TW200417433A - Method of preparing iron-based components - Google Patents

Abstract

The present invention concerns a process for the preparation of high density green compacts comprising the steps of providing an iron-based powder essentially free from fine particles; optionally mixing said powder with graphite and other additives; uniaxially compacting the powder in a die at a compaction pressure of at least about 800 MPa and ejecting the green body. The invention also concerns the powder used in the method.

Description

说明 Description of the invention: [Technical field to which the invention belongs] The present invention relates to a combination of metal powders useful in the powder metallurgy industry. More particularly, the present invention relates to methods for preparing high density components using these compositions. [Previous technology] = Several advantages of using powder metallurgy to manufacture structural parts over traditional blending methods of full dense steel. In this way, energy consumption is low and material utilization is high. Beneficial: Another-important factor of the powder metallurgy route is the mesh shape or closeness: the shape < knife can be used directly after the sintering process without forming cost (such as sewing, sharpening, boring or grinding). Manufacture 'However, under normal dense steel materials have superior mechanical properties than ingredients. This is mainly due to the ten pores of the PM component: Therefore, continuous efforts are made to increase the density of the PM component to a value as close as possible to the density value of the fully dense steel. Among the methods used to achieve higher density PM components, the powder forging method has the advantage of obtaining a fully dense composition. However, this method is costly and is mainly used for the mass production of heavier components such as connecting rods. Fully dense materials can also be obtained from elevated pressures at high temperatures (such as hot isostatic pressing, Hlp), but this method is also costly. By using warm compaction, a method of compacting at an elevated temperature (typically performed at 120-250 °), the density increases by 2 gW, which results in a significant improvement in mechanical properties. However, the disadvantages of the warm compaction method include Additional investment and processing, other methods (such as double compression, double sintering, sintering at elevated temperature, etc.) can further increase the density. These methods will also further increase the cost of manufacturing 88871 and thus reduce the overall cost of efficiency. There is a need for a simple and less expensive method for the market for components that utilizes the superiority of powder metallurgy technology and improves the static and dynamic mechanical strength of high-density compacts. [Summary of the Invention] What is the beginning, degree The component can be obtained by using high pressure and tight pressure combined with rough powder. Yunyu—Shipping 4 «, ^ ^ Traditionally used powder (that is, powder including fine particles) cannot be compacted into a black lean $ System is not as strong as 4 degrees The problem of tight surface damage or deterioration 'This finding was unexpected. In particular, according to the method of the present month, the method includes providing an iron-based powder that is substantially free of fine particles. , If necessary, the "U knife" stone 1, and other additives are mixed, the uniaxial compaction of the powder in the mold under high pressure and the discharge of rhenium (referred to as post-sintering). [Embodiment] "High density"-the word means Compacts with a density of at least 73 g / em3. Of course it is also possible to manufacture components with lower density, but it is believed to be less interesting and interesting. The iron-based powder according to the invention Pure iron powder (such as atomized iron powder, foamed iron powder, reduced iron powder), eight people / τ) # knife alloyed steel powder and fully alloyed steel powder. Partial Diffusion Alloying II The end of the volume is partially with one or more Cu,

Qin and "〇Alloyed steel powder is better than # 〇 A

Cu, Ni, Cr, Mo, V, f η ”, 0, W, Nb, butadiene, A1, p, s, and B alloyed steel powders are preferred. Stainless steel powders are also interesting and interesting. As for Particle shape, particle 1 ^ ^ v, Yuru straw water spray is better in the irregular form. The jellyfish with irregular shape% 'iron powder 5F can be interesting and interesting. 88871 200417433 The present invention The important feature is that the powder used has coarse particles, that is, the powder is substantially free of fine particles. The term "substantially free of fine particles" means that less than about 5% of the powder particles have a particle size of less than 45 μm measured by the method described in SS-EN 24 497. Its size. By far the most interesting results have been achieved with powders consisting essentially of particles larger than about 106 μm and especially larger than 212 μm. The term "consisting essentially of" means that at least 50% (preferably at least 60% and most preferably at least 70%) of the particles have particle sizes greater than 106 μm and 212 μm, respectively. The maximum particle size can be about 2 mm. The particle size distribution of iron-based powders used in PM production is normally a Gaussian distribution with an average particle diameter in the range of 30 to 100 μm and about 10-3 0% less than 45 μm. Iron-based powders that are substantially free of fine particles can be obtained by removing finer portions of the powder or by making powders with the desired particle size distribution. The influence of particle size distribution and particle shape on compaction properties and compaction have been studied vigorously. Thus, U.S. Patent No. 86 discloses a method for manufacturing a PM device with a substantially linear, acicular metal particle with a triangular cross section having a theoretical density higher than 95%. . So US Patent 6

The particles are coated. Powder with coarse particles is also used to make soft magnetic components. No. 309 748 discloses a ferromagnetic powder.

Teaching because the particles of very low content are smaller than! 〇 Smaller than 147 μm. This patent μηι, the mechanical properties of components made from these rough, high-purity 88871 200417433 degrees powder are very low. In addition, the patent teaches that if high strength is required, it is impossible to increase the content of particles smaller than 147 μm without deteriorating the soft magnetic properties at the same time. This powder is therefore mixed with a specific amount of scale iron. Graphite that can be used in the composition according to the present invention is not mentioned in the patent, and the presence of graphite deteriorates the magnetic properties. A powder mixture including coarse particles is also disclosed in U.S. Patent No. 5,225,459 (European Patent No. 554 009), which also relates to a powder mixture for preparing soft magnetic components. None of these powder mixtures include graphite. -In the field of powder forging, it is also known to make pre-coated% of iron particles based on coarse particles in appliances. U.S. Patent No. 3,901,661 discloses such powders. The amount of lubricant and especially the lubricant that should not be contained in this patent should be 1% by weight (Example U ° If the powder according to the invention is mixed with such a high amount of lubricant, then it will not be possible to achieve high density In order to obtain compacts with satisfactory sintering properties of the sintered parts according to the present invention, it is necessary to add a specific amount of graphite to the powder mixture to be compacted. In this way, 0.1- 1% of stone_ink 'is most preferably 0.2-1.0% by weight, preferably 0-2_08% by weight. Other additives can be added to the iron-based powder before compaction, such as including Mn, Cu,

The alloying elements of Nl, Cr, Mo, v, Co, W, Nb, Ti, A, P, S, and B can be added up to 10% by weight of these alloying elements. Additional additions J are machinability enhancing compounds, hard phase materials and flow agents. Iron-based powders can also be combined with a lubricant (internal lubrication) before moving into the mold. Add lubricant during the compression step to reduce friction between metal powder particles and between particles and the mold. Examples of suitable lubricants are stearates, paraffins, fats 88871 200417433 fatty acids and their derivatives, lubricants, polymers and other organic matter. Lubricants are added in the form of particles, which is good for human rights, but can be combined and / or empty on the particles. The amount of lubricant added to the iron according to the present invention can be changed between 6% and 6% based on the weight of the mixture, but it is better. The method according to the present invention can also be used. Wall lubrication), at this time, supply the mold wall lubrication combination before pressing. The term "under high pressure" can also be used for external and internal lubrication, meaning at a pressure of at least 800 MPa, interesting results are obtained at higher pressures such as pressures higher than 900 MPa. It is more preferable to be more than 1,000, and more preferably more than 1 100 MPa. It takes a lot of effort to eject the compact from the mold. Accompanied by the high wear of the mold and the fact that the component surface tends to be less shiny or damaged, the traditional compaction under high pressure (that is, the pressure is higher than 800 Mpa and the powder including fine particles is traditionally used. In a small amount of lubricant) (In a mixture of less than 0.6% by weight) is usually considered = combined. By using the powder according to the invention, it has been found that components with reduced discharge forces at high pressures (about 1 MPa) and acceptable or even perfect surfaces can also be obtained without the use of mold wall lubrication. Compaction can be performed in a standard installation, which means that the new method can be carried out without expensive investment: Compact in a single-step environment or elevated temperature and perform the operation in a single glaze. Another option-compaction can be carried out with the help of a patent announcement, Touching Heart 3 ^ $ Convergence and Vibration Machine (Hydropulsor Model Ηγρ 35-4). The k junction can be performed at a temperature normally used in the PM field (such as a standard temperature of 1080 to 160) or higher than 16 (a higher temperature of rc) and in a traditional use atmosphere. -10- (% 871 200417433 Other treatments of wet or sintered components can be applied in the same way, such as machining, surface hardening, surface densification, or other methods used in PM technology. In short, the advantages obtained by using the method according to the invention are High-density wet compacts can be manufactured economically. The new method allows the manufacture of higher-density components that are not easily manufactured using conventional technology. Additional standard compaction equipment can be used to manufacture high-density compacts that can be scaled or even perfect surface finish Tight objects. Examples of products suitable for manufacturing by new methods are connecting rods, gears and other structural parts subject to the same load I. By using stainless steel powder rims are particularly interesting 0-

The invention is further described by the following examples. Example 1 Two different iron-based powder compositions according to the present invention were compared with a standard iron-based powder composition. All three compositions are based on Swedish Hoganas ab

Made by Astaloy Mo. Add 2% by weight of graphite and 0.4% by weight of lubricant (Kenolube ™) to the composition. In one of the iron-based powder compositions according to the present invention, 'Astaloy Mo particles having a diameter of less than 45 µm are removed, and in other compositions according to the present ignorance, the particles of Astaloy Mo are smaller than 21 2 µm. Compaction is performed at ambient temperature and in standard equipment. As can be seen from Figure U, powders with a particle size greater than 212 μm give a clear increase in density at all compaction pressures. Figure 1-2 shows that in order to obtain the composition without damaging the surface, the most important factor is the reduction or removal of small particles (ie particles smaller than 45 μm). In addition, it can be seen from this figure that the force required to discharge a compact made from an iron-based powder composition without particles less than 212 μπι is compared to a standard iron-based 11-88871 with a particle size of about 20% and less than 45 μιη particles. The discharge force required for the manufactured compact is significantly reduced. The discharge force required for compacts made from bright iron-based powder compositions without particles smaller than 45 μm is also reduced compared to standard powders. It is worth noting that the discharge force for making compacts according to the present invention decreases with increasing discharge pressure, but the opposite is true for standard compositions. It is also observed that the compacts which have been stubborn have a damaged surface when the standard powder is compacted at a pressure higher than 700 MPa and is therefore unacceptable. When powders with substantially no particles smaller than 45 μm are compacted at a pressure higher than 700 Mpa, <compacting materials, less shiny surfaces, are less acceptable in some environments. Example 2 Repeat Example 1 but use 0.5% EBS (ethylene distearylamine) as a lubricant and compact it on a vibrating machine (Swedish ^^ (11 ^ 口 1115〇1 * Model 11ā? 35-4 ) With the help of Fig. 2-1 and 2-2 respectively, it can be noticed that the powder composition according to the present invention has a higher wet density and a lower discharge capacity than a powder composition with a standard powder. .It can also be noticed that the components produced by the standard powder have damaged surfaces under all compaction pressures. [Simplified illustration of the drawing] Figure 1 -1 shows two iron-based powder compositions and standard iron-based powders of the present invention. Density curves of the composition under different compacting pressures. Figures 1-2 show the discharge force curves of the two iron-based powder compositions and standard iron-based powder compositions of the present invention under different compacting pressures. Figure 2 -1 In order to show the density curve of the iron-based powder composition of the present invention and the standard iron-based powder S8871 -12-200417433 under different pressing pressures, Fig. 2-2 shows the iron-based powder composition of the present invention and the standard iron-based powder. Discharge force curve of powder composition under different compacting pressures. -13-88871

Claims (1)

200417433 Scope of patent application ... 1 A method for preparing a high-density wet compaction, comprising the following steps:-providing an iron or iron-based powder, wherein less than about 5% iron-based powder particles have a size of less than 45 μm; If necessary, mix the powder with graphite and other additives;-uniaxially compact the powder in the mold under a compaction pressure of at least about 800 MPa and-discharge the wet billet from the mold. _ 2. The method according to item 1 of the scope of patent application, wherein the compaction is performed in a single step | 3. The method according to item 1 or 2 of the patent application range, wherein at least 50% of the iron-based powder is composed of particles having a particle size greater than about 106 μm, preferably at least 60% and most preferably at least 70%. 4. The method according to any one of claims 1 to 3, wherein at least 50% of the iron-based powder is composed of particles having a particle size greater than about 212 μm, preferably at least 60% and at least 70%. good. 5. The method according to item 4 of the patent application, wherein the maximum particle size is approximately 2 mm ° 6. The method according to any one of item 2 to 5, wherein the graphite is present in an amount of 0.1-1.0%. 7. The method of any one of claims 1 to 6 of the claim # patent range, wherein the iron-based powder is combined with the lubricant in an amount between 0.05 and 0.6% by weight before compaction. 8. The method according to any one of claims 1 to 6, wherein the pressing is performed in a lubricated mold. 88871 9. The method according to any one of items 7 to 8 of the scope of patent application, wherein the pressing is performed using a combination of internal and external lubrication. 10. The method according to any one of items 1 to 9 of the scope of patent application, wherein the additive is selected from alloy elements such as Mn, Cu, Ni, Cr, Mo, V, Co, W, Nb, Ti, A1'P , S &amp; B mechanical processing performance increasing agent, a group of hard phase materials and flow agents. 11. The method of any one of claims 1 to 10 in the scope of patent application, wherein the compaction is performed at a pressure of at least 900 MPa, preferably at least 1,000 and most preferably above 1100 MPa. 12. The method according to any one of claims 1 to 丨 丨, wherein the compaction is performed at ambient temperature. 13. The method according to any one of claims 1 to 丨 丨, wherein the compaction is performed at an elevated temperature. 14. The method according to any one of claims 1 to 3, which is used for preparing a sintered product, the method further comprises a single sintering step higher than that. 15. A powder composition comprising iron or iron-based powder, wherein less than about 5% of the powder particles have a size of less than 45 μm, and contain 0.1 to 1.0% by weight of graphite. 16. The powder composition according to item 15 of the patent application scope, which further includes a lubricant in an amount of 0.05-6 wt%. 17. For the composition of claim 15 or 16, the particle size of at least 50% of the iron-based powder is greater than about 106 μm, preferably at least 60% and more preferably at least 70%. 18. The composition as claimed in item 17 of the patent application, wherein at least 50 () /. The iron-based powder 88871 200417433 has a particle size greater than about 2 1 2 μιτι, 19. A composition as set forth in any one of items 15 to 18 of the patent scope of Shen Qing, which further includes a component selected from alloy elements such as Mn, Cu, Ni, Cr, Mo, V, Co, W, Nb, Ti, A1, P, S, and B. Mechanical processing performance enhancers, hard phase materials and flow additives. 88871