RU2528687C1 - Production tillage tool working members - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: proposed method comprises forming of said members for hot-rolled bimetallic sheet and heat treatment. Main layer is made from alloy steel that contains the following components in wt %: carbon - 0.10-0.50; silicon - 0.5-1.5; manganese - 0.5-1.5; chromium - 0.5-1.5; phosphorus - not over 0.025; sulphur - not over 0.025, iron and unavoidable impurities making the rest. Clad layer is made from high-alloyed wearproof steel containing the following elements in wt %: carbon - 0.7-1.2; silicon - 0.1-1.7; manganese - 0.15-0.80; chromium - 0.6-2.0; molybdenum - to 0.3; phosphorus - not over 0.025; sulphur - not over 0.025, iron and unavoidable impurities making the rest. Clad layer is applied by ESR process on said base layer. prior to forming, said sheet is annealed at 680-820°C. Thermal treatment comprises quenching at 850-950°C at tempering at 150-250°C.

EFFECT: higher adhesion of layer and machinability, hardness and wear resistance.

4 cl, 6 tbl

Description

The invention relates to the field of agricultural engineering and can be used in the manufacture of working bodies of tillage machines, such as plowshares, dumps, field boards, counter plates, chisels, disks, cultivator paws and others.

The working bodies of tillage machines must have high wear resistance, strength and, in addition, the optimal shape of the cutting blade must be maintained during operation.

A known method of obtaining the working bodies of tillage machines, which consists in the fact that the billet of steel with a carbon content of 0.35-0.60% and manganese 0.2-0.8% is heated to 840-860 ° C and hardened to a hardness of 30- 40 HRC. Then lead electric arc surfacing wear-resistant alloy. After that, leave in an electric furnace at a temperature of 350-400 ° C to obtain a sorbitol-troostite structure of the base metal, which has optimal strength properties for the deposited working bodies operating under alternating loads.

(Patent RU 2010867, description, IPC C21D 1/00, published April 15, 1994)

The disadvantage of this method is to obtain a deposited wear-resistant layer with insufficient adhesion to the main part, which often leads to delamination of the deposited layer both during subsequent heat treatment and during operation of the part, as well as uneven wear of the deposited layer.

A known method of manufacturing plowshares, including the formation of a ploughshare by casting from steel with a carbon content of 0.8-1.4% and manganese 10-15%, its quenching with heating to a temperature of 1000-1050 ° C and cooling in water. When plowing the soil, the surface layer of the ploughshare, which undergoes abrasion and impact, is hardened due to the transformation of austenite into martensite, which is well resistant to abrasion, and as a result of hardening. The austenitic structure of the internal volume is characterized by high viscosity and successfully resists shock loads.

(Patent RU2207386, IPC C21D 9/18, published June 27, 2003)

The disadvantage of this method is that the conversion of austenite to martensite occurs at sufficiently high loads (impacts), comparable with the value of the elastic limit for this steel, which is practically unattainable in the process of cultivating the earth (plowing). Thus, with a fairly good viscosity, the surface layer, as a rule, has a relatively low hardness (of the order of 40-45 HRC), this leads to a fairly quick attrition of the part, and necessitates its replacement.

A known method of obtaining a working body of tillage machines, which has a body containing a surface layer and a core, and a working part in the form of a blade or tip. The method consists in the fact that the working body is made of carbon steel with reduced hardenability with a carbon content of from 0.40 to 0.80 wt.%, Subjected to volume-surface hardening with self-tempering or tempering in the furnace, while the surface layer of the body and the working part performed with the microstructure in the form of tempered martensite with the size of the actual austenite grain in the range of more than 11 points, but not more than 14 points and with a hardness of 55-60 HRC, and the core of the body is performed with the microstructure in the form of troostite or troostosorbite, or sorbitol with tv rdostyu 34-46 HRC. The technical result of the invention is improving the quality of the working bodies of tillage machines by increasing their wear resistance and impact resistance.

(Patent RU 2233570, description, IPC A01B 15/00, published August 10, 2004)

The disadvantage of this method is that the surface layer of the body and the working part of the original working body must be characterized by the microstructure of primary austenite with a grain size in the range of more than 11 points, but not more than 14 points. This condition is necessary to obtain hardness 55 - 60 HRC, and as a result of high wear resistance, however, the implementation, control and stability of this parameter are very difficult in the conditions of mass production of working bodies, and the consequence is its failure.

The closest analogue of the claimed invention is a method of manufacturing working bodies of tillage machines, including shaping and heat treatment of self-sharpening shares, retractable chisels, plane cutters, cultivator paws and other working bodies from bimetal produced according to GOST 15891-70. L53 steel is used as the basis of bimetal, X6F1 steel is used as a layer of increased hardness. The chemical composition of steel L53, wt.%: Carbon 0.47 - 0.57; manganese 0.5 to 0.8; silicon 0.15-0.35; sulfur ≤0.05; phosphorus ≤ 0.04; iron is the rest. X6F1 steel contains the following elements, wt.%: Carbon 1.40 - 1.70, manganese ≤0.5; silicon≤0.70; chrome 5.50 - 7.00; vanadium 0.80-1.20; sulfur ≤0.03; phosphorus ≤0.03.

The use of bimetals increases the service life and gives the blades of tillage machines made from these bimetals the ability to self-sharpen, as a result of which intermediate sharpening is not required until the product is completely worn out. (A.G. Kobelev, I.N. Potapov, E.V. Kuznetsov “Technology of layered metals” M. Metallurgy 1991, pp. 244 - 244 - prototype.)

The disadvantage of this method is the low adaptability of X6F1 steel in the production of bimetal, as well as in the process of manufacturing the working bodies of tillage machines, which consists in the occurrence of cracks when it is necessary to carry out bending and stamping operations, in addition, because of the insufficiently high adhesion strength of the layers in such bimetal, it is possible stratification during the manufacturing process of the product and during its operation.

The problem to which the invention is directed, is to obtain the working bodies of tillage machines with high strength, hardness and wear resistance, as well as the adhesion of the layers while maintaining the optimal shape of the cutting blade during operation.

The technical result of the invention is to increase the adhesion strength of the layers, increase manufacturability in the manufacture of products, obtaining high rates of strength, hardness and wear resistance of the finished product, as well as maintaining the optimal shape of the cutting blade during operation.

The specified technical result is achieved by the fact that in the method of manufacturing the working bodies of tillage machines, including the shaping of the working parts from a hot-rolled bimetal sheet and heat treatment, according to the invention, the main layer of bimetal is made of alloy steel, containing, wt.%:

carbon 0.10-0.50,

silicon 0.5-1.5,

manganese 0.5-1.5,

chrome 0.5 - 1.5,

phosphorus no more than 0,025,

sulfur no more than 0,025,

iron and unavoidable impurities - the rest,

The cladding layer is made of highly alloyed wear-resistant steel, containing, wt.%:

carbon 0.7-1.2,

silicon 0.1-1.7,

manganese 0.15-0.80,

chrome 0.6 - 2.0,

molybdenum to 0.3,

phosphorus no more than 0,025,

sulfur no more than 0,025,

iron and unavoidable impurities - the rest,

and applied to the main layer by electroslag surfacing, before forming, the sheet is annealed at a temperature of 680-820 ° C, and heat treatment is carried out by quenching from a temperature of 850-950 ° C and tempering at a temperature of 150-250 ° C. The steel of the cladding layer may further comprise, wt%: tungsten 0.02-1.0 and vanadium 0.02-0.2. The shaping of field boards, counter plates, discs, plow bits includes cutting blanks from a sheet and machining. The shaping of plowshares, paws includes cutting blanks from a sheet, machining, hot bending, providing the desired shape.

The invention consists in the following.

The use of the specified composition with a limited sulfur and phosphorus content as the main layer of bimetallic alloy steel sheets of this composition helps to ensure high strength and toughness indices necessary to ensure a high service life of wear-resistant bimetallic material subjected to shock loads.

The cladding layer of bimetallic sheets made of high alloy steel of the claimed composition provides a high level of wear resistance. The application of the cladding layer on the main layer by electroslag surfacing provides high adhesion layers.

A prerequisite for obtaining high processability in the manufacture of products is to ensure low hardness of the sheets before manufacturing. Low hardness of rolled products before forming products is achieved by annealing bimetallic hot-rolled sheets at a temperature of 680-820 ° C. As a result of exposure at these temperatures, on the one hand, martensite is tempered, which reduces hardness, on the other hand, solid carbide particles are formed, including chromium and vanadium, which cause additional (plus hardening by the formation of martensite during quenching) hardening of the finished products.

The high hardness of the finished product after hardening and low-temperature tempering is an indicator of its wear resistance.

Studies of the effect of quenching and tempering temperatures have revealed the following patterns of structure formation, including the nanostructural component, as well as the properties of the steels of the investigated chemical composition during the heat treatment of two-layer rolled products and finished products. In steels additionally alloyed with chromium, as well as, in particular cases, vanadium and tungsten, nanostructuring occurs during the annealing process - the release of nanosized particles of chromium, tungsten and vanadium, to a much greater extent than in steels alloyed with silicon. These particles can be stored in steel during heating under quenching and cause additional (in addition to hardening due to the formation of martensite) hardening of steel by the dispersion hardening mechanism. In addition, such particles can inhibit the growth of austenitic grain during heating under quenching and thereby lead to the formation of even finer dispersed martensite. That is, the formation of a cladding layer in steel during annealing of nanosized particles of chromium, tungsten and vanadium carbides is a method of obtaining both a nanostructured and nanostructured cladding layer of bimetal, which increases its hardness, strength and wear resistance. At the same time, the highest hardness of such steels is ensured after tempering at a temperature of 150 ° C. For steel alloyed only with chromium, a decrease in hardness is observed at a tempering temperature above 250 ° C, for steels alloyed additionally with vanadium and tungsten, an increase in tempering temperature to 200 ° C and above leads to a decrease in hardness to values below 60 HRC, which is related to with the release of martensite, and with the enlargement of particles of excess phases.

For steel alloyed with chromium, as well as, in particular cases, vanadium and tungsten, the precipitation of nanosized carbide particles during annealing occurs to a much lesser extent, which is associated with a high silicon content in the steel, which inhibits diffusion processes. When heated for quenching, a large austenite grain is formed, with subsequent cooling, martensite with a large needle size is formed, especially after quenching from 950 ° C. Moreover, the number of particles of excess phases in the steel is small. At the same time, an increase in tempering temperature to 200–250 ° C leads to the precipitation of substantially finer carbide particles, which cause precipitation hardening and lead to a significant increase in hardness, despite martensite tempering.

A further increase in tempering temperature to 300 ° C leads to a certain decrease in hardness, however, for all tempering temperatures of at least 200 ° C, the hardness values are maximum precisely for the cladding layer of steel, additionally alloyed with chromium, vanadium and tungsten.

Thus, the temperature range of quenching is 850-950 ° C, tempering is 150-250 ° C.

Examples of the invention.

Bimetallic billets with a main alloy steel layer (steel composition are given in Table 1) and a deposited high-carbon steel layer with increased wear resistance (steel composition is shown in Table 2) with a deposited layer thickness of 30-80 mm were obtained by electroslag surfacing. The billets were heated for hot rolling to temperatures of 1150–1250 ° C and rolled onto 10 mm thick sheets.

Ultrasonic testing of sheets was carried out to check the continuity of the connection of the layers in accordance with the requirements of GOST 22727 "Sheet metal. Methods of ultrasonic testing. " The continuity of the connection of layers on all sheets corresponded to 0-1 classes, which is an indicator of high quality.

Then, the resulting roll was cut into measuring sheets and subsequent annealing was carried out (the annealing parameters are shown in Table 3) to reduce the hardness of the clad layer and increase its manufacturability when receiving products. The sheet of option 5 with the main and cladding layer is the same as for option 4, not annealed. The mechanical properties and hardness indicators of the cladding layer of these sheets are shown in table 3.

To evaluate the service properties of bimetal, samples were selected from these sheets, on which the mechanical properties and hardness of the cladding layer were determined after heat treatment simulating the heat treatment of finished products: quenching from a temperature of 930 ° C with low temperature tempering at 200 ° C.

The mechanical properties of the final product and the hardness indicators of the cladding layer obtained on the samples after quenching and tempering are presented in table 4.

The hardness of the clad layer in the delivery state should be taken as an indicator of the processability of bimetallic rolled products — after hot rolling or after hot rolling, followed by annealing. If the hardness after annealing is less than 300 HB, bimetal is evaluated as having high manufacturability in the manufacture of products.

The hardness of the cladding layer and the tensile strength of bimetallic rolled products after quenching and tempering are taken as indicators of wear resistance. It was experimentally established that the wear resistance is high if the hardness value is not less than 62 HRC, and the value of tensile strength is not less than 950 N / mm ² .

The use of annealing for sheets of options 1-4,6 led to a significant decrease in the hardness of the cladding layer compared to option 5 (without annealing): the hardness decreased from 350 HB to 300 HB or less (see table 3). Of the options with annealing, the highest hardness value of 300 HB was obtained after annealing at a temperature of 670 ° C (option 2 - insufficient processability). This indicates the need to use annealing at the stated temperatures to ensure high processability of bimetal.

From table 4 it follows that annealing at the stated temperatures is a prerequisite for ensuring high hardness of the cladding layer after quenching and tempering.

Satisfactory manufacturability in combination with a high service life have options 1, 3, 4 and 6, corresponding to the claims.

Table 1 The chemical composition of the steel of the base layer Option No. The content of elements, wt.% C Si Mn Cr P S Fe and impurities one 0.3 0.96 0.91 0.86 0.012 0.004 rest 2 0.33 1.01 0.98 0.93 0.011 0.003 rest 3 0.35 0.97 0.95 0.91 0.010 0.004 rest four 0.29 0.93 0.87 0.84 0.012 0.003 rest 5 0.29 0.93 0.87 0.84 0.012 0.003 rest 6 0.32 0.98 0.90 0.85 0.010 0.004 rest

table 2 The chemical composition of the deposited (cladding) layer Option No. The content of elements, wt.% C Si Mn Cr W V Mo P S Fe and impurities one 0.70 1.38 0.54 0.78 - - 0.005 0.013 0.003 rest 2 0.79 0.30 0.30 1.73 - - 0.02 0.012 0.005 rest 3 0.795 1,04 0.47 1.30 - - 0.018 0.014 0.003 rest four 0.85 0.29 0.37 1,58 - - 0.016 0.010 0.002 rest 5 0.85 0.29 0.37 1,58 - - 0.016 0.010 0.002 rest 6 0.80 1.10 0.52 1.40 0,098 0,039 0.02 0.012 0.005 rest

Table 3 Mechanical properties of bimetallic sheets before manufacturing Option No. Annealing temperature, ° C Yield strength, N / mm2 Tensile strength, N / mm2 Relative extension, % Hardness of base layer HB The hardness of the cladding layer HB Bend one 740 415 760 21.5 197 250 Oud 2 670 425 765 17.0 197 300 Oud 3 760 455 830 17.5 197 285 Oud four 745 450 810 17.5 207 280 Oud 5 without annealing 475 845 14.0 230 350 Oud 6 760 460 840 17.5 200 290 Oud

Table 4 Mechanical properties of the final product after quenching and tempering Option No. Yield strength, N / mm2 Tensile strength, N / mm2 Relative extension, % HRC Base Layer HRC cladding layer Bend one 540 910 18.0 34 62 beats 2 585 950 16,0 33 61 beats 3 580 970 14.0 34 63 beats four 570 960 13.0 35 63 beats 5 525 910 13.5 34 60 beats 6 590 975 13.0 34 64 beats

The working bodies of tillage machines were made of bimetal, the chemical compositions of the main and cladding layers of which are shown in tables 5 and 6.

Table 5 The chemical composition of the steel of the base layer No. of bimetal The content of elements, wt.% C Si Mn Cr P S Fe and impurities one 0.29 0.93 0.87 0.84 0.012 0.003 rest 0.35 0.97 0.95 0.91 0.010 0.004 rest 3 0.3 0.96 0.91 0.86 0.012 0.004 rest

Table 6 The chemical composition of the cladding layer No. of bimetal The content of elements *, wt.% C Si Mn Cr W V Mo P S one OP-1-1 9X1 0.83 0.29 0.37 1,58 0,078 0,035 0.016 0.010 0.002 2 9HS OP-1-2 0.85 1.20 0.47 1.25 0,085 0,039 0.018 0.014 0.003 3 OP-2-1 60S2HA 0.65 1.40 0.54 0.78 - - 0.005 0.013 0.003 * Iron and impurities - the rest.

Four plowshares were made of sheets whose material corresponds to bimetal 1 and 2. Before forming, the sheets were annealed at a temperature of 740 ° C and 750 ° C, respectively, then blanks were cut from the sheets, machining was carried out, hot bending was ensured to provide the desired shape, after which the products were quenched from a temperature of 930 ° C and released at a temperature of 220 ° C.

From the sheets, the material of which corresponds to option 3, the plow field board and the plow bit were made. Before forming, the sheets were annealed at a temperature of 730 ° C, then blanks were cut from the sheets, machining was performed, the products were quenched from a temperature of 920 ° C and released at a temperature of 200 ° C.

Conducted operational tests of the working bodies of tillage machines. Test conditions: soils of light and medium loamy texture, hardness (at a depth of 20 - 22 cm) - 1.8-3.3 MPa. The operating time for the working body (to failure) amounted to more than 30 hectares.

To confirm the legitimacy of the declared temperature ranges of hardening and tempering from sheets whose material corresponds to bimetal 1, four shares were made using the above technology, but the tempering and tempering temperatures of which went beyond the limits indicated in the claims.

Two plowshares were quenched from temperatures above (960 ° C) and below (840 ° C) as claimed in the claims and released at temperatures that did not correspond to those declared: 140 ° C and 260 ° C, respectively.

On the plowshares, after quenching from a temperature of 960 ° C, small surface cracks were found that propagated deep into the metal.

On plowshares hardened from a temperature of 840 ° C and tempered both at a temperature of 140 ° C and at a temperature of 260 ° C, the hardness of the cladding layer was 55-57 HRC, which is insufficient to provide the required wear resistance.

Thus, the technical result of the invention is to increase the adhesion strength of the layers, increase manufacturability in the manufacture of products, obtaining high strength, hardness and wear resistance of the finished product, as well as maintaining the optimal shape of the cutting blade during operation, is achieved when all the characteristics indicated in the formula are fulfilled inventions.

Claims (4)

1. A method of manufacturing the working bodies of tillage machines, including the shaping of the working bodies of hot-rolled bimetallic sheet and heat treatment, characterized in that the main layer of bimetal is made of alloy steel, containing, wt.%:
carbon 0.10-0.50,
silicon 0.5-1.5,
manganese 0.5-1.5,
chrome 0.5-1.5,
phosphorus no more than 0,025,
sulfur no more than 0,025,
iron and unavoidable impurities - the rest,
the cladding layer is made of highly alloyed wear-resistant steel, containing, wt.%:
carbon 0.7-1.2,
silicon 0.1-1.7,
manganese 0.15-0.80,
chrome 0.6-2.0,
molybdenum to 0.3,
phosphorus no more than 0,025,
sulfur no more than 0,025,
iron and unavoidable impurities - the rest,
and applied to the main layer by electroslag surfacing, before forming, the sheet is annealed at a temperature of 680-820 ° C, and the working bodies are heat treated by quenching from a temperature of 850-950 ° C and tempering at a temperature of 150-250 ° C. 2. The method according to claim 1, characterized in that the steel cladding layer further comprises, wt.%: Tungsten 0.02-1.0 and vanadium 0.02-0.2. 3. The method according to claim 1 or 2, characterized in that the formation of field boards, opposing plates, discs, chisels of the plow includes cutting blanks from a sheet and machining. 4. The method according to claim 1 or 2, characterized in that the shaping of plowshares, paws includes cutting blanks from a sheet, machining, hot bending, providing the desired shape.