Lightened high impact toughness powder metallurgy nonmagnetic steel product and method for manufacturing the same

Abstract

To provide a lightened high impact toughness powder metallurgy nonmagnetic steel product and a method for manufacturing the same.SOLUTION: A lightened high impact toughness powder metallurgy nonmagnetic steel product is manufactured by a powder metallurgy manufacturing step while mainly containing prealloyed powder a, prealloyed powder b, copper powder, and a binder as manufacturing raw materials. A particle diameter of the copper powder is 300 mesh or less, a weight ratio of the prealloyed powder a, the prealloyed powder b, and the copper powder is (60 to 80):(10 to 30):(9 to 15), and a used amount of the binder is 0.5% to 2.0% of the total weight of the prealloyed powder a, the prealloyed powder b, and the copper powder. The lightened high impact toughness powder metallurgy nonmagnetic steel product has nonmagnetic characteristics, has density of 6.5-7.0 g / cm3 and uncut impact toughness of 40-60 J / cm2, is lightweight, and has high impact toughness characteristics.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention belongs to the technical field of powder metallurgy and relates to a lightweight, high-impact toughness powder metallurgy non-magnetic steel product and a method for producing the same. [Background technology]

[0002] Powder metallurgy has advantages such as near-net shape, high material utilization, low production costs, and environmentally friendly manufacturing processes, and is widely used in the manufacture of materials and parts for automobiles, machinery, electronics, and other important fields. However, the density of powder metallurgy non-magnetic steel products is lower than that of non-magnetic steel products manufactured by conventional forging, and the material has low impact toughness, which makes it impossible to meet the usage requirements, greatly limiting the applications of powder metallurgy non-magnetic steel products.

[0003] The toughness of metallic materials can be improved by the composition and structural design of the metallic material, the processing of the metallic material, and the heat treatment method. In particular, doping with different elements or compounds can adjust the composition and structure of the material and change its physical and chemical properties. Copper is an alloying element commonly used in iron-based powder metallurgy materials. When the sintering temperature is higher than the melting point of copper, a transient liquid phase is generated, which promotes sintering densification and improves the toughness of the material. In addition, the impact toughness of iron-based powder metallurgy materials can also be improved by the copper infiltration process, but the impact toughness is relatively low (about 20 J / cm 2 ), it is difficult to meet the related high toughness and other special requirements.

[0004] Products manufactured using existing powder metallurgy manufacturing methods have low impact toughness, making it difficult to meet the required performance for some applications requiring high impact toughness. At the same time, weight reduction is also a trend in the automotive industry. Therefore, there is an urgent need to develop lightweight, high-toughness powder metallurgy high manganese steel products. Summary of the Invention [Problem to be solved by the invention]

[0005] One object of the present invention is to provide a lightweight, high impact toughness powder metallurgy non-magnetic steel product to solve at least one of the above technical problems.

[0006] Another object of the present invention is to provide a method for manufacturing the above lightweight, high impact toughness powder metallurgy non-magnetic steel product to solve at least one of the above technical problems. [Means for solving the problem]

[0007] According to one aspect of the present invention, there is provided a lightweight, high impact toughness powder metallurgy non-magnetic steel product, the manufacturing raw materials of which include pre-alloy powder a, pre-alloy powder b, copper powder and a binder.

[0008] In the present invention, the composition of the pre-alloy powder a is as follows: In weight percent, it contains C 0.4% to 0.7%, Si ≦ 0.8%, Mn 11.3% to 14.5%, P ≦ 0.03%, S ≦ 0.03%, and the balance is Fe; The composition of pre-alloy powder b is as follows: It contains, in weight percent, 1.2% to 1.8% C, ≦0.8% Si, 5.2% to 18% Mn, ≦0.03% P, ≦0.03% S, and the balance being Fe.

[0009] In some embodiments, the weight ratio of prealloy powder a, prealloy powder b, and copper powder may be (60-80):(10-30):(9-15).

[0010] In some embodiments, the copper powder has a particle size of 300 mesh or less.

[0011] In the present invention, pre-alloy powders A and B, which have different carbon and manganese contents, form an element concentration gradient network during the sintering process, which results in a high vacancy concentration gradient and thus increases the sintering diffusion driving force. The low-carbon, high-manganese pre-alloyed powder has a lower microhardness than the high-carbon, high-manganese pre-alloyed powder. Therefore, the synergistic use of pre-alloy powders A and B in the production of powder metallurgy non-magnetic steel products not only promotes the formation and growth of sintering necks between the high-strength high-manganese pre-alloyed powders, but also allows them to be formed at low pressing pressure using conventional powder metallurgy press equipment, effectively reducing production costs. The addition of high-content, small-particle copper powder, on the one hand, can improve the poor compressibility of pre-alloyed powders by adding copper. On the other hand, copper and manganese undergo a eutectic reaction at 870°C to form a copper-manganese alloy, reducing the activity of manganese. This effectively reduces the oxidation and volatility of manganese and enhances the stability of high-strength, high-toughness austerite substrates. The high-content copper dissolves in austerite during high-temperature sintering, providing solid-solution strengthening at a solid solubility ratio of less than 8%. The remaining copper also distributes into pores, forming continuous liquid-phase sintering. The remaining copper rapidly diffuses into the pores, forming closed sintering necks around the gaps. This closed sintering neck is strengthened by the solid-solution strengthening effect of the surrounding copper and the tendency of the gaps to change from irregular to circular due to continuous liquid-phase sintering, increasing toughness. As the sintering necks grow, most of the copper in the gaps gradually dissolves into the growing sintering necks, leaving small circular gaps. The high-strength, high-toughness austerite sintering necks formed during the sintering process using pre-alloyed powders of two different components, the solid-solution strengthening of the austerite substrate and sintering necks by the added copper element, the improvement of austerite stability and the harmful shape that causes substrate cracks in the sintering necks, and the reduction of the overall density improvement brought about by the gap filling by the copper element ultimately lead to improved impact performance and lighter material weight.

[0012] The lightweight, high impact toughness powder metallurgy non-magnetic steel product provided by the present invention has a density of 6.5 to 7.0 g / cm 3 and uncut impact toughness is 40-60J / cm 2 It not only has non-magnetic properties, but also is lightweight and has high impact toughness properties.

[0013] In some embodiments, pre-alloy powder a has a particle size of 150 mesh or less and said pre-alloy powder b has a particle size of 100 mesh or less.

[0014] In some embodiments, the binder may be a paraffin wax powder.

[0015] In some embodiments, the paraffin wax powder may be selected from a mixture of one or more of the following paraffin wax powder binders: zinc stearate, lithium stearate, aluminum stearate, and the like.

[0016] In some embodiments, the amount of binder used may be 0.5% to 2.0% of the total weight of prealloy powder a, prealloy powder b, and copper powder.

[0017] According to another aspect of the present invention, there is provided a method for producing the above-mentioned lightweight, high impact toughness powder metallurgy non-magnetic steel product, comprising: Mixing pre-alloy powder a, pre-alloy powder b, copper powder and a binder to obtain a mixed powder; pressing the mixed powder into a powder compact; and sintering the green compact.

[0018] The lightweight, high impact toughness powder metallurgy non-magnetic steel product provided by the present invention can be produced using sintering equipment and processes commonly used in powder metallurgy, resulting in low equipment investment costs.

[0019] In some embodiments, the mixed powder may be pressed into a green compact at a pressure of 900 to 1200 MPa.

[0020] In some embodiments, the density of the green compact is 6.0 to 6.6 g / cm 3 is.

[0021] In some embodiments, the sintering temperature when sintering the green compact may be 1150 to 1250° C., and the sintering time may be 0.5 to 1 hour. DETAILED DESCRIPTION OF THE INVENTION

[0022] The present invention will be described in more detail below with reference to the following embodiments. The examples are used for the purpose of explanation only and are not intended to limit the present invention in any way. Unless otherwise specified, the raw materials and reagents used in the examples are conventional products that are commercially available, and experimental methods for which no specific conditions are given in the examples are generally carried out according to conventional conditions in the art or conditions suggested by the manufacturers.

[0023] The method for producing prealloy powder A and prealloy powder B used in the present invention mainly includes the following steps: according to the desired prealloy powder composition, at least one of A3 steel, electrolytic manganese, low-carbon ferromanganese, and high-carbon ferromanganese is mixed in a certain ratio in an intermediate frequency furnace, melted at high temperature, deoxidized with rare earth ferrosilicon alloy, and then water atomized to obtain prealloy powders with the corresponding component contents and particle sizes, where prealloy powder A has a particle size of -150 mesh and prealloy powder B has a particle size of -100 mesh.

[0024] Zinc stearate was purchased from Guangzhou Qingfanxiang Material Technology Co., Ltd.

[0025] The copper powder particle size was -300 mesh or -100 mesh, and both were purchased from Weiken Powder New Materials (Beijing) Co., Ltd. [Example]

[0026] Example 1 (1) The component compositions of pre-alloy powder a and pre-alloy powder b used in this example are as follows: Pre-alloy powder a, having a particle size of 150 mesh or less, and having an elemental composition, in weight percent, of C 0.4%, Si 0.8%, Mn 14.44%, P 0.03%, S 0.03%, and the balance Fe; Pre-alloy powder b, having a particle size of 100 mesh or less, and having an elemental composition, in weight percent, of C 1.2%, Si 0.8%, Mn 6.23%, P 0.03%, S 0.03%, and the balance Fe; (2) Pre-alloy powder a, pre-alloy powder b, and copper powder (-300 mesh) were collected in a weight ratio of 62:28:10 to obtain a mixed powder. The carbon content of the mixed powder was calculated to be 0.58% and the Mn content was 10.70%. (3) Add 1.2% of zinc stearate by weight of the mixed powder to the mixed powder of step (2) and mix uniformly in a high-efficiency mixer; (4) The uniformly mixed powder is press-molded under a pressure of 950 MPa to produce a powder compact for a balance weight. The density of this powder compact is 6.35 g / cm 3 and (5) The balance weight compact is sent to a push boat furnace for sintering, the sintering temperature is 1250°C, and the sintering time is 1 hour. (6) The sintered green compact is polished and deburred to obtain a balance weight.

[0027] Example 2 (1) The component compositions of pre-alloy powder a and pre-alloy powder b used in this example are as follows: Pre-alloy powder a, having a particle size of 150 mesh or less, and having an elemental composition, in weight percent, of C 0.52%, Si 0.8%, Mn 13.21%, P 0.0103%, S 0.0204%, and the balance Fe; Pre-alloy powder b, having a particle size of 100 mesh or less, and having an elemental composition, in weight percent, of C 1.6%, Si 0.8%, Mn 12.88%, P 0.03%, S 0.03%, and the balance Fe; (2) Pre-alloy powder a, pre-alloy powder b, and copper powder (-300 mesh) were collected in a weight ratio of 72:17:11 to obtain a mixed powder. The carbon content of the mixed powder was calculated to be 0.65% and the Mn content was 11.70%. (3) Add 1.2% of zinc stearate by weight of the mixed powder to the mixed powder of step (2) and mix uniformly in a high-efficiency mixer; (4) The uniformly mixed powder is press-molded under a pressure of 1000 MPa to produce a powder compact for a balance weight. The density of this powder compact is 6.35 g / cm 3 and (5) The balance weight compact is sent to a push boat furnace for sintering, the sintering temperature is 1200°C, and the sintering time is 1 hour. (6) After sintering, the green compact is polished to remove burrs, and a balance weight is obtained.

[0028] Example 3 (1) The component compositions of pre-alloy powder a and pre-alloy powder b used in this example are as follows: Pre-alloy powder a, having a particle size of 150 mesh or less, and having an elemental composition, in weight percent, of C 0.7%, Si 0.8%, Mn 11.36%, P 0.0215%, S 0.03%, and the balance Fe; Pre-alloy powder b, having a particle size of 100 mesh or less, and having an elemental composition, in weight percent, of C 1.8%, Si 0.8%, Mn 18.00%, P 0.0103%, S 0.0204%, and the balance being Fe; (2) Pre-alloy powder a, pre-alloy powder b, and copper powder (-300 mesh) were collected in a weight ratio of 77:11:12 to obtain a mixed powder. The carbon content of the mixed powder was calculated to be 0.74% and the Mn content was 10.73%. (3) Add 1.2% of zinc stearate by weight of the mixed powder to the mixed powder of step (2) and mix uniformly in a high-efficiency mixer; (4) The uniformly mixed powder is press-molded under a pressure of 1150 MPa to produce a powder compact for a balance weight. The density of this powder compact is 6.35 g / cm 3 and (5) The balance weight compact is sent to a push boat furnace for sintering, the sintering temperature is 1170°C, and the sintering time is 1 hour. (6) After sintering, the green compact is polished to remove burrs, and a balance weight is obtained.

[0029] Comparative Example 1 (1) Pre-alloy powder a, having a particle size of 150 mesh or less, and having an elemental composition, in weight percent, of C 0.52%, Si 0.80%, Mn 13.21%, P 0.0215%, S 0.03%, and the balance being Fe; (2) Add 1.2% of zinc stearate by weight to prealloy powder a, and mix prealloy powder b and a binder uniformly in a high-efficiency mixer. (3) The uniformly mixed powder was press-molded under a pressure of 1150 MPa to produce a powder compact for a balance weight. The density of this powder compact was 6.35 g / cm 3 Controlled to (4) The balance weight compact is sent to a push boat furnace for sintering, the sintering temperature is 1200°C, and the sintering time is 1 hour. (5) After sintering, the green compact is polished to remove burrs, and a balance weight is obtained.

[0030] Comparative Example 2 (1) Pre-alloy powder a, having a particle size of 150 mesh or less, and having an elemental composition, in weight percent, of C 0.52%, Si 0.8%, Mn 13.21%, P 0.0215%, S 0.03%, and the balance being Fe; (2) Pre-alloy powder b, having a particle size of 100 mesh or less, and having an elemental composition, in weight percent, of C 1.6%, Si 0.8%, Mn 12.88%, P 0.0103%, S 0.0204%, and the balance being Fe; (3) The pre-alloy powder a and the pre-alloy powder b were mixed in a weight ratio of 78:22 to obtain a mixed powder, which was calculated to have a carbon content of 0.76% and a manganese content of 13.14%. (4) Add 1.2% of zinc stearate by weight of the mixed powder to the mixed powder of step (3) and mix uniformly in a high-efficiency mixer; (5) The uniformly mixed powder is press-molded under a pressure of 1250 MPa to produce a powder compact for a balance weight. The density of this powder compact is 6.35 g / cm 3 and (6) The balance weight compact is sent to a push boat furnace for sintering, the sintering temperature is 1200°C, and the sintering time is 1 hour. (7) After sintering, the green compact is polished to remove burrs, and a balance weight is obtained.

[0031] Comparative Example 3 (1) Pre-alloy powder a, having a particle size of 150 mesh or less, and having an elemental composition, in weight percent, of C 0.52%, Si 0.8%, Mn 13.21%, P 0.0215%, S 0.03%, and the balance being Fe; Pre-alloy powder b, having a particle size of 100 mesh or less, and having an elemental composition, in weight percent, of C 1.6%, Si 0.8%, Mn 12.88%, P 0.0103%, S 0.0204%, and the balance being Fe; (2) Pre-alloy powder a, pre-alloy powder b and copper powder were taken in a weight ratio of 70:20:10 to obtain a mixed powder, and the particle size of the copper powder was -100 mesh. The calculated carbon content and manganese content in the mixed powder were 0.68% and 11.82%, respectively. (3) Add 1.2% of zinc stearate by weight of the mixed powder to the mixed powder of step (2) and mix uniformly in a high-efficiency mixer; (4) The uniformly mixed powder is press-molded under a pressure of 1050 MPa to produce a powder compact for a balance weight. The density of this powder compact is 6.35 g / cm 3 and (5) The balance weight compact is sent to a push boat furnace for sintering, the sintering temperature is 1200°C, and the sintering time is 1 hour. (6) After sintering, the green compact is polished to remove burrs, and a balance weight is obtained.

[0032] Comparative Example 4 (1) Pre-alloy powder a, having a particle size of 150 mesh or less, and having an elemental composition, in weight percent, of C 0.52%, Si 0.8%, Mn 10.74%, P 0.0215%, S 0.03%, and the balance being Fe; (2) Pre-alloy powder a and copper powder are mixed in a weight ratio of 88:12 to obtain a mixed powder, and the particle size of the copper powder is -300 mesh; (3) Add 1.2% of zinc stearate by weight of the mixed powder to the mixed powder of step (2) and mix uniformly in a high-efficiency mixer; (4) The uniformly mixed powder is press-molded under a pressure of 1100 MPa to produce a powder compact for a balance weight. The density of this powder compact is 6.35 g / cm 3 and (5) The balance weight compact is sent to a push boat furnace for sintering, the sintering temperature is 1200°C, and the sintering time is 1 hour. (6) After sintering, the green compact is polished to remove burrs, and a balance weight is obtained.

[0033] Performance Test The performance of the balance weights manufactured in Examples 1 to 3 and Comparative Examples 1 to 4 was tested, and three samples were taken from each Example / Comparative Example and tested, and the average value was calculated.

[0034] The room temperature tensile performance test was conducted in accordance with GB / T 7964-2020 Room temperature tensile test for sintered metal materials (excluding hard alloys), and the tensile speed was 3 mm / min.

[0035] The density measurement was carried out in accordance with GB / T 5163-2006 Determination of permeable sintered metal material density, oil content and open porosity of sintered metal materials (excluding hard alloys).

[0036] The room temperature impact performance was measured in accordance with GB / T 9096-2002 Impact test method for sintered metal materials (excluding hard alloys).

[0037] The residual magnetic performance (Br) of non-magnetic steel products was measured in accordance with JB / T 14677-2022 Powder metallurgy high manganese non-magnetic steel balance weight technology for air conditioning compressors.

[0038] The results are shown in Table 1. [Table 1]

[0039] The above are only some embodiments of the present invention, and those skilled in the art may make various modifications and improvements without departing from the inventive concept of the present invention, and all such modifications and improvements shall fall within the protection scope of the present invention.

Claims

1. A lightweight, high-impact toughness powder metallurgy non-magnetic steel product, the manufacturing raw materials of which are pre-alloy powder a, pre-alloy powder b, copper powder, and a binder; The weight ratio of the pre-alloy powder a, the pre-alloy powder b, and the copper powder is (60-80):(10-30):(9-15), The amount of the binder used is 0.5% to 2.0% of the total weight of the pre-alloy powder a, the pre-alloy powder b, and the copper powder; The pre-alloy powder a contains, by weight, C 0.4% to 0.7%, Si≦0.8%, Mn 11.3% to 14.5%, P≦0.03%, S≦0.03%, and the balance being Fe; The pre-alloy powder b contains, by weight, 1.2% to 1.8% C, ≦0.8% Si, 5.2% to 18% Mn, ≦0.03% P, ≦0.03% S, and the remainder is Fe.

2. 2. The lightweight, high impact toughness powder metallurgy non-magnetic steel product according to claim 1, wherein the particle size of the copper powder is 300 mesh or less.

3. 3. The lightweight, high impact toughness powder metallurgy non-magnetic steel product according to claim 1, wherein the particle size of the pre-alloy powder A is 150 mesh or less, and the particle size of the pre-alloy powder B is 100 mesh or less.

4. 4. The lightweight, high impact toughness powder metallurgy non-magnetic steel product according to claim 3, wherein the binder is a paraffin-based wax powder.

5. 5. The lightweight, high impact toughness powder metallurgy non-magnetic steel product according to claim 4, wherein the paraffin wax powder is selected from at least one of zinc stearate, lithium stearate, and aluminum stearate.

6. The density of the lightweight, high impact toughness powder metallurgy non-magnetic steel product is 6.5 to 7.0 g / cm ３ and the uncut impact toughness is 40 to 60 J / cm ２ 5. The lightweight, high impact toughness powder metallurgy non-magnetic steel product according to claim 4, wherein:

7. Mixing pre-alloy powder a, pre-alloy powder b, copper powder, and a binder to obtain a mixed powder; pressing the mixed powder into a green compact; 3. The method for producing a lightweight, high impact toughness powder metallurgy non-magnetic steel product according to claim 1, further comprising the step of sintering and compacting the green compact.

8. 8. The method according to claim 7, wherein the mixed powder is pressed into a green compact under a pressure of 900 to 1200 MPa.

9. The density of the powder compact is 6.0 to 6.6 g / cm ３ The method according to claim 8, wherein

10. 8. The method according to claim 7, wherein the sintering temperature when sintering the powder compact is 1150 to 1250° C. and the sintering time is 0.5 to 1 hour.

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