SU1357453A1 - High-strength cast iron - Google Patents

Abstract

The invention relates to metallurgy and can be used in the production of castings for agricultural machinery. The purpose of the invention is to increase the elastoplastic properties and torsion endurance limit. New cast iron contains, in May.%: C 3.2-3.8; Si 1.5-2.2; MP 0.2-0.5; A1 0.2-1.0; N 0.11-0.27; REM 0.03-0.08; V 0.12 - 0.28; Mg 0.03-0.07 and Fe - the rest. The addition of V and Mg to the composition of cast iron makes it possible to increase the endurance limit for torsion by 1.6-1.7 times, the relative elongation by 2.7-3.2 times and the impact strength by 1.6-2.3, times . 2 tab. S Nl O1

Description

The invention relates to metallurgy, in particular to the development of cast iron compositions.

The purpose of the invention is to increase the elastic properties and torsional endurance.

The selection of the boundary limits for the content of the components included in the composition of the proposed pig iron is carried out as follows.

The introduction of nitrogen is due to the fact that it forms, with silicon, manganese, vanadium, aluminum and carbon, nitrides and complex carbonitrides, which micro-alloy the metal base and alter the structure, which are crystallization centers, which contributes to an increase in toughness and elastic-plastic properties. The introduction of up to 0.11 wt.% Of nitrogen does not provide a sufficient number of crystallization centers in the melt during solidification in sandy-clay forms, a significant comminution of the structure in castings and an increase in the elastoplastic properties - with increasing nitrogen concentration more than 0.27 wt.% the number of defects in the crystal lattices of the metal base, non-metallic inclusions along the grain boundaries, the shape factor of the graphite inclusions deteriorates, the thermal stresses increase, which reduces the technological plasticity and endurance in torsion.

Vanadium is introduced as an effective microalloying and nitride-forming component, which substantially grinds the matrix and graphite inclusions, ensuring uniformity of the structure and enhancing the elastic-plastic properties and stability of torsion endurance. Upper concentration limit

Vanadium (0.28 wt.%) is caused by a decrease in the plastic properties, by the frustration of technological plasticity and by an increase in chill out at its higher content. When the vanadium concentration decreases to less than 0.12 wt.%, The structure is enlarged, the uniformity of graphite inclusions decreases, the dynamic strength, the yield strength in torsion, and the chilliness increases.

Rare-earth elements (REM) - cerium and neodymium or praseodymium - contribute to the disintegration of eutectic cementite, clean the grain boundaries, reduce the contamination of the iron non-metallic resistance and technological plasticity. Their content is due to the limits that provide nodular graphite in non-ferrous cast iron and the necessary mechanical properties.

The cast iron is produced by a duplex process (cupola - induction furnace) using as charge

gg materials foundry pig iron, steel scrap and ferroalloys. The microalloying of pig iron with ferrovanadium FVd2N, ligature VdA-2H and silico-manganese CM-17H is carried out in electric furnaces with conical inclusions, increase the torsional endurance strength, and elastic-plastic properties. When the concentration of neodymium or praseodymium is up to 0.01 wt.%, The modifying effect is insufficient, and with an increase in their content of more than 0.03 wt.%, The chill is increased, the technological plasticity and dynamic stability decrease.

The boundary parameters of carbon content (3.2–3.8 wt.%) And silicon (1.5–2.2 wt.%) Are determined based on the production of high-strength cast irons with enhanced elastoplastic properties and fine-grained structure. When the concentration of carbon is more than 3.8 wt.% And silicon is more than 2.2 wt.%, The endurance limit during torsion, impact viscosity and other mechanical properties of cast iron decrease, and at a carbon concentration up to 3.2 May, 7, and silicon to 1 , 5 wt.%, Chilling and thermal stresses increase, crack resistance decreases, impact toughness and torsion endurance limit.

The content of alloying additives (manganese 0.2-0.5 wt.%, Aluminum 0.2-1.0 wt.%) Is due to a significant increase in technological plasticity and strength and is limited by the limits below which technological plasticity and strength properties are insufficient, and higher which increase the thermal stresses and decrease the plastic properties and the limit of endurance during bending and torsion.

The introduction of magnesium (0.03-0.07 wt.%) Due to their high modifying efficiency and surface activity, which provide

stability and technological plasticity. Their content is due to the limits that provide nodular graphite in non-ferrous cast iron and the necessary mechanical properties.

The cast iron is produced by a duplex process (cupola - induction furnace) using as charge

gg materials foundry pig iron, steel scrap and ferroalloys. The microalloying of pig iron with ferrovanadium FVd2N, ligature WdA-2H and silico-manganese CM-17H is carried out in an electric furnace in horse-iron.

Claims (1)

Invention Formula 313574534 grades at 1420-1450 ° C, modified by 2.7-3.2 times and toughness in talent - by ferrocerium, by alloys 1.6-2.3 times as compared with lime-magnesium-praseodymium and magnesium-neodymium, and microalloying of cast iron with nitrogen and aluminum directly in the distribution, with precision casting buckets, 2 tons. Digestion of microalloying and micro- High-strength cast iron containing the constituent components of carbon, silicon, manganese, aluminum wt.%: Ferrovanadium Vd2Ni vanadium, nitrogen-, rare earth elements 88-94 {praseodymium and neodymium from fO and iron, characterized by magnesium-praseodymium and magnesium-neodymium in that, in order to increase the elasticity, 70-74; nitrogen from nitrided ferroplastic properties and the elimination limit of 78-84; cerium is from ferroceri torsional effusion, it has an additional 75-78; magnesium from its alloys 51-54. It contains vanadium and magnesium in order to determine the bleaching that is used to fill the f5 with the following ratio of components, foamy process samples. wt%; Table 1 shows the chemical compositions of the cast iron, and Table 2 shows the results of the analysis of the properties of the known and proposed cast iron. As follows from Table 2, the additional input of vanadium and magnesium into the composition of cast iron allows to increase the endurance limit During torsion by 1.6-1.7 25 times, the relative elongation by Cast iron T  - The amount of REM. - Cast iron, in addition, wt. Cr 1.1; Ti 0.15; Ca 0.06. Nym iron. 2.7-3.2 times 1.6-2.3 times Invention Formula 2.7-3.2 times and toughness 1.6-2.3 times as compared with lime Table 1 Component content, May.2 - 750 4.0 29 482 10.9 48 P2 171 540 12.2 65 193 558 11.6 62 188 Editor N.Rogulich Compiled by N.Kostornoy Tehred And, Popovich Proofreader G. Reshetnik 5971/24 Circulation 605 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035j Moscow, Zh-359 Raushsk nab., 4/5 . Production and printing company, Uzhgorod, Projecto st., 4 Table 2 ; 543 565 335 12.9 11.8 4.7 68 64 32 19B 191 125 519 9.8 44 161 480 10.2 42 163