduce the size of graphite inclusions. Together with nickel and cobalt, they contribute to obtaining an optimal microstructure of cast iron, which provides superior strength properties, especially impact-fatigue strength, a decrease in the level of residual stresses and an increase in the geometrical and dimensional accuracy of body parts. This is explained by the fact that, when nickel and cobalt are introduced into the cast iron, and an element from the group containing calcium, barium and strontium, with their 40

the ratio of 1: (O, 15-0.20) contributes to the alignment of the microstructure and properties of cast iron in thin and thick sections with a general increase in its strength properties .45

The optimum content of calcium, barium and strontium in cast iron should be in the range of 0.01-0.08%. If the content of these elements is less than 50

0.01%, there is no noticeable effect on the microstructure and properties

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1602880

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cast iron. The resulting graphite is in the form of long plastids and located in the type of rosettes, which reduces the strength properties of cast iron. With an increase in the content of these elements, more than 0.06%, their positive effect on the noBbmie properties of cast iron decreases and becomes uneconomical. 10 Iron forms the basis of cast iron.

The study of the properties of the prototype cast iron and the cast iron of the proposed composition was carried out on experimental castings.

The chemical composition and properties of the cast irons are given in Tables 1 and 2.

As follows from the data of table 2, additional input into the composition of the proposed cast iron Ti, Co, as well as in the form of Ba and Sr, making it possible to increase; strength limit 20 be, 1.16-1.27 times; HB in, 1.13-1.31 times, impact-fatigue strength in 1.21-1.34.

Claims (1)

Invention Formula Cast iron containing carbon, silicon, manganese, aluminum, copper, chromium, vanadium, nickel, nitrogen, an element from the calcium-containing group, and iron, differing from that. that, in order to improve the mechanical properties, it additionally contains titanium, cobalt, and the group additionally contains barium and strontium in the following ratio, wt.%: Carbon Silicon Manganese Aluminum Copper - Chrome Vanadium Nickel Nitrogen Titanium Cobalt One item from Calcium Barium and strontium 0.01-0.08 IronErest five 3.1-3.6 I, 5-2.6 0.6-1, 0.01-0.2 0.05-0.8 0.02-0.45 0.005-0.15 0.05-0.3 0, OOY-0.045 0.01-0.2 0.008-0.06 Table I Property famous  Strength at stretching, MPa 202-212 Modulus of elasticity, .МPA.1130-1190 ten- Shock fatigue strength, MPa Hardness, MPa 99-103 1850-1870 11 .. „Zi ... 1.T1 .. 261-265 239-250236-248 249-258 243-251 1360-1400 1270-1310 1250-1290 1320-1360 1280-1320 I4Q-U8 128-135126-134 138-14D 132-138 2470-2600 2230-2300 2170-2200 2470-2520 2350-2400 TV 2 Cast Iron Compound Yd