RU2511226C2 - Method for obtaining pore-free carbide cast iron for manufacture of planishing machines - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy, and namely to production of carbide cast iron with no pores in alloy volume, and can be used for production of working parts of planishing machines. A method involves mixing of powders of titanium carbide and grey cast iron SCh20 in volume ratio of 50 : 50, pressing of the obtained mixture under pressure of 0.5 t, movement of the pressed part at a melting pot bottom and heating up to the temperature of 1250-1350°C in contact with a cast iron ingot, which is arranged on it and has the same grade as the powder, till it is fully molten; exposure at the same temperature with simultaneous saturation with titanium carbide, the particles of which rise to the surface in liquid cast iron as the ingot is being molten, and quick cooling.

EFFECT: method allows considerably simplifying a procedure for obtaining pore-free carbide cast iron.

1 ex, 2 tbl, 3 dwg

Description

The invention relates to metallurgy, and in particular to methods for producing wear-resistant composite materials, in particular to a method for producing carbide iron with no pores in the alloy volume.

It is known that carbide steels have a hardness that is comparable with the hardness of hard alloys (see Gurevich Yu.G., Antsiferov V.N., Savinykh L.M., Oglezneva S.A., Bulanov V.Ya. Wear-resistant composite materials. / Edited by Yu.G. Gurevich, Yekaterinburg: Ural Branch of the Russian Academy of Sciences, 2005 .-- 217 p.). However, these materials are obtained by powder metallurgy methods, the main disadvantage of which is that there are pores in the volume of the resulting product (over 2.0%), which makes it unsuitable for use in the manufacture of tools because the pores scratch the surface being treated and reduce the quality of processing.

A known method of producing carbide iron (see Pat. 2190681 Russian Federation, IPC C22C 1/04, C22C 29/10, C22C 33/02, B22F 3/12). A method of obtaining a wear-resistant composite material based on titanium carbide (Yu.G. Gurevich, P.V. Rothermel, L.M. Savinykh, I.M. Kovensky. - No.2000113923 / 01; decl. 31.05.2000; publ. 10.10. 2002), based on the sintering of a mixture previously compressed and dried in a vacuum oven containing powders of titanium carbide, cast iron and glycerin. The disadvantages of this method include the porosity of the sample, as well as the significant complexity and complexity of the technology associated with the need for powder preparation, preliminary impregnation and pressing of blanks (Gurevich Yu.G., Antsiferov V.N., Savinykh L.M., Oglezneva S. A., Bulanov V.Ya. Wear-resistant composite materials./ Edited by Yu.G. Gurevich.Yekaterinburg: Ural Branch of the Russian Academy of Sciences, 2005. - 217 p.).

Closest to the proposed is a method known to the applicant for producing carbide iron, comprising mixing powders of titanium carbide and cast iron and pressing the resulting mixture (RU 2190681 C2, C22C 1/04, 10/10/2002) / 1 /.

The technical result of the invention is to simplify the technology of producing non-porous cast iron for smoothers.

The proposed method differs from the known one from / 1 / in that powders of titanium carbide and gray cast iron are mixed in a volume ratio of 50% to 50%, the compressed mixture under a pressure of 0.5 tons is placed on the bottom of the crucible and heated to a temperature of 1250-1350 ° C in contact with the ingot placed on it, made of cast iron of the same brand as the powder, until it is completely melted, it is held at this temperature for 3-5 minutes and cooled in water.

An ingot of gray cast iron of the composition: 3.4% C; 2.2% Si; 0.6% Mn; <0.3% P and <0.3% S, hardness 140 HB of cylindrical shape with a diameter of 20 mm and a height of 50 mm and powder of titanium carbide (TiC) TU 6-09-492-75, composition wt.% 79,30 Ti , 18.78 C _total , 0.36 C _free , 1/7 O ₂ and cast iron powder of the same grade as the ingot.

Powders of titanium carbide and cast iron were mixed in ratios by volume of 50 to 50 and pressed at a pressure of 0.5 t, the compact (Fig. 1, pos. 3) was placed on the bottom of the crucible (Fig. 1, pos. 1), after which it Pig-iron shavings of the same grade were filled as cast-iron powder (Fig. 1, Pos. 2), and kept in an oven at a temperature of 1250-1350 ° C until the shavings were completely melted.

Metallographic analysis showed that when holding for 3-5 minutes, titanium carbide does not have time to float and remains in the volume of the alloy (figure 2). The hardness of the obtained cast iron was 58-62 HRC. The results of the experiment are shown in the table.

No. Heating up to 1250-1350 ° C and holding time, min A mixture of cast iron and titanium carbide,% The volume of carbide,% Hardness HRC 2 2-3 Warhead + 3-5% TiC 40-50 55-56 3 four Warhead + 10% TiC 70 56-60 four 5 Warhead + 10-12% TiC 70-80 60-62 5 6 Warhead + 3-5% TiC fifty 55-56

As follows from the table, carbide has a high hardness with a content of 70-80% titanium carbide in the mixture, but, as shown by experiments, with such a carbide content, the mixture has a large volume and carbides float very quickly, so the composition of the mixture was 50% carbide and 50% cast iron, and exposure time 5 minutes.

A smoothing agent was made from the obtained alloy (see Fig. 3). The experiments showed that the roughness of the surfaces treated with a smoother from carbide cast iron decreased on average 2-5 times compared with the original, which confirms the applicability of the method for the production of working parts of smoothers.

The proposed method of obtaining material for the manufacture of smoothers is simpler and cheaper than known methods, since it does not require:

- preparation of the initial powder to obtain the mixture;

- the use of glycerin and drying the powder mixture:

- allows to obtain a non-porous alloy structure.

An example of the method for producing non-porous carbide for tool composite material (smoothing agent)

1. Powders of gray cast iron and titanium carbide (TiC) with a particle size of ≤6.2 μm were mixed in a drunk barrel mill for 12 hours.

2. A mixture in a volume ratio of 40-80% TiC and 60-20% gray cast iron was pressed under a pressure of 0.5 tons, the compact was placed on the bottom of the crucible, after which cast iron shavings of the same grade were poured onto it.

3. The crucible was placed in a furnace with a graphite heater, heated to a temperature of 1250–1350 ° C, and after the melts were completely melted, they were kept at this temperature for 3-5 minutes and cooled in water. The table shows the hardness and composition of the obtained alloy.

No. Heating up to 1250-1350 ° C and holding time, min A mixture of cast iron and titanium carbide,% The volume of carbide,% Hardness HRC 2 2-3 Warhead + 3-5% TiC 40-50 55-56 3 four Warhead + 10% TiC 70 56-60 four 5 Warhead + 10-12% TiC 70-80 60-62 5 6 Warhead + 3-5% TiC fifty 55-56

As follows from the table, carbide has a high hardness with a content of 70-80% titanium carbide in the mixture, but, as shown by experiments, with such a carbide content, the mixture has a large volume and carbides float very quickly, so the composition of the mixture was 50% carbide and 50% cast iron, and holding time 3-5 minutes.

Claims (1)

A method of producing non-porous carbide iron for the manufacture of smoothers, characterized in that powders of titanium carbide and gray cast iron SCh20, containing, wt.%: 3.6 carbon, 2.2 silicon, 0.7 manganese, 0.12 sulfur, 0.15 phosphorus , to exclude pores in the material, they are mixed in a volume ratio of 50 to 50 and pressed under a pressure of 0.5 t, the pressed mixture is placed on the bottom of the crucible and heated to a temperature of 1250-1350 ° C in contact with a cast iron ingot of the same grade placed on it and the powder, until it is completely melted, is held at this temperature in t 3-5 minutes and cool in water.

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