Balancing block for compressor and preparation method thereof

Abstract

This invention belongs to the field of compressor manufacturing, specifically disclosing a balance block for compressors and its preparation method. The chemical composition of the balance block for compressors of this invention, by mass ratio, is: carbon 0.5-1%, manganese 13-16%, nickel 0.5-2.5%, vanadium 0.04-0.2%, silicon 0.4-0.9%, chromium ≤0.25%, sulfur ≤0.08%, phosphorus ≤0.09%, with the balance being iron and unavoidable impurities. This invention improves the tensile strength of the balance block by controlling its chemical composition and internal structure. Simultaneously, it improves the heat treatment method during the preparation process, thereby enhancing the tensile strength, wear resistance, and corrosion resistance of the balance block.

Description

Technical Field

[0001] This invention belongs to the field of compressor manufacturing, specifically relating to a balance block for compressors and its manufacturing method. Background Art

[0002] The balance weight is a crucial component of the compressor rotor, serving functions such as balancing, noise reduction, and vibration damping. Balance weights generally require high density, precise dimensional accuracy, high weight accuracy, and rust resistance. Furthermore, with advancements in technology, the performance requirements for compressor rotors are becoming increasingly stringent. In addition to meeting the aforementioned basic performance requirements, balance weights must also possess good mechanical properties, wear resistance, and be non-magnetic or have extremely low magnetic properties. However, traditional balance weight composition and manufacturing methods struggle to achieve ideal high strength and wear resistance. Therefore, there is still a need to continue developing a new type of balance weight to meet practical needs and broaden its application scenarios. Summary of the Invention

[0003] To address the issues of low strength in the existing balance blocks, the present invention provides a balance block for compressors and a method for its preparation.

[0004] To achieve the above objectives, the following technical solutions are specifically included:

[0005] A balance block for a compressor has the following chemical composition by mass: carbon 0.5-1%, manganese 13-16%, nickel 0.5-2.5%, vanadium 0.04-0.2%, silicon 0.4-0.9%, chromium ≤0.25%, sulfur ≤0.08%, phosphorus ≤0.09%, with the balance being iron and unavoidable impurities.

[0006] This invention improves the tensile strength of the balance block by regulating its chemical composition and internal microstructure. Specifically, nickel, in conjunction with vanadium, stabilizes austenite or austenite formed from the transformation of ferrite or martensite during heat treatment, resulting in higher mechanical strength. Manganese and carbon are the main components forming austenite. Silicon acts as a deoxidizer in the balance block; the remaining silicon is dissolved in austenite and is a non-carbide-forming element. It reduces the solubility of carbon in austenite and promotes carbide precipitation in high-manganese steel. However, as the silicon content increases, the amount of carbide precipitates increases, which is detrimental to the stability of the austenite microstructure. Therefore, the silicon content is controlled to be no more than 0.9%.

[0007] As a further preferred embodiment of the present invention, the chemical composition of the balance block for the compressor, by mass ratio, is: carbon 0.5-1%, manganese 13-16%, nickel 1-1.5%, vanadium 0.08-0.15%, silicon 0.4-0.9%, chromium ≤0.25%, sulfur ≤0.08%, phosphorus ≤0.09%, with the balance being iron and unavoidable impurities.

[0008] In a preferred embodiment of the present invention, the mass ratio of nickel to vanadium is nickel:vanadium = (6-19):1.

[0009] In a further preferred embodiment of the present invention, the mass ratio of nickel to vanadium is nickel:vanadium = (9-11):1.

[0010] In the system of this invention, nickel and vanadium have a synergistic effect, and the tensile strength is even better if the mass ratio is as described above.

[0011] As a further preferred embodiment of the present invention, the chemical composition of the balance block for the compressor, by mass ratio, is: 0.6% carbon, 16% manganese, 1.5% nickel, 0.15% vanadium, 0.7% silicon, ≤0.25% chromium, ≤0.08% sulfur, ≤0.09% phosphorus, with the balance being iron and unavoidable impurities.

[0012] A method for preparing a balance block for a compressor includes the following steps:

[0013] (1) The raw materials are prepared according to the composition of the compressor balance block, the raw materials are melted, poured, and cooled to obtain cast steel;

[0014] (2) The cast steel is heat-treated in a non-oxidizing gas atmosphere, and then water-cooled. The water-cooled cast steel is then subjected to heat aging treatment to obtain a balance block for the compressor.

[0015] In a preferred embodiment of the present invention, the heat treatment is divided into two stages: the temperature of the first heat treatment stage is 400-600℃ and the time of the first heat treatment stage is 10-60 min; the temperature of the second heat treatment stage is 1000-1200℃ and the time of the second heat treatment stage is 30 min-2.5 h.

[0016] As a further preferred embodiment of the present invention, the temperature of the first heat treatment stage is 500-600°C.

[0017] The heat treatment of this invention is carried out in two stages. The first heat treatment stage can pre-modulate the internal stress of the cast steel to avoid excessive internal stress in the cast steel, which would cause the balance block to crack. At the same time, it improves the plasticity of the material and enhances its tensile strength.

[0018] In a preferred embodiment of the present invention, the heating rate of the heat treatment is 30-80℃ / h.

[0019] Heat treatment can reduce and eliminate the magnetism of cast steel, achieving non-magnetic or extremely low magnetism in the balance block. This invention utilizes the synergistic effect of nickel and vanadium to stabilize the austenite formed by the transformation of ferrite or martensite in the balance block during heat treatment, thereby obtaining a balance block with higher strength.

[0020] In a preferred embodiment of the present invention, the temperature of the heat aging treatment is 300-390℃, the time is 20min-1h, and the heating rate is 3-5℃ / min.

[0021] In a preferred embodiment of the present invention, the heat aging process is carried out at a temperature of 370°C for 30 minutes, with a heating rate of 5°C / min.

[0022] Heat aging treatment can refine the grain structure of heat-treated austenitic steel, thereby further enhancing the mechanical strength of the balance block.

[0023] In a preferred embodiment of the present invention, the melting temperature is 1500-1800℃ and the time is 20min-2h.

[0024] In a preferred embodiment of the present invention, the melting temperature is 1570-1650℃ and the melting time is 45 minutes.

[0025] In a preferred embodiment of the present invention, the cooling is natural cooling.

[0026] In a preferred embodiment of the present invention, the non-oxidizing gas atmosphere is hydrogen.

[0027] To prevent surface oxidation of cast steel during heat treatment, a non-oxidizing gas atmosphere should be used.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) This invention improves the tensile strength of the balance block by regulating its chemical composition and improving its internal structure.

[0030] (2) The present invention can stabilize the austenite formed by the transformation of ferrite or martensite in the balance block during heat treatment through the synergistic effect of nickel and vanadium, and obtain a balance block with higher strength.

[0031] (3) The present invention improves the tensile strength, wear resistance and corrosion resistance of the balance block by performing solid solution fine grain strengthening through heat aging treatment. Attached Figure Description

[0032] Figure 1 The results are metallographic test results of the balance block prepared in Example 1.

[0033] Figure 2 The results are the thermal analysis results of the equilibrium block in Example 1. Detailed Implementation

[0034] To better illustrate the purpose, technical solution, and advantages of this invention, specific embodiments will be used to further explain the invention below. All raw materials used in the following embodiments and comparative examples were purchased from the market.

[0035] Example 1

[0036] (1) Preparation of wax model and shell film

[0037] The wax material is processed through melting, wax injection, pressing, and assembly to prepare a wax mold assembly. The mortar and glue are mixed and then the wax mold assembly is immersed in the mixture. This process is repeated multiple times to prepare a smooth shell preform on the wax mold. The shell preform is then subjected to a high-temperature dewaxing process at 1700℃ and a shell mold firing process at 1120℃ for 45 minutes to obtain a sintered semi-circular shell mold.

[0038] (2) Smelting and casting

[0039] The raw materials for the compressor balance block are prepared according to the following weight ratio (100%): carbon 0.6%, manganese 16%, nickel 0.8%, vanadium 0.02%, silicon 0.7%, chromium ≤0.25%, sulfur ≤0.08%, phosphorus ≤0.09%, with the balance being iron. This mixture is smelted in an 80 kg medium-frequency furnace at 1570-1650°C for 45 minutes to obtain molten steel. The molten steel is then poured into a sintered shell at 1570-1650°C and allowed to cool naturally to obtain cast steel. Note that ordinary steel can be used first for batching, followed by the addition of other materials to save costs; for example, 45# steel is used in this embodiment.

[0040] (3) Heat treatment

[0041] The cast steel is placed in a belt heat treatment furnace, and a decomposed ammonia atmosphere is introduced (ammonia decomposes at 850℃, releasing hydrogen into the main furnace to protect the product surface and create a reducing atmosphere, which is beneficial for the densification of surface grains and improves corrosion resistance). The heating section of the front section of the belt heat treatment furnace is programmed as follows: the temperature of the first heat treatment stage is 500℃, the time of the first heat treatment stage is 30 min, the temperature of the second heat treatment stage is 1050℃, the time of the second heat treatment stage is 1.5 h, and the heating rate is 50℃ / h. After heat treatment, the cast steel is cooled through the cooling water channel in the rear cooling section. After cooling, the temperature is increased to the heat aging treatment temperature of 370℃ at a heating rate of 5℃ / min, held for 30 min, and then naturally cooled to obtain a balance block.

[0042] Examples 1-9 and Comparative Examples 1-7

[0043] The raw material component content of the balance block is detailed in Table 1. The preparation methods of Examples 2-9 and Comparative Examples 2-7 are the same as those of Example 1.

[0044] Table 1. Component content (in mass percentages) of the balance blocks of Examples 1-9 and Comparative Examples 1-7

[0045]

[0046]

[0047] Example 10

[0048] Compared with Example 1, the difference is that in step (3) of this example, after heat treatment, the temperature of the heat aging treatment is 300°C and the time is 1 hour.

[0049] Example 11

[0050] Compared with Example 1, the difference is that in step (3), after heat treatment, the temperature for heat aging treatment is 390°C and the time is 30 min.

[0051] Example 12

[0052] The difference from Example 1 is that the temperature of the first heat treatment stage is 400°C.

[0053] Example 13

[0054] The difference from Example 1 is that the temperature of the first heat treatment stage is 600°C.

[0055] Example 14

[0056] The difference from Example 1 is that the temperature of the first heat treatment stage is 700°C.

[0057] Comparative Example 8

[0058] Compared with Example 1, the difference is that the temperature of the first heat treatment stage is 1050°C (i.e., the heat treatment is not divided into stages).

[0059] Comparative Example 9

[0060] Compared with Example 1, the difference is that in step (3), no heat aging treatment was performed after the heat treatment.

[0061] Comparative Example 10

[0062] Compared with Example 1, the difference is that in step (3), after heat treatment, the temperature for heat aging treatment is 450°C and the time is 30 min.

[0063] Comparative Example 11

[0064] Compared with Example 1, the difference is that in step (3), after heat treatment, the temperature for heat aging treatment is 280°C and the time is 2h.

[0065] Comparative Example 12

[0066] Compared with Example 1, the difference is that in this comparative example, an equal amount of Cu is used to replace Ni, while the rest remains unchanged.

[0067] Comparative Example 13

[0068] Compared with Example 1, the difference is that V is replaced with an equal amount of Ti in this comparative example, while the rest remains unchanged.

[0069] Performance testing

[0070] (1) Tensile strength test at room temperature: The tensile strength and elongation are tested at room temperature according to GB / T228.1-2021;

[0071] (2) Magnetism: Magnetic properties were tested using a gaussmeter;

[0072] (3) The metallographic structure of the balance block of Example 1 was tested using a metallographic microscope in accordance with GB / T13298-2015. The test results are as follows: Figure 1 As shown;

[0073] (4) Thermal analysis: The thermal analysis test of the balance block was carried out in accordance with GB / T 1425-1996. The equipment was TGA German Netzsch 209F3.

[0074] Table 1. Performance test results of the balance block in the examples and comparative examples.

[0075]

[0076]

[0077] Depend on Figure 1 It can be seen that the metallographic structure of the balance block is austenite, with visible twins, coarse grains in the middle and finer grains at the edges. The surface of the balance block contains fine grains, forming a protective layer, which has good wear resistance, corrosion resistance, and high processing hardness.

[0078] Depend on Figure 2 It can be seen that the equilibrium block has no obvious reaction peak, no weight loss, and no thermal deformation below 500℃.

[0079] As can be seen from Examples 1-7 and Comparative Examples 1-3 and 12-13, in the system of the present invention, nickel and vanadium have a synergistic effect when combined. Through the synergistic effect of nickel and vanadium, the austenite formed after the transformation of ferrite or martensite in the balance block can be stabilized during heat treatment, resulting in a balance block with higher tensile strength. At the same time, the balance block obtained has extremely low magnetic properties. Furthermore, as shown in Examples 1, 6-7, and Comparative Examples 4-7, the balance block exhibits better tensile strength when the vanadium content is 0.08-0.15% and the nickel content is 1.0-1.5%, and the balance block has the optimal tensile strength when the mass ratio of nickel to vanadium is 9-11.

[0080] As can be seen from Examples 1, 10-11 and Comparative Examples 9-11, when preparing the balance block, thermal aging treatment can refine some of the grains inside the balance block and introduce precipitates, thereby strengthening the tensile strength of the balance block. However, the temperature and duration of thermal aging should not be too high, otherwise over-aging will occur, resulting in a significant decrease in tensile strength.

[0081] As can be seen from Examples 1, 12-14 and Comparative Example 8, pre-heat treatment at a relatively low temperature during heat treatment not only avoids the phenomenon of thermal stress causing cracking of the balance block, but also significantly improves the tensile strength of the balance block. The balance block obtained by pre-treatment at 500-600℃ has better tensile strength.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A balance block for a compressor, characterized in that, Its chemical composition, by mass ratio, is as follows: carbon 0.5-1%, manganese 13-16%, nickel 0.5-2.5%, vanadium 0.04-0.2%, silicon 0.4-0.9%, chromium ≤0.25%, sulfur ≤0.08%, phosphorus ≤0.09%, with the balance being iron and unavoidable impurities; the mass ratio of nickel to vanadium is nickel:vanadium = (6-19):1; The method for preparing the balance block for the compressor includes the following steps: (1) The raw materials are prepared according to the composition of the balance block for the compressor, the raw materials are melted and cast, and then cooled to obtain cast steel; (2) The cast steel is heat-treated in a non-oxidizing gas atmosphere, then cooled with water, and then the water-cooled cast steel is heat-aged to obtain a balance block for the compressor. The heat aging treatment is performed at a temperature of 300-390℃ for 20 min-1 h, with a heating rate of 3-5℃ / min. The heat treatment is divided into two stages: the temperature of the first heat treatment stage is 400-600℃ and the time of the first heat treatment stage is 10-60 min; the temperature of the second heat treatment stage is 1000-1200℃ and the time of the second heat treatment stage is 30 min-2.5 h.

2. The balance block for a compressor as described in claim 1, characterized in that, The chemical composition of the balance block for the compressor, by mass ratio, is as follows: carbon 0.5-1%, manganese 13-16%, nickel 1-1.5%, vanadium 0.08-0.15%, silicon 0.4-0.9%, chromium ≤0.25%, sulfur ≤0.08%, phosphorus ≤0.09%, with the balance being iron and unavoidable impurities.

3. The balance block for a compressor as described in claim 1, characterized in that, The mass ratio of nickel to vanadium is nickel:vanadium = (9-11):

1.

4. The balance block for a compressor as described in claim 1, characterized in that, The temperature of the first heat treatment stage is 500-600℃.

5. The balance block for a compressor as described in claim 1, characterized in that, The heat aging process is carried out at a temperature of 370°C for 30 minutes, with a heating rate of 5°C / min.

6. The balance block for a compressor as described in claim 1, characterized in that, The melting temperature is 1500-1800℃, and the time is 20min-2h.

7. The balance block for a compressor as described in claim 1, characterized in that, The cooling is natural cooling; the non-oxidizing gas atmosphere is hydrogen; the heating rate of the heat treatment is 30-80℃ / h.

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