SU1421794A1 - Iron - Google Patents

Abstract

The invention relates to metallurgy and can be used in the manufacture of cast iron tooling. The purpose of the invention is to improve the mechanical properties, heat resistance and wear resistance. New cast iron contains, wt%: C 3.2-3.8} Si 1.5-2.5; Mp 0.2-0.7; Ni 0.2-0.4; Mo Oh, 1 - 0.7; V 0.02 - 0.2; A1 0.12 - 1.0; Or 0.03-0.33; Sn 0.02- 0, 1 2; - Niobium borides 0.02-0.27; titanium nitrides 0.05-0.25; C1 0.02-0.05; Mg 0.03-0.07; one element taken from the group containing Ba and Li 0.05-0.2; Fe rest. The addition of titanium nitrides, niobium borides, Ba or Li to the cast iron provides an increase in G in 1.13-1.23 times, C in, 25-1.36 times, S in 2.9-3.5 times, heat resistance 1.42-1.61 times and wear resistance. 1.32-1.52 times. .2 tab. w (/ s

Description

The invention relates to metallurgy, and in particular to the development of cast iron compositions for the manufacture of molds, molds, etc. ; The purpose of the invention is to improve the mechanical properties of wear resistance and heat resistance.

The choice of the frontier limits of the components of the In-cast iron proposed composition is due to the following. Additional introduction of niobium borides is due to the fact that they have the effect of inverting the structure, have a micro-effect, increase the stability of the structure under thermal shock conditions and its thermal stability, which provides a significant increase in the resistance of high-impact iron to thermal impact. With an increase in the concentration of niobium borides more than 0.27 wt.%, The number of crystal lattice defects of the metal base, non-metallic inclusions at grain boundaries increases, the shape factor of graphite inclusions worsens, thermal stresses increase, which reduces technological ductility, resistance to thermal shock . ,,

Vanadium is introduced as an effective microalloying - and, nitride-forming component, enhancing the effect of inverting the structure, substantially grinding the matrix and graphite inclusions, ensuring homogeneity of the structure and noBbmieHi-ie thermal stability and upproglastic properties and their stability. The upper limit of the vanadium concentration (0.2 wt.%) Is determined by a decrease in the technological plasticity of cast iron and an increase in the tendency to cracks at a higher content and the elongated elastic plastic properties after tempering.

Decreasing vanadium concentration

less than 0.02 wt.% decreases dynamic strength, yield strength and thermal resistance.

Additional introduction of titanium nitrides is due to their modifying effect, improving the morphology of the structure, increasing the elastoplastic properties, thermal stability, which contributes to an increase in the resistance of the pig iron to the heat of the titanium nitrides to 0.05 wt.% The modifying effect and the increase in the resistance of the thermal

Impacts are insufficient, and at concentrations of more than 0.25 wt.%, the number of nonmetallic inclusions increases, the elastoplastic properties and resistance to thermal shocks decrease.

The metal from the group containing barium and lithium increases the stability of the structure, contributes to the disintegration of eutectic cementite, cleans the grain boundaries, reduces the contamination of cast iron with nonmetallic inclusions, serves as surface-active additives, improves the uniformity of the structure, thermal stability and plastic properties. If their concentration is up to 0.05 wt.%, The modifying effect is insufficient, and if their content is higher than 0.2 wt.%, The heterogeneity of the structure increases, the technological plasticity, dynamic strength and thermal stability decrease.

The boundary parameters of carbon content (3.2–3.8 wt.%) And silicon (1.5–2.5 wt.%) Are determined based on the practice of producing high-strength cast irons with high elastic-plastic properties and high thermal stability. With a carbon concentration of over 3.8 wt.% And silicon over 2.5 wt.%, The endurance limit is reduced, the thermal resistance, toughness and other mechanical properties of cast iron, and with a carbon concentration of up to 3.2 wt.% And silicon to 1.5 wt.% Increase chill and thermal stress, crack resistance, thermal resistance, impact strength and other plastic properties in castings are reduced.

The content of alloying additives, wt.%:. Manganese 0.2-0.7; molybdenum 0.1-0.7; nickel 0.4-1.2; aluminum 0.12-1.0 is due to the substantial increase in thermal stability, technological plasticity and strength, and is limited to the limits below which the technological plasticity and strength properties are insufficient, and those that increase in terms. Com pany stress and reduced plastic properties, thermal resistance and the limit of endurance during bending.

The introduction of cerium in the amount of 0.02-0.05 wt.%: Tin 0.02-0.12 wt.% And magnesium 0.03-0.07 wt.% Due to

their high modifying efficiency and surface activity, which in these quantities provide purification of grain boundaries, increase of plastic properties, crack resistance and technological plasticity. Their content is due to the limits that ensure the production of a dispersed and homogeneous structure in castings, spherical graphite in cast iron and the required mechanical properties as well as a stable pearlite structure after heat treatment and the process of operation.

Melting iron is carried out in induction furnaces using cast iron, semi-finished nickel, iron and steel scrap, and niobium borides and titanium nitrides of ferroalloys as charge materials. The microalloying of the cast iron on briquettes of niobium borides, ferrovanadium FDd2, ferromolybdenum and silicomanganese CM-17 is carried out in an electric furnace at the end of smelting at a temperature G500-1520 C, and the modification is performed by ferrocerium, titanium nitride, barium, lithium, alloys magnesium and microalloying of cast iron with tin and aluminum - directly in distributing casting ladles with a capacity of 2 tons. The digestion of microfolding and modifying components is,%: vanadium from ferrovanadium VD2 88-92; barium 84-88; lithium aluminum-lithium alloys 83-86; niobium borides of extruded briquettes 91-94; titanium nitrides 81-84; cerium from ferroceri 75-78 and magnesium from its alloys 48-51.

Graded process samples are poured to determine the whitening. Copper in castings increases liquation, decreases structure stability, thermal stability, technological plasticity and elastoplastic properties, therefore it is excluded from

0 5

0 5 o 5

0

five

composition of the proposed high-strength cast iron.

Table 1 shows the chemical composition of the known and proposed cast irons; in tab. 2 - their properties.

The addition of niobium borides, titanium nitrides, as well as one element taken from the group containing barium and lithium, to the composition of the iron provides for an increase in mechanical properties; Gf 1.13g, 1.23 times; G y in - 1.25-1.36 times; S 2.9-3.5 times; heat resistance 1.42-1.61 times and wear resistance 1.32-1.52 times.

Claims (1)

Invention Formula Cast iron containing carbon, silicon, manganese, nickel, molybdenum, vanadium, aluminum, chromium, tin, cerium, magnesium, and iron, characterized in that, in order to improve the mechanical properties, heat resistance and wear resistance, it additionally contains titanium nitrides, niobium brides and one element taken from the group containing barium and lithium, with a ratio of components, wt%: Carbon 3.2-3-3.8 Silicon1.5-2.5 Manganese 0.2-0.7 Nickel0.4-1.2 Molybdenum 0.1-0.7 Vanadium 0.02-0.2 Aluminum 0.12-1.0 Chromium 0.03-0.33 Tin0.02-0.12 Cerium 0.02-0.05 Magnesium 0.03-0.07 Titanium nitride 0.05-0.25 Niobium borides 0.02-0.27 One element taken from the group containing barium and lithium 0.05-0.20 Iron Else. table 2 Temporary resistance Technological plasticity,% Wear resistance MG / M FC, with temperature C: 600 800 Relative wear resistance Resistance to thermal shock when heated to temperature, cycles: 600 800 Bending endurance limit, MPa 592,615,572,606,625 7.5 6.4 7.1 7.8 7.3 1912 1870 1786 1975 1817 168 175 155 172 178 4420 4731 3655 4532 4870 2980 3517 2176 3008 3312 436 460 405 441 475