Method for manufacturing hammer component having excellent abrasion resistance and impact resistance, and hammer component manufactured thereby

Abstract

The present invention relates to a method for manufacturing a hammer component having excellent abrasion resistance and impact resistance. The method for manufacturing a hammer component, according to the present invention, comprises the steps of: preparing a molten metal of high-manganese steel; preparing a sand casting system which comprises an upper mold and a lower mold separated from the upper mold and has a cavity, formed by the upper mold and the lower mold, in the shape of a hammer component; injecting the prepared molten metal into the lower mold; pressing the molten metal injected into the lower mold by operating at least one of the upper mold and the lower mold after positioning the upper mold on the lower mold; forming a component by solidifying the molten metal in a pressed state; and homogenizing and thermally treating the formed component.

Description

Method for manufacturing crusher parts with excellent wear resistance and impact resistance and crusher parts manufactured thereby

[0001] This invention was supported by the National Research and Development Project (Project Number: 1415174854, Project Number: 20015155, Ministry of Trade, Industry and Energy, Project Management Agency: Korea Institute of Industrial Technology Planning and Evaluation, Research Project Name: Steel Industry Re-leap Technology Development Project (R&D), Research Project Name: Surface-strengthened high-manganese steel casting manufacturing technology using sand mold pressure casting).

[0002] The present invention relates to a method for manufacturing a crusher part having excellent wear resistance and impact resistance, and to a crusher part manufactured by the method.

[0003]

[0004] Hammers are used across a wide range of industries, including mining, construction, power generation, iron and steel manufacturing, and the wear-resistant parts that make up the hammers are used as consumables.

[0005] Recently, the global increase in industrial and household waste has led to a demand for longer service life for wear-resistant components to reduce disposal costs. Furthermore, the need for components capable of withstanding extreme crushing conditions, such as recycling high-strength products and handling large volumes of shredded material, is growing.

[0006] For these crusher parts, they are manufactured by welding a manganese alloy with excellent wear resistance to parts manufactured from cast steel, or by gravity casting using cast steel with excellent wear resistance.

[0007] In the case of welding manganese alloys to parts manufactured from double-cast steel, cracks may occur along the welded area during use, causing the welded surface to easily detach. In addition, the welded area is easily corroded, resulting in a short replacement cycle.

[0008] In addition, as disclosed in Korean Patent Publication No. 2020-0084626, in the case of gravity casting using high-manganese steel with excellent wear resistance, the problem of cracks or corrosion in the weld zone is solved, but the impact resistance is low compared to the wear resistance, so there were limitations in applying it to an environment with extreme crushing conditions or extending the replacement cycle of consumables.

[0009] Additionally, impact resistance can be improved by adding expensive alloying elements, but this method has the problem of increasing manufacturing costs.

[0010]

[0011] An object of the present invention is to provide a method for manufacturing a crusher part having excellent wear resistance and impact resistance at low cost and a crusher part manufactured by the method.

[0012] The purpose of the present invention is not limited to the purpose mentioned above, and other purposes not mentioned will be clearly understood by those skilled in the art to which the present invention belongs from the description below.

[0013]

[0014] In order to achieve the purpose of the present invention, the present invention provides a method for manufacturing a shredder part according to the following (1) to (5) and a shredder part according to (6) to (8).

[0015] (1) A step for preparing a molten metal composed of C: 1.0 to 1.5 wt%, Si: 0.5 to 1.0 wt%, Mn: 18 to 25 wt%, Cr: 2.0 to 3.0 wt%, Ni: 0.3 to 1.0 wt%, P: 0.03 to 0.05 wt%, S: 0.003 wt% or less (more than 0 wt%), the remainder being Fe and other unavoidable impurities; A step for preparing a sand casting system including an upper mold and a lower mold separated from the upper mold, wherein a cavity formed by the upper mold and the lower mold forms a shape of a crusher part; A step for injecting the prepared molten metal into the lower mold; A step for positioning the upper mold above the lower mold, and then operating at least one of the upper mold and the lower mold to pressurize the molten metal injected into the lower mold; A step for solidifying the molten metal under pressure to form a part; A method for manufacturing a crusher part having excellent wear resistance and impact resistance, comprising: a step of homogenizing heat treatment on the molded part;

[0016] (2) A method for manufacturing a crusher part having excellent wear resistance and impact resistance, wherein the content of Mn in (1) is 21.5 to 23.0 wt%.

[0017] (3) A method for manufacturing a crusher part having excellent wear resistance and impact resistance, wherein in (1) or (2), the sand casting system further includes a moving device that moves at least one of the upper mold and the lower mold.

[0018] (4) A method for manufacturing a crusher part with excellent wear resistance and impact resistance, wherein the molten metal is injected while the temperature of the molten metal is controlled to 1,500 to 1,550°C in any one of (1) to (3).

[0019] (5) A method for manufacturing a crusher part with excellent wear resistance and impact resistance, wherein in any one of (1) to (4), the pressurization of the molten metal is performed at a pressure in the range of 500 to 1,500 Kgf / ㎟.

[0020] (6) A method for manufacturing a crusher part with excellent wear resistance and impact resistance, wherein in any one of (1) to (5), the homogenization treatment is performed by heating at 1,080°C to 1,120°C for 60 to 360 minutes and then water quenching.

[0021] (7) A crusher part manufactured by the method described in any one of (1) to (6), wherein the microstructure of the crusher part includes an austenite structure, and the average grain size of the austenite structure is 200 ㎛ or less, and the crusher part has excellent wear resistance and impact resistance.

[0022] (8) (7), a crusher component having excellent wear resistance and impact resistance, wherein the wear amount of the ASTM D 4060 wear test on the crusher component is 10 mg or less, and the impact absorption energy of the Charpy impact test on the crusher component is 200 J or more.

[0023]

[0024] The method for manufacturing shredder parts according to the present invention significantly improves wear resistance and impact resistance compared to shredder parts manufactured using conventional methods, without adding expensive alloying elements. This allows for the product to withstand extreme shredding environments and significantly extends the replacement cycle compared to conventional shredder parts.

[0025]

[0026] Figure 1 is a manufacturing process diagram of a shredder component according to an embodiment of the present invention.

[0027] FIG. 2 is a schematic diagram of a sand casting system used in manufacturing a crusher component according to an embodiment of the present invention.

[0028] Figure 3 illustrates a casting process using the sand casting system of Figure 2.

[0029] FIG. 4 is a photograph of a shredder component manufactured according to an embodiment of the present invention.

[0030] Figure 5 is a photograph of a crusher part manufactured according to a comparative example.

[0031] Figure 6 is an image of the microstructure of a crusher part manufactured according to an example and comparative example of the present invention observed with an optical microscope at 100x magnification.

[0032] Figure 7 shows the sampling locations of tensile specimens and impact specimens from crusher parts manufactured according to examples and comparative examples of the present invention.

[0033] Figure 8 shows the shape of a specimen for evaluating a wear resistance test of a crusher part manufactured according to an embodiment and comparative example of the present invention.

[0034]

[0035] Below, with reference to the attached drawings, embodiments of the present invention are described in detail so that those skilled in the art can easily implement them. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0036] Throughout this specification, whenever a part is said to "include" a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated.

[0037] The terms "about," "substantially," and the like used in this specification are used in a meaning that is at or close to the numerical value when manufacturing and material tolerances inherent in the meanings mentioned are presented, and are used to prevent unscrupulous infringers from unfairly exploiting the disclosure in which exact or absolute values ​​are mentioned to aid understanding of the present application.

[0038] Throughout this specification, references to “A and / or B” mean “A or B, or A and B.”

[0039] FIG. 1 is a process diagram of a method for manufacturing a crusher part having excellent wear resistance and impact resistance according to the first embodiment of the present invention.

[0040] Referring to FIG. 1, the method for manufacturing a crusher part according to the present invention largely includes a step of preparing a high-manganese alloy molten metal (S10), a step of preparing a sand casting system (S20), a step of injecting the molten metal into a lower mold (S30), a step of pressurizing the molten metal injected into the lower mold with the upper mold (S40), a step of solidifying the molten metal while under pressure (S50), and a step of homogenizing the solidified part (S60).

[0041] In the step (S10) of preparing a molten high-manganese alloy, the high-manganese alloy may preferably contain carbon (C): 0.8 to 1.5 wt%, silicon (Si): 0.5 to 1.0 wt%, manganese (Mn): 18 to 25 wt%, chromium (Cr): 1.0 to 4.0 wt%, nickel (Ni): 0.1 to 1.0 wt%, phosphorus (P): 0.1 wt% or less, sulfur (S): 0.1 wt% or less, the remainder iron (Fe) and other unavoidable impurities.

[0042] The above carbon (C) is a component that forms carbides with other elements to provide strength and hardness. If it is less than 0.8 wt%, it is difficult to obtain the strength and hardness required for crusher parts, and if it exceeds 1.5 wt%, toughness (impact resistance) or corrosion resistance may deteriorate. Therefore, it is preferably included in an amount of 0.8 to 1.5 wt%, and 0.9 to 1.3 wt% is more preferable. The above silicon (Si) is a component that increases the strength of the material through deoxidation and solid solution strengthening of the molten metal. If it is less than 0.5 wt%, it is not sufficient to obtain the above effect, and if it exceeds 1.0 wt%, toughness may deteriorate. Therefore, it is preferably included in an amount of 0.5 to 1.0 wt%. The manganese (Mn) above is an austenite stabilizing element that ultimately allows the formation of an austenite structure. If the manganese (Mn) content is less than 18 wt%, ductility may decrease when other phases are formed due to a decrease in austenite stability. If it exceeds 25 wt%, mechanical properties may deteriorate. Therefore, 18 to 25 wt% is preferable, and 21.5 to 23 wt% is more preferable. The chromium (Cr) above is a component that forms carbides to stabilize grains and provide strength. If it is less than 1.0 wt%, it is difficult to obtain the strength required for crusher parts. If it exceeds 4.0 wt%, toughness (impact resistance) deteriorates. Therefore, 1.0 to 4.0 wt% is preferable, and 2 to 3 wt% is more preferable. The above nickel (Ni) is a component that enhances toughness through solid solution strengthening. If it is less than 0.3 wt%, the effect of enhancing toughness is not sufficient. If it exceeds 1.0 wt%, the effect of addition is minimal except for large castings, making it uneconomical. Since viscosity and toughness can be achieved even if Ni is added at 1.0 wt% or less, 0.3 to 1.0 wt% is preferable. The above phosphorus (P) and sulfur (S) are components that lower hot workability, and therefore it is preferable to manage them to be 0.1 wt% or less each.

[0043] In addition, in the step (S10) of preparing a molten high-manganese alloy, the molten metal is melted by heating the prepared raw materials weighed according to the alloy composition using an electric induction melting furnace, and at this time, a deoxidizer such as Ca-Si can be used to remove oxygen contained in the molten metal.

[0044] In the step (S20) of preparing a sand casting system, a sand casting system (100) such as that illustrated in FIG. 2 may be used, for example. Referring to FIG. 2, the sand casting system (100) includes an upper mold (110), a lower mold (120) disposed below and separate from the upper mold (110), and a moving means (130) for moving the upper mold (110) so that the upper mold (110) can be pressed against the lower mold (120). The upper mold (110) and the lower mold (120) are preferably made of sand mold. The movable means (130) includes two guide bars (131) that are slidably coupled to both ends of the upper mold (110), a mounting bar (132) that is fixed across the two guide bars (131), and a pressure cylinder (133) that is fixed to the mounting bar (132), and the movable end of the pressure cylinder is coupled to the upper mold (110), so that the upper mold (110) moves up and down by the extension and contraction action of the movable end of the pressure cylinder. The guide bar (131) is fixed to a fixing member (140) that fixes the casting system. It should be understood that the present invention is not limited to the sand casting system illustrated in FIG. 2, and can be applied without limitation as long as it can pressurize the molten metal injected into the lower mold to the upper mold.

[0045] The step (S30) of injecting molten metal into the lower mold is a step of injecting molten metal into the lower mold (120) after separating the upper mold (110) and the lower mold (120) of the sand casting system, as illustrated in FIG. 3 (left side of the drawing). At this time, the molten metal temperature (output temperature) when injecting the molten metal is preferably controlled to 1,500 to 1,550°C for performing the subsequent molten metal pressurization process, and a more preferable molten metal temperature (output temperature) is 1,520 to 1,530°C.

[0046] The step (S40) of pressurizing the molten metal injected into the lower mold by the upper mold is, as illustrated in FIG. 3 (right side of the drawing), to pressurize the molten metal in the lower mold (120) by moving the upper mold (110) toward the lower mold (120) into which the molten metal has been injected using the movable means (130). At this time, if the pressure applied to the molten metal is too low, the wear resistance and impact resistance of the obtained crusher parts may deteriorate, and if the pressure applied to the molten metal is too high, there is a risk of the mold being damaged. Therefore, considering the strength of the mold, it is preferable to pressurize at a pressure in the range of 500 to 1,500 Kgf / mm2, and it is more preferable to pressurize at a pressure in the range of 900 to 1,100 Kgf / mm2.

[0047] The pressurized solidification step (S50) is a step in which the pressurized molten metal is cooled to transform the liquid molten metal into a solid state. The molten metal can be removed from the mold after cooling to room temperature, but removal is also possible before that.

[0048] The homogenization process (S60) for solidified parts involves heating the solidified parts at 1,080 to 1,120°C, the austenite single-phase region of high-manganese steel, for 60 to 360 minutes, followed by water quenching. This process removes the dendritic structure formed during the casting process and obtains an austenite single-phase structure.

[0049]

[0050] <Example>

[0051] The alloy raw materials were measured to obtain the composition shown in Table 1 below, charged into an electric induction melting furnace, melted, and deoxidized using a Ca-Si deoxidizer.

[0052] Ingredients CSiMnPSCrNiFeContent (weight%)1.10.822.30.1 or less0.05 or less2.50.55Bal.

[0053] Afterwards, a ladle was used to pour the molten metal into the mold, and a torch was used to maintain the ladle surface at over 800℃ to slow down the cooling rate of the molten metal, and the final pouring temperature was measured to be 1,520-1,530℃.

[0054] After the melting, using the device shown in Fig. 2, a cavity in the shape of a crusher part was formed, and the molten metal was injected into a lower mold made of sand, and then the upper mold made of sand was attached to a movable device (press) and moved to the lower mold to pressurize the molten metal to about 1,000 kgf / ㎟, and the molten metal was sufficiently cooled for more than 12 hours in a pressurized state.

[0055] After separating the solidified crusher parts from the mold, a desanding process was performed to remove sand attached to the casting surface.

[0056] Next, the crusher parts were subjected to a homogenization treatment by heating them at 1,100°C, which is the austenite single-phase region of high manganese steel, for 2 hours, followed by a heat treatment by water quenching.

[0057] In order to remove foreign substances from the surface of the heat-treated shredder part, a shot blast or polishing process was performed until the foreign substances were sufficiently removed, thereby obtaining a shredder part as shown in Fig. 4.

[0058]

[0059] <Comparative Example>

[0060] For comparison with the example, a sand mold having a cavity in the shape of a crusher part was manufactured, and then the molten metal was poured into the sand mold at the same melting and pouring temperatures as in the example, and sufficiently cooled for 12 hours or more.

[0061] The process after separating the cooled crusher part from the mold was the same as in the example, and a crusher part as in Fig. 5 was obtained.

[0062]

[0063] microstructure

[0064] The crusher parts obtained through the examples and comparative examples were cut using a high-speed cutter, mirror-polished, etched in a 5% Nital solution for 30 to 50 seconds, and then the microstructure was observed using an optical microscope.

[0065] Microstructural observation results show that both the examples and comparative examples have a single-phase austenite structure. Furthermore, as confirmed in Fig. 6, the microstructure of the crusher component according to the examples was significantly smaller than that of the comparative example.

[0066] As a result of measuring this with an image analyzer, the average grain size of the austenite tissue of the example was found to be approximately 180 ㎛, while the average grain size of the austenite tissue of the comparative example was found to exceed 300 ㎛.

[0067]

[0068] Tensile properties

[0069] From the crusher parts of the examples and comparative examples, the portions shown in Fig. 7 were cut out, and tensile tests were performed at room temperature. For the tensile test, four specimens each for the examples and comparative examples were manufactured with a gauge length of 25 mm and a diameter of 5 mm according to the KS B 0802 test method, and the width, gauge length, parallel length, and loading speed of the specimens were measured to evaluate the yield strength, tensile strength, and elongation. Table 2 below shows the tensile test results (average value of four specimens).

[0070] Classification Comparison Example Tensile strength (MPa) 777818.5 Yield strength (MPa) 453459.8 Elongation (%) 3534.8

[0071] As shown in Table 2, the tensile strength of the examples was significantly improved compared to the comparative examples, the yield strength was slightly increased, and the elongation was similar.

[0072]

[0073] Impact characteristics

[0074] The portions shown in Fig. 7 were cut from the crusher parts according to the examples and comparative examples, and a Charpy impact test was performed at room temperature. For the Charpy impact test, four specimens each for the examples and comparative examples were manufactured, each having a square cross-section with a length of 55 mm, a height and width of 10 mm, and a V-notch, according to the KS B 0810 test method, and the Charpy impact test was performed to evaluate the Charpy impact absorption energy. Table 3 below shows the Charpy impact absorption energy results (average value of five specimens).

[0075] Charpy impact absorption energy (J) 145.4218.2

[0076] As shown in Table 3, it can be seen that the Charpy impact absorption energy of the crusher parts according to the example is improved by more than 70 J compared to the comparative example.

[0077]

[0078] Wear characteristics

[0079] After manufacturing the wear specimens shown in Fig. 8 from the crusher parts according to the examples and comparative examples, the mass change was measured after 1,000 cycles of rotation with a CS-17 wear wheel and a pressurized load of 1,000 g according to the ASTM D 4060 test method, and the wear amount was measured using the Weight Loss method (Weight Loss (mg) = Pre-abrasion specimen weight (mg) - Post-abrasion specimen weight (mg)), and is shown in Table 4 below.

[0080] Classification Comparison Example Example Wear amount (mg) 297

[0081] As shown in Table 4, the wear amount of the examples is significantly reduced compared to the comparative examples, and it can be seen that the wear resistance of the shredder parts according to the examples is significantly improved compared to the shredder parts according to the comparative examples.

[0082] Through a comparison of the tensile properties, impact properties, and wear properties of the above examples and comparative examples, it can be seen that a method for manufacturing a crusher part according to the present invention can obtain a crusher part with significantly improved wear resistance and impact resistance compared to a conventional one without additional addition of expensive alloy elements.

Claims

1. A step of preparing a molten metal composed of C: 1.0 to 1.5 wt%, Si: 0.5 to 1.0 wt%, Mn: 18 to 25 wt%, Cr: 2.0 to 3.0 wt%, Ni: 0.3 to 1.0 wt%, P: 0.03 to 0.05 wt%, S: 0.003 wt% or less (more than 0 wt%), the remainder being Fe and other unavoidable impurities; A step of preparing a sand casting system including an upper mold and a lower mold separated from the upper mold, wherein a cavity formed by the upper mold and the lower mold forms a shape of a crusher part; A step of injecting the prepared molten metal into the lower mold; A step of positioning the upper mold above the lower mold, and then operating at least one of the upper mold and the lower mold to pressurize the molten metal injected into the lower mold; A step of forming a part by solidifying the molten metal under pressure; and A step of heat treating the above-mentioned molded part; A method for manufacturing a crusher part having excellent wear resistance and impact resistance, comprising:

2. In paragraph 1, A method for manufacturing a crusher part having excellent wear resistance and impact resistance, wherein the content of Mn is 21.5 to 23.0 wt%.

3. In paragraph 1, A method for manufacturing a crusher part having excellent wear resistance and impact resistance, wherein the above-mentioned sand casting system further includes a moving device for moving at least one of the upper mold and the lower mold.

4. In paragraph 1, A method for manufacturing a crusher part having excellent wear resistance and impact resistance, wherein the molten metal is injected while the temperature of the molten metal is controlled to 1,500 to 1,550°C.

5. In paragraph 1, A method for manufacturing a crusher part having excellent wear resistance and impact resistance, wherein the pressurization of the above molten metal is performed at a pressure in the range of 500 to 1,500 Kgf / ㎟.

6. In paragraph 1, A method for manufacturing a crusher part with excellent wear resistance and impact resistance, wherein the above heat treatment is performed by heating at 1,080°C to 1,120°C for 60 to 360 minutes and then water quenching.

7. A crusher part manufactured by the method described in any one of clauses 1 to 6, The microstructure of the above crusher component includes an austenite structure, A crusher component having excellent wear resistance and impact resistance, wherein the average grain size of the austenite structure is 200㎛ or less.

8. In paragraph 7, The wear amount of the ASTM D 4060 wear test on the above crusher parts is less than 10 mg, A crusher component having excellent wear resistance and impact resistance, wherein the impact absorption energy of the Charpy impact test on the above crusher component is 200J or more.

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