SU1528795A1 - Method of producing grey iron - Google Patents

Abstract

The invention relates to foundry, in particular to the production of gray cast iron with a lamellar form of graphite for responsible automotive casting, for example castings of sleeves of ICE cylinders obtained by centrifugal casting. The purpose of the invention is to reduce the melting time and increase the hardness of the casting after quenching by high frequency currents. This is achieved by the fact that the cast iron is alloyed with the complex ligature NI-CU-FE with an FE / NI ratio of 4.47 - 4.84, copper in an amount of 0.1 - 0.6% by weight of the liquid iron, followed by modifying the melt 75% by FESI. An intermediate modification of 0.5-0.6% CU with an FE / NI ratio of 4.62 is optimal. The method allows to obtain a difference in hardness over a cross section of 18 to 20 units. HB, hardness after quenching HDTV 43 units. HRC and shorten the melting time to 140 min. 1 tab.

Description

The invention relates to foundry, in particular to the production of gray cast iron with a lamellar form of graphite for responsible automotive casting, for example, castings of cylinder liners two, obtained by centrifugal casting.

The purpose of the invention is to reduce the melting time and increase the hardness of the casting after quenching by high frequency currents. This goal is achieved by the fact that in the method involving the alloying of pig iron with a nickel-copper-chromium-silicon-manganese-iron-based titanium alloy and modifying the melt with ferrosilicon 75% is additionally introduced in an amount of 0.1-0.6 by weight of liquid iron, then the modification is carried out, and in the complex ligature the ratio between iron and nickel is -k, & k.

Under the action of centrifugal forces yi electrode, silicon, alloying elements are unevenly distributed over the cross section of the casting, unevenly distributed, and graphite-forming nuclei that have a major effect on graphitization. Copper as an element that has a grid of a face-centered cube contributes to graphitization, which is the strengthening of the bond copper-iron and diffusion graphitization. With the introduction of copper less than 0.1% of the properties of cast iron is reduced, and. entering more than 0.6% no longer raises them

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The introduction of copper makes it possible to prepare liquid iron for the final modification with a graphitizing modifier, for example, 75% ferrosilicon.

At a temperature of 1 80-1520 0, copper is introduced into the bottom of the lump of the lump, which dissolves well and promotes solidification of the iron according to a stable scheme.

A change in the ratio of iron to nickel in the complex ligature leads to an increase in the solubility of the ligature when interacting with the melt, accelerating its transition to the melt and reducing the melting time.

The combination of increased nickel content in the complex ligature and intermediate copper modification contributes to the alignment of graphitization throughout the cross section of the casting and increase in hardness, especially when quenching with high-frequency current (high-frequency currents).

Example. Were obtained gray cast iron by the known and proposed methods.

Melting in all variants of the methods was carried out in a crucible furnace IT-9 with a crucible capacity of 22.5 tons. Cast materials and pig iron, steel, scrap iron, ferroalloys, pure metals, master alloys were used as charge materials. The superheat temperature was 1500-320 ° C. The temperature at which the modification was carried out was 1460-1520 ° C.

The specified composition of cast iron, wt .: carbon 3.2-3.5; silicon 2, T-2,6; manganese 0.6-0.8; chrome 0 ,, “5; up to 0.2; Nickel 0.15-0.25; titanium 0.03-0.08; copper 0.3-0.6, Fe else

The order of filling is as follows: a return lump, a complex ligature, and then the rest charge materials were dumped on a bog 5 t. Copper was given in the form of pieces in a ladle.

; The time of iron smelting was recorded, which was determined from the moment the furnace was turned on with full filling up to iron production. The smelted cast iron entered directly into the channel mixer with a capacity of 2.5 tons and in portions in a carousel for casting sleeves. The cast iron was modified with ferrosilicon 75-FS75L with a fraction size of 1-3 mm.

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Spent liners were quenched with HDTV, after which hardness was determined on the hardened surface. Data on the amount of copper injected, the ratio of iron to nickel in the complex ligature, the composition and amount of ligature introduced into the metal mill, the difference in hardness over the cross section of the casting, the hardness of the sleeves after quenching with HDTV, the melting time are entered in the table.

From the data in the table, it follows that the application of the proposed method for producing gray iron can reduce the melting time by 12.5, reduce the difference in hardness over the cross section of the centrifugal casting by 3.

From the data of the table it follows that the optimal is the intermediate modification of 0.5-0.6% of copper with the ratio of iron to nickel in the complex master alloy 4, 47-,.

The use of this method also makes it possible to dispose of waste, reduce the cost of castings, reduce scrap in annular cracks and shrinkage porosity, and improve processing.

The resulting properties of cast iron are the following: the difference in hardness over the cross section is 20-18 units, hardness, hardness after quenching with HDTV 43 units. HRC, the melting time is reduced to 0 minutes.

Claims (1)

Formula from the range The method of producing gray iron, which includes the introduction of complex master alloys containing iron, silicon, nickel, copper into the metal smelter, melting and overheating of the melt, modifying with 75% ferrosilicon, characterized in that in order to reduce the melting time and increase the hardness of the casting after quenching high frequency, copper is additionally introduced into the melt in an amount of 0.1-0.6% of its mass after overheating the melt and modifying it, while the ratio of iron to nickel in the complex master alloy is 4,47, 8. Famous; 1) doping with a ligature according to a.c, composition 928830, May: 5.1 Ni; , 55 Si; 2.6 1.2 Cj 5.5 Ci; 0.5 li; 0.3 Mn; 0.3 Co; 80 Fe 2) modification of 0.3 by weight of liquid iron with ferrosilicon 75 Proposed - I. 1) doping with a ligature, containing, May .: 15 N1; 2.0 Si; 1.7 Cr; 2.7С; 5.7 C; 0.9 MP; 0.4 P; 72.6 Fe in the amount of 2.6 by weight of the metal beater; 2) intermediate copper modification of 0.1 melt weight; 3) modification of 0.3 with ferrosilicon FS75 from the weight of the melt Proposed II. 1) doping with a ligature containing, us: IS, 2S Ni; 2.1 Si; t, 85 Cr 2; 75 C; 6.1 Cu; 1.0 Mn; 0.5 P; 70.45 Fe in the amount of 1 | B by weight metallozavalki 2) modification of 0.5 by weight of the melt (intermediate) 3) modification of 0.3 ferrosilicon FS75 by weight of the melt Proposed III. 1) alloying with a ligature containing, May .; 15.5 Ni, 2.2 Si; 20 Cr; 2.8С; 6.5 MF; 1.1 MP; 0.6 P; 69.3 Fe in the amount of 0.5 by weight 2) modification with copper in the amount of 0.6 by weight of the melt (intermediate) 3) modification of 0.3 ferrosilicon 75 by weight of the melt Beyond I. 1) ligature doping, containing 15.75 N1; 2.2 S1; 2.0 Cr; 2.8 С; 6.5 C; 1.1 MP; 0.6 P; 69.05 Fe in the amount of 1.85 by weight of metal hitch 2) modifying 0.7 copper by weight of liquid melt 3) modification of 0.3% ferrosilicon FS 75 by weight of the melt Beyond II. I) doping ligature containing, by weight. 1 (, 75 Ni; 2.0 Si; 1.7 Cr; 2.7 C; 5.7 Cu; 0.9 Mp; 0.4 R; 72.85 Ke in the amount of 1.85 by weight of metal dumping 2) intermediate modification of 0.05 copper by weight of the melt 3) modification of Q, J ferrosilicon 75 by weight of the melt Beyond III. O doping ligature containing, masD 11 |, 75 Ni; 2.0 Si; 1.7 Cr; 2.7 C; 5.7 C; 0.9 MP; 0.4 P; 72.5 Fe in the amount of 0.85 by weight metalworking 2) modifying 0.3 ferrosilicon 75 by weight of the melt 15.7 160 3038 t, uk 135 22kl "., 62 1l | 0 I, 1 (7I 18) 3 .38 150 20ki ChE 155 2l “liO ,9 156 2639 Compiled by E. Arkhipenkov Editor M.Nedoluzhenko Tehred L.Serdyukova Proofreader; N.Korol Order 7616/23 Circulation 530 VNIIPI of the State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 113035, Moscow, Zh-35, Raushsk nab., “/ 5 Subscription