SU1691419A1 - Cast iron - Google Patents

Abstract

The invention relates to foundry and can be used in mechanical engineering. The purpose of the invention is to stabilize the hardness over the cross section of castings and to improve their workability. The composition of cast iron, intended for the manufacture of cylinder liners, contains, wt%: carbon 2.9-3.3; silicon 1.5-2; manganese 0.85-1.25; chromium 0.4-0.6; nickel 1.1-1.5; molybdenum 0.4-0.6; copper 0.25-0.45: titanium 0.01-0.15; vanadium 0.001-0.05; calcium 0.005-0.05; barium 0.005-0.05; rare earth metals 0.001-0.01: nitrogen 0.005-0.01; zirconium 0.01-0.03; Selena 0.005-0.01; iron else. The additional introduction of Zr and Ce into the cast iron of the proposed composition allows stabilizing the hardness over the cross section of the casting and improving their workability. 2 tab.

Description

The invention relates to metallurgy, in particular, to the development of cast iron compositions used for the manufacture of critical castings, such as cylinder liners, sleeves and other wear-resistant parts.

The purpose of the invention is to stabilize the TV, to reach the cross section of the castings and to improve their workability.

The choice of the boundary limits of the content of components in the pig iron of the proposed composition is due to the following.

Additional introduction to the composition of zirconium iron in an amount of 0.01 - 0.03% contributes to the grinding of graphite inclusions and obtaining a homogeneous pearlite structure. The effect of zirconium is especially effective when co-introduced with modifier elements (rare earth metals, calcium and barium). With the input of less than 0.01% zirconium cast iron with a lower content in

The composition of calcium and barium 0.005% and rare earth metals 0.001% of its effect on the grinding of graphite inclusions does not manifest itself. Input of more than 0.03% of zirconium in the presence of strong carbide-forming elements, such as REM (0.01%), in the composition at the upper limit. chromium (0.6%). manganese f1.25%), vanadium (0.05%), leads to the formation of individual hardly soluble inclusions of cementite, which causes heterogeneity of the iron structure. Grinding graphite inclusions in the cast iron structure and obtaining a uniform pearlitic structure along the casting length contributes to obtaining a durable, high-quality chromic coating.

Entering selenium into the composition of cast iron in the amount of 0.005-0.01% together with calcium and barium contributes to obtaining a uniform structure of cast iron, eliminating the formation of primary inclusions of cementite, which has a favorable effect on oolong

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machinability of cylinder liners.

When selenium is introduced into cast iron in the presence of active elements such as calcium and rare earth metals, inclusions of a globular form, such as oxyselenides, are formed, which are the source of a protective film on the cutting edge of the processing tool that acts as a dry lubricant. When the content in the composition is less than 0.005% selenium and the lower limit of calcium 0.005% and rare-earth metals 0.001%, its effect on obtaining a homogeneous structure with the formation of a round form of hydroxelenides does not appear. Entering more than 0.01% of selenium is accompanied by the appearance of large graphite inclusions, which leads to a deterioration in the adhesion of the chromic coating to the cast iron matrix.

The presence of modifying elements - calcium, barium, rare-earth metals and nitrogen - together with zirconium and selenium additives helps to obtain a fine-grained structure along the entire length of the casting, grinding graphite. When the content of the composition is less than 0.005% calcium, less than 0.005% barium, less than 0.001% REM and less than 0.005% nitrogen, their action as modifier elements is ineffective. Entering more than 0.05% calcium, more than 0.05% barium, more than 0.01% REM, and more than 0.01% nitrogen with the upper content of carbide-forming elements (manganese, chromium, vanadium, zirconium) causes the formation of individual inclusions in the cast iron structure carbides, contributing to a heterogeneous pearlitic structure along the length of the casting.

Entering into the composition of alloying elements (manganese, chromium, nickel, molybdenum, copper, titanium, vanadium) contributes to an increase in the strength characteristics of cast iron and to obtain a pearlite structure. If the composition contains less than 0.4% chromium, less than 1.1% nickel, less than 0.4% molybdenum, less than 0.25% copper, less than 0.01% titanium, less than 0.001% vanadium with an upper content of graphitizing elements (carbon , silicon, calcium) significant portions of ferrite appear in the composition of the cast iron structure. Enter into the composition of more than 1.25% manganese, more than 0.6% chromium, more than 1.5% nickel, more than 0.6% molybdenum, more than 0.45% copper, more than 0.15% titanium, more than 0.05% vanadium contributes to obtaining chill casting.

The presence in the composition of an insignificant amount of carbon (2.9 - 3.3%) and silicon (1.5 - 2%) as graphitizing elements helps to obtain a pearlite structure without inclusions of cementite.

In tab. 1 shows the composition of cast iron. The required composition of cast iron receive. by melting in the induction furnace the original cast iron containing carbon, silicon, manganese, chromium, titanium, vanadium, nickel, followed by the introduction of the rare-earth FSGSMZZO alloy (containing 30% REM) into it, silicocalcium SC25 (with 25% calcium), Silikobari 0 SB15 (with a barium content of 14.5%) and an additional input into the ladle to optimize the composition of cast iron the required amount of selenium in the form of iron-settlement alloys (TU6-01-25-10-77) and alloying elements in the form of 5 ferroalloys (manganese, chromium , nickel, molybdenum, copper, titanium, vanadium, zirconium ). Then, purging of smelted iron with nitrogen is carried out in the ladle.

Treated samples are cast from the prepared composition of cast iron for testing and cylinder liners with a length of 1000 mm and a diameter of 220 mm. Chromium coatings are electroplated on the inner surfaces of the cylinder liners. Samples are cut out of the sleeves, their structure and the quality of the chromic coating are determined.

In tab. 2 shows the test results.

The mechanical properties of the proposed composition of cast iron, tested on samples cut from cylinder liners, are as follows: tensile strength of 340 - 390 MPa; hardness 220 - 240 HB.

As follows from the data table. 1 and 2, the additional input into the composition of the proposed zirconium and selenium iron allows to obtain a uniform hardness over the cross section of the castings and to improve their workability.

Claims (1)

Claims 0 Cast iron containing carbon, silicon, manganese, chromium, nickel, molybdenum, titanium, vanadium, calcium, barium, rare earth elements, nitrogen and iron, characterized in that. In order to stabilize the hardness over the cross section of die: wok and improve their workability, it additionally contains zirconium and selenium in the following ratio, wt.%: 0 Carbon 2.9 - 3.3 Silicon1.5-2 Manganese0.85-1.25 Chrome0.4 - 0.6 5Nickel1.1-1.5 Molybdenum0,4 - 0,6 Copper0.25 - 0.45 Titan0.01-0.15 Vanadium0.001-0.05 Calcium0.005 - 0.05 Barium0.005 - 0.05 Rare earth elements 0.001 -0.01 Nitrogen0.005 - 0.01 0.01-0.03 0,005-0,01 Rest Table 1 Proposed 1 2.9 2.00.85 0.6 1.1 0.1 0, - 45 0.01 Continued tlbl Cast iron / L-- -; The chemical composition of cast iron,% 1 - ee- -. в ™ вшш в ™ ™ interaction ™ «« ™ вв ™ ™ | ™ video in - i Ca J 2 -I Ј§ML N1-2L §ЈLis i 0,0050,050,0010,0050,010,01 0.0250.0250.0050.070.020.007 0,050,0050,010, 005 0,030,0250,0250,01 In the composition of the auth. No. 133659 additionally contains: cobalt 0.01; aluminum 0.02; tin 0.05; magnesium 0.05; antimony 0.05; ibop 0.01; sodium 0,005. 0.05 Continued tbl.1 ; Rest