SU1560608A1 - Cast iron - Google Patents

Abstract

The invention relates to a foundry, namely, to compositions of high carbon iron alloys, and can be used in the manufacture of engine liners obtained by the method of centrifugal casting. The purpose of the invention is to stabilize the hardness over the section of the liner blanks, with the exception of face chill. The proposed cast iron contains, wt%: carbon 3.1-3.5

silicon 1.8-2.5

manganese 0.5-0.9

chromium 0.2-0.5

nickel 0.15-0.5

copper 0.2-0.5

vanadium 0.05-0.2

titanium 0.03-0.1

phosphorus 0,2-0,6

REM 0.005-0.02

magnesium 0.005-0.02

bismuth 0.003-0.01

iron - the rest. The use of the proposed cast iron makes it possible to drastically reduce the difference in hardness on the outer and inner surfaces of the sleeves, to obtain more uniform dimensions of the inclusions of graphite and to exclude the end churning of the sleeves when centrifugally casting into metal molds. 2 tab.

Description

The invention relates to foundry production, namely to compositions of high carbon iron alloys, and can be used in the manufacture of blanks, engine sleeves obtained by the method of centrifugal casting, to which there are increased requirements for the quality and stability of the microstructure.

The aim of the invention is to stabilize the hardness over the cross section of the liner blanks and to exclude face chill.

With the centrifugal method of casting liner blanks into permanent metal molds, the limits of the content of basic and alloying materials are optimized.

items. The proposed cast iron contains carbon, silicon, manganese, chromium, nickel, copper, vanadium, titanium, phosphorus, rare-earth metals, magnesium, bismuth and iron in the following ratio of components, wt.%:

3.1-3.5

1.8-2.5

0.5-0.9

0.2-0.5

0.15-0.5

0.2-0.5

0.05-0.20

0.03-0.10

Carbon

Silicon

Manganese

Chromium

Nickel

Copper

Vanadium

Titanium

Phosphorus

Rare earth metal

Magnesium

0.2-0.6 0.005-0.02 0.005-0.02

SP

Od

Oh oh

about

00

Bismuth 0.003-0.0

IronErest

As experimental studies have shown, the concentration assays of carbon (3.1–3.5 wt.%) And silicon (1.8–2.5 wt.%) With effective graphitizing modification of rare-earth metals (0.005–0.02 May.% and with the optimal content of carbide stabilizing elements: manganese (0.5-0.9 wt.%), chromium (0.2-0.5 wt.% and vanadium (0.05-0.2 wt.%) provide uniformly distributed inclusions of graphitl Additional input of magnesium (0.005–0.02 mas.%) and bismuth (0.003–0.01 wt.%) sharply reduces structural heterogeneity in length, and most importantly the radial thickness of the sleeves. The graphite keys and the eutectic cell are crushed. This significantly improves the distribution and structure of the phosphide eutectic. Combined with an increased cooling rate, adding magnesium, bismuth and rare earth metals allows for optimal antifriction structure of the sleeves at a phosphorus concentration of 0.2-0.6 wt. % and vanadium (0.05–0.2 wt.%), which also reduces the costs of doping. The mechanism of this effect from the additional input of magnesium and bismuth is associated with their strong influence on the process of crystallization of eutectic in cast iron. Magnesium in small amounts (up to 0.02 wt.%), By creating additional crystallization centers, removes supercooling. Bismuth in concentrations of 0.003-0.01 wt.%

increases hypothermia. Their joint input, especially in the presence of rare earth metals, allows not only to exclude edge chill, but also to grind the structure, to make it more homogeneous. Unlike calcium, the introduction of magnesium into liquid iron does not cause difficulties due to the significantly better solubility in it of magnesium than calcium.

The limits of the content of components are established experimentally. The lower limits for carbon (3.1 wt.%) And silicon (1.8 wt.%) Are limited by the possibility of chill formation, the upper (3.5 and 2.5 wt.%, Respectively) due to the ferritization of the alloy. The optimal structure of the metal matrix is provided by the following concentrations:

,

"

0

five

Qi, wt.%: manganese more than 0.5; chromium more than 0.2; Nickel 0.15; copper 0.2% and vanadium 0.05. Exceeding the upper limits for manganese, chromium and vanadium can lead to face bleaching with a centrifugal method of pouring sleeves. Above 0.5 wt.% Nickel and 0.5 wt.% Copper are not economically feasible, 0.2-0.6 wt.% Of phosphorus provides the required heterogeneous structure. Above 0.6 wt.% Of phosphorus can lead to segregation of phosphide inclusions during the centrifugal casting method, below 0.2 wt.% Of phosphorus impairs their wear resistance. Titanium in the range of 0.03-0.1 wt.% Contributes to the grinding of graphite inclusions.

Concentrations of rare-earth metals, magnesium and bismuth below the lower limits are not effective, more than 0.02 wt.% Rare-earth metals and 0.02 wt.% Magnesium can lead to an increase in the number of slag defects in the sleeves, more than 0.01 wt.% Bismuth causes a growth of chill. The combined effect of rare-earth metals, magnesium, and bismuth within the specified limits allows the creation of a large number of additional crystallization centers, and, due to the surface-active bismuth, significantly reduce the energy costs of eutectic nucleation.

Example. The test of three compositions of the proposed composition of cast iron at the lower, middle and upper limits of the content of components, as well as the known composition, selected as a prototype, was carried out during centrifugal casting of the billet outer with outer diameters and inner diameters of 100 and 60 mm, respectively, in metallic painted Lormy, Melting cast iron was carried out in an induction furnace with a capacity of 60 kg. Cast materials and pig iron, scrap steel, ferroalloys, silicon, manganese, chromium, vanadium, titanium were used as the charge materials. , phosphorus. Used granulated nickel, cathode copper. Treatment with magnesium and rare-earth metals was carried out in a ladle using a FSMg7 and FSZORMZO type ligature together with metallic bismuth. The values of additives were introduced with the calculation of the absorption of 85-95% of chromium, nickel, copper, 70-85% of vanadium, titanium, phosphorus, 60-70% of rare-earth metals and bismuth, as well as 45-55% of magnesium.

51

The chemical composition of the resulting BOB alloy is given in Table. one.

The resulting blanks were subjected to structural analysis, the hardness of the inner and outer surfaces, as well as the amount of face chisel of the outer angle bisector was measured. The data obtained are given in table. 2

When using the proposed composition of cast iron, the difference in hardness on the outer and inner surfaces of the sleeves is drastically reduced, more uniform dimensions of graphite inclusions are obtained, and mechanical chamfer of the sleeves is eliminated during centrifugal casting into metal molds.

Claims (1)

The invention of cast iron, mainly for blanks of engine liners obtained by the method of centrifugal casting, containing carbon, silicon, manganese, 60608 chromium, nickel, copper, vanadium, titanium, phosphorus, rare earth metals and iron, characterized in that, in order to stabilize the hardness of the liner billet section and eliminate face bleaching, it additionally contains magnesium and bismuth in the following ratio of components to 10, wt.%: 15 20 Composition jSi j Mn | Cr 1 Hi T C G V T Ti G R G RFM G MR G i T Iron - the basal Table 1 The content of components, wt.X Sa table 2