SU872560A1 - Method of modifying ferrocarbon alloys - Google Patents

Description

The invention relates to the metallurgy of ferrous metals and can be used to produce modified cast iron. _

Various methods for introducing ⁵ Nia boron alloy. With the method of welding boron (Ferroboron) into the metal part of the charge, for example cupola melting, as well as with the method of laying ferroboron on the outlet chute of the melting unit, the digestibility of the modifier by the alloy is 30-40%.

When boron is introduced into a liquid alloy by immersion of a refractory 15 bell with a ferroboron placed in it, the degree of boron assimilation by the alloy is higher and reaches 70%, however, with this method, the loss of expensive metal is high [1]. 20

Closest to the proposed technical essence and the achieved effect is a method of producing an aluminum-boron alloy by introducing boron into an aluminum melt; at 25 cd, boron is introduced under a metal mirror in the form of a pre-sealed, powdery mixture containing boron, aluminum and graphite in the ratio components 1: .1: 2 [2]. 30 'However, this method is unacceptable for the modification of iron-carbon alloys, in particular cast iron, since the aluminum that is part of the mixture, remaining in the alloy, is in many cases undesirable since it worsens the properties of the metal. The degree of absorption of boron is low.

The aim of the invention is to increase the degree of assimilation of boron.

• The goal is achieved by the fact that according to the method of alloy modification, which includes introducing into the molten metal a pre-sealed powder mixture containing boron and graphite, a mixture containing boron, silicon and graphite is introduced into the metal at a ratio of '(0.81.2): (1.8-2.3): (0.7-1.2).

When ferrosilicon particles dissolve, they create volumetric contact with boron, the oxygen dissolved in the alloy is taken away, and their gardens are improved by their alloy retention: graphite creates a reducing atmosphere.

The degree of assimilation of boron, depending on the ratio of input components, is as follows:

B: Si: Tp = 0.8: 1.8: 0.7 88%

B: Si: Gy = 0.8: 1.8: 1.2 89%

87'2560

B: S ί: Γρ = 0.8: 2.3: 0.7 B: Si: rp = 1.2: 1.8: 0.7

B: Si: Gr = 1.2-: 2.3: 0.7 V: S i: Gr = 1.2: 1.8: 1.2

90%

89%

93%

91% of the mixture in the alloy of silicon and carbon is taken into account when preparing the mixture for smelting the alloy.

The proposed method is used in the smelting of cast iron for casting parts of brake pads, cylinder shirts, blades of shot blasting machines. The use of cast iron modified with boron increased the wear resistance of cast parts by 30-50%.

Example. The chemical composition of cast iron for casting parts such as brake. Blocks for working in a pair of dry friction with steel is the following,%: C - 2.8-3.2; Si 0.8-1.2; MP 0.5-0.8; P to 0.4, $ to 0.12; B 0.01-0.03; Fe the rest.

The chemical composition of cast iron for casting blades of shot blasting machines clean 1X ¹ kAmer is as follows,%: C 2.2-2.8; Si 0.8-1.2, - Mn 0.5-0.7; N1 1; 0-1.5;

) Cr 5.0-7.0, - B 0.05-0, 08; Fe the rest. Cast iron of the given composition for casting parts such as brake pads alloyed with boron is obtained as follows.

The molten cast iron melted in a cupola with a temperature of 1350-1380 ° C is discharged into a tonne casting ladle, into which a pre-prepared, crushed and mixed mixture containing per kg of metal 5.0 kg 5 is immersed in a metal box with small holes % ferroboron, 0.4 kg of 75% ferrosilicon, 0.25 kg of graphite. Mix the metal with a bar for 35 minutes, after which the metal is ready to be poured into molds.

Using the proposed method for modifying iron-carbon melts provides the following advantages compared to the known ones: a high degree of assimilation by an iron-carbon boron alloy, and also the ability to increase the wear resistance of parts by 30-50%.

The economic effect will be more than 100 thousand rubles. in year.

Claims (2)

The invention relates to the metallurgy of ferrous metals and can be used to produce modified cast iron. Various methods are known for introducing boron into the alloy. With the method of welding boron (Ferroboron) into the composition of the metal part of the charge, for example, cupola smelting, as well as with the method of laying the ferroboron on the outlet trough of the melting unit, the modifier's absorbability by the alloy is 30–40% When boron is introduced into the liquid alloy using refractory bell with a fan placed in it, the degree of absorption of boron alloy vpaye and reaches 70%, however, and with this method, the loss of expensive metal is great 1. The closest to the proposed technical essence and the achieved effect This is a method for producing an aluminum-boron ligature by introducing boron into an aluminum melt in which boron is introduced under the metal mirror as a pre-capped powdered mixture containing boron, aluminum and graphite with a ratio of 1: 1: 2 2. However, this method is unacceptable for modifying iron-carbon alloys, in particular cast iron, since the aluminum included in the mixture, remaining in the alloy, is in many cases undesirable because it affects the properties of the metal. The degree of assimilation of boron is low. The aim of the invention is to increase the boron uptake rate. The goal is achieved by the method of modifying alloys, which includes introducing a pre-corked powder mixture containing boron and graphite into the molten metal and introducing boron, silicon and graphite containing metal into the metal (0.81, 2): a, 8-2.3}: (0.7-1.2). The particles of ferrosilicon, dissolved, create a volumetric contact with boron, select oxygen dissolved in the alloy, and thus improve its gain in the alloy: graphite creates a reducing atmosphere. The degree of boron assimilation depending on the ratio of input components is as follows: 0.8: 1.8: 0.7 88% B: Si: Gr 0.8: 1.8: 1.2 89% B: 51: Gr 0, 8: 2.3: 0.790% B: Si: rp 1.2: 1.8: 0.789% B: S4: Gy 1.2-: 2.3: 0.793% 1.2: 1.8: 1.291% Introduced into cocfaB mixtures in silicon and carbon alloy is taken into account when preparing the charge for melting the alloy. The proposed method has been applied in the production of cast iron for casting parts for brake pads, cylinder jackets for shot blast blades. The use of boron-modified iron made it possible to increase the wear resistance of cast parts by 30–50%. Example. The chemical composition of cast iron for casting brake-shoe-type parts for working in a pair of dry friction with steel is as follows,%: C - 2.8-3.2; Si 0.8-1.2; Mp 0.5-0.8 P to 0.4, S to 0.12; B 0.01-0.03; Fe rest. The chemical composition of cast iron for casting blades of shot-blasting machines for cleaning the following amounts,%: C 2.2-2 Si 0.8-1.2; Mp 0.5-0.7; Ni 1; 0-1,5; ) Cr 5.0-7.0; B 0.05-6.08; Fe is the rest. Cast iron of a given composition for boring doped parts such as boron doped parts is obtained in the following way. Liquid chu gong smelted in a cupola with a temperature of 1350-1380 C is released into a ton pouring ladle, into which a pre-prepared, crushed and mixed mixture containing 5 tons of metal per ton of metal packed into a small box with small holes is immersed on a rod. 0 kg of 5% ferroboron, 0.4 kg of 75% ferrosilicon, 0.25 kg of graphite. The metal is stirred by a rod for 35 minutes, after which the metal is ready for pouring into the molds. Using the proposed method of modifying iron-carbon melts provides the following advantages compared with the known ones: a high degree of assimilation by the iron-carbon boron alloy, as well as the possibility to increase the wear resistance of parts by 30-50%. The ecological effect will be more than 100 thousand rubles. in year. DETAILED DESCRIPTION OF THE INVENTION A method for modifying iron-carbon alloys, comprising introducing into the molten metal a pre-closed powdered mixture containing boron and graphite, characterized in that, in order to increase the absorption of boron, a mixture containing boron, silicon and graphite is introduced into the metal ( O, 8-1,2: (1,8-2,3):: (0,7-1,2). Sources of information taken into account during the examination 1. Girshovich Iron casting. M., Mashgiz, 1977 , p. 37. 2. USSR author's certificate number 463733, cl. C 22 C 21/00, 1973.