SU1458418A1 - Malleable iron - Google Patents

Abstract

The invention relates to metallurgy and can be used in the production of ductile iron castings. The purpose of the invention is to increase the toughness and corrosion resistance. New cast iron contains, wt%: C 2.15-2.85; Si 1.1-1.6; MPO, 01-0.09; Cr 0.01-0.08; Cu 0.25-0.80; B 0.001- 0.007; Those 0.0003-0.0008; La 0.008 - 0.04; Nd 0.004-0.02; Pr 0,002-0,01; Er 0.0005-0.001; Fe - the rest. Before- . Complementary commissioning of B, Te, La, Nd, Pr and Er cast iron provided an increase in the toughness of cast iron by 1.5 times and corrosion resistance by 4 times, table 2.

Description

i

(L

The invention relates to metallurgy and can be used in the production of ductile iron with a high level of properties.

The purpose of the invention is to increase the toughness and corrosion resistance.

The invention is illustrated by examples of specific embodiments. The choice of the boundary limits of the content of the components included in the composition of the proposed iron, is determined as follows.

The lower limits of carbon (2.15 wt.%) And silicon (1.1 wt.%) Are the boundary, after which there is a significant decrease in the number of graphitization centers and the formation of an unfavorable primary structure of white iron, as well as a decrease in the fluidity of the melt. The upper limits of these elements (C 2.85 and 6 wt.%)

selected in view of preventing the formation of graphite inclusions during the initial crystallization of liquid iron and accelerating the formation process and increasing the inclusions of carbon annealing during the heat treatment process.

The lower limit (0.01 wt.%) Of manganese was chosen taking into account its minimum content in the blend materials. The manganese content above the upper limit (0.09 wt.%) Inhibits the graphitization stage, thereby contributing to the perlithization of the metal base, which leads to a reduction in the toughness of the iron.

The positive effect of chromium as an alloying element affects only the content of 0.01-0.08 wt.% On the size of the primary grains. When the chromium content is higher than the upper limit (0.08 wt.%), Despite the presence of modifying and graphitizing

4 SL 00 4

thirty

its carbon-forming action (the ductility and toughness of cast iron decrease, although the corrosion resistance somewhat increases.

The doping of cast iron with copper has a positive effect on the process of graphitization, reducing the cycle of graphitizing annealing, and at the same time increasing the strength. Bone properties and corrosion resistance due to the formation of hardening penetration solutions.

With simultaneous acceleration of the first stage of graphitizadium and copper, it is removed by the oxygen, sulfur and demodifying eutectoid transformations by elements.

sufficiently high degree of compactness of inclusions of graphite and neutralization of impurity elements, a negative effect on the properties of cast iron.

The modifying effect of the introduction of these elements into the melt within the indicated limits is manifested primarily in the fact that, due to the low solubility of lanthanum, neodymium, praseodymium and erbium in austenite, they are strongly segregated between the branches of dendrites and at the grain boundaries of the primary phases o the result of interacting with

by more than 10 ° C. The high copper content in the upper f y limit (0.8 wt.%) is directly related to the complex effect of the modifying elements, which are in the process of operation of the parts. of such cast iron gives them better corrosion resistance. The content above the upper limit leads to a decrease in viscosity and plasticity due to the presence of pearlite in the cast iron structure. Content less than the lower limit (0.25 wt.%) Does not affect the physical and mechanical properties of D

Boron addition in the range of 0.001 - 0.007 wt.% Leads to the formation of fine boron carbides with high melting point in liquid iron.

boron was introduced into the bucket,

tellurium, lanthanum, neodymium, praseodymium and erbium. Filling in a single form was carried out at 1420-5380 ° C. Liquid cast iron previously held

5 minutes.

days of the boundaries of the primary grains, slowing their growth, contributing to -, thereby the formation of a fine structure. Boron content is less than lower

The limit (0.001 wt.%) does not have a per-40. Cast samples were subjected to a graphitization-positive effect, and more than the upper runner-annealing on the ferritic structure according to the mode: heating and holding at the high-temperature stage at the 900d (0.007 wt.%) prevents graphitization at.

The addition of tellurium contributes to a sharp increase1; according to crystallization centers, while improving the compactness of graphite inclusions, the content of tellurium, less than the lower limit (0.0003 wt.%) Does not affect the structure of cast iron, and more than the upper limit (0.0008 wt.%) is its negative effect, in particular the formation of sinks, which creates significant technological difficulties.

Complex modification of lan-. i tan, neodymium, praseodymium and erbium leads to a significant reduction. the duration of the annealing cycle.

950 ° С.6 h, cooling in an oven to 45, then air cooling.

The chemical composition of the cast iron is given in table 1, and the strength characteristics in table 1 2.

The proposed composition of cast iron 50 compared with the prototype provided an adherence to impact strength in the temperature range of 20 - (-50 ° C) 1.5 times and corrosion resistance 4 times.

Claims (1)

55 claims Ductile iron containing carbon, silicon, manganese, chromium, copper and iron, distinguished by that. oxygen, sulfur and demodifying elements removes them sufficiently high degree of compactness of inclusions of graphite and neutralization of impurity elements, a negative effect on the properties of cast iron. The modifying effect of the introduction of these elements into the melt within the indicated limits is manifested primarily in the fact that, due to the low solubility of lanthanum, neodymium, praseodymium and erbium in austenite, they are strongly segregated between the branches of dendrites and at the grain boundaries of the primary phases o the result of interacting with from the melt, which effectively affects the graphitization and the structure of the metal base, and consequently, the strength properties of cast iron. The content of these elements (each separately) is less than the lower (La 0.008; Prg 0.002; Nd 0.004; Er 0.0005 wt.%) And the upper limits (La 0.04; Nd 0.02; Pr 0.01; Er 0.001 wt.%) Does not provide the required properties of ductile iron. P ROME Iron smelting was carried out in an induction furnace IST-025 on the charge, consisting of pig iron and steel scrap. Copper was injected into the melt, then it was overheated to, held for 10 minutes and released into the casting ladle. Before we leave the forms for the cast iron 5 minutes. 950 ° С.6 h, cooling in an oven to 45, then air cooling. The chemical composition of the cast iron is given in table 1, and the strength characteristics in table 1 2. The proposed composition of cast iron 50 compared with the prototype provided an adherence to impact strength in the temperature range of 20 - (-50 ° C) 1.5 times and corrosion resistance 4 times. 55 claims Ductile iron containing carbon, silicon, manganese, chromium, copper and iron, distinguished by that. that, in order to increase toughness and corrosion resistance, it additionally contains boron, tellurium, lanthanum, neodymium, laser | F1 and erbium in the following ratio of components, MaCoJf: Carbon2.15-2.85 Silicon1,1-1,6 Manganese 0.01-0.09 Iametyuy2,101,350,400,) 0 Presumptive 12, 10,010,01 22,501,350.0 & 0.04 32,851,60,090,08 Chromium Copper Boron Tellurium Lanthanum Neodymium Praseodymium Erbium Iron 0.01-0.08 0.25-0.80 0.001-0.007 0.0003-0,0008 0.008-0.04 0.004-0.02 0.002-0.01 0.0005-0.001 Else t el R c I 0.03 0.1 0.03 0.05 Ostalkvv 0.004 0.002 0.0005 - 0.008 0, B07 0.001 - 0.02 0.01 0.0008 Table 2