JPH03170634A - Wear-resistant aluminum alloy for plastic working excellent in heat treating property - Google Patents

Abstract

PURPOSE:To manufacture the wear-resistant Al alloy for plastic working improved in heat treating properties by preparing an Al alloy contg. specified ratios of Si, Cu, Mg, Zn and P and having specified grain size of Si primary crystals and their occupying rate. CONSTITUTION:An Al alloy contg., by weight, >13 to 25% Si, >3.5 to 8% Cu, >0.3 to 5% Mg, >0.5 to 10% Zn, >0.001 to 0.05% P and the balance Al with inevitable impurties and in which >=90% of Si primary crystals in the ones having <=80mu grain size, the average grain size of the Si primary crystals is regulated to <=40mu and the areal occupying rate of the Si primary crystals is regulated to >=1% is prepd. In this way, the wear-resistant Al alloy for plastic working maintaining plastic workability and wear resistance almost equally to those of conventional ones and in which heat treating conditions are relaxed or a part or the whole of the heat treatment is obviatable can be obtd.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a wear-resistant aluminum alloy for plastic working, and more specifically, to a wear-resistant aluminum alloy for plastic working with improved heat treatment properties. It is something. [Prior Art] A390 alloy is a typical aluminum alloy that has been subjected to plastic working such as hot/cold forging and extrusion and has excellent wear resistance. A390 alloy has excellent wear resistance due to 5 primary crystal Si, but in order to exhibit even more wear resistance, it is subjected to solution treatment and artificial aging.
T treatment is performed to precipitate Al-Cu type, Mg-SL type, etc. precipitates. This T. The treatment is, for example, water quenching at 490°C for 2.5 hours, followed by heat treatment at 200°C for 2 hours. As a result, H
A product with a high hardness of about 180 Rl can be obtained. As an invention related to improving the plastic workability of wear-resistant aluminum alloys for plastic working, Si4-20%, FeO. L~1.0%
, Cu2.0-6.0%MnO. Of ~1.
0%, Mg0.2~2.0%, Cr0.01~l,
0%, Zn0.01~2.0%, N as necessary
There are aluminum alloys containing 0.01 to 2.5% i. According to the explanation, Zn is said to have the effect of improving plastic workability. The T6 treatment in the examples of this invention includes solution treatment at 430°C for 1 hour, followed by 170°C.
An example is shown in which aging treatment is carried out at 10°C for 10 hours. The T and processing conditions for alloys with the above compositions are shown in many other patent publications and industrial standards, and the holding temperatures and times are almost the same. [Problems to be Solved by the Invention] However, such T6 heat treatment requires too much time, requiring a total of 4 hours or more for solution treatment and return treatment, and in some cases 10 hours or more. It is necessary to increase the processing capacity of the heat treatment furnace, which is the cause of the increase in product costs. Furthermore, if one or both of solution treatment and high-temperature return treatment, which are conventionally always performed, can be omitted, the cost of the product can be significantly reduced. Therefore, the present invention provides a wear-resistant aluminum alloy for plastic working that can relax heat treatment conditions or omit part or all of heat treatment while maintaining plastic workability and wear resistance almost the same as conventional ones. The purpose is to provide. [A Thousand Steps to Solve the Problems] The present invention provides Si: more than 3% and Cu: 3.5% up to 25%.
% up to 8% Mg: over 0.3% up to 5% Zn: over 0.5% up to 1O% P: 0. It has a composition in which it contains more than 1% OO and up to 0.05%, with the remainder consisting of unavoidable impurities, and 90% (number percentage) of primary Si is 80 μm or less,
To provide a wear-resistant aluminum alloy for plastic working with excellent heat treatment properties, characterized in that the average particle diameter of primary Si is 40 μm or less, and the area occupation rate of primary Si is 1% (area %) or more. It is something. Furthermore, the present invention adds (a) Mn, Cr, Zr to the above composition.
Exceeding 0.05% and up to 2% of one or more of the following: (b)
One or more of Pb, Sn, and Bi in an amount exceeding 0.1% and up to 3%, (c) NL in an amount exceeding 0.5% and up to 3%, (ii) N
Heat treatment characteristics when one or more of a, Sr, and Sb types or two or more are added in an amount exceeding 0.001% to 0.5%, and (e) Fe is added in an amount exceeding 0.2% and up to 2%. We also provide aluminum alloys with excellent wear resistance for plastic working. The reasons for limiting the composition and structure in the present invention will be explained below. Si is a component that improves wear resistance by forming primary Si and eutectic Si, and if its content is less than 13% (percentages are by weight unless otherwise specified), wear resistance is poor. It is enough. On the other hand, if the Si content is 25% or more, plastic workability is inhibited. Cu exhibits heat treatability and has the effect of increasing the strength of the aluminum base, and if its content is less than 3.5%, age hardening due to heat treatment is insufficient. On the other hand, when the Cu content exceeds 8%, plastic workability is inhibited. Mg is a component that coexists with Cu and SL to exhibit heat treatability, and if its content is less than 0.3%, age hardening by heat treatment is insufficient. On the other hand, when the Mg content exceeds 5%, plastic workability is inhibited. Zn is a component that coexists with Mg and exhibits heat treatability, and is a component useful for shortening the holding time in heat treatment and omitting solution treatment and/or high temperature aging treatment. Furthermore, although frictional heat is generated during use of the part and the member is exposed to high temperatures, the degree of deterioration of mechanical properties at this time is less than that of a product that does not contain Zn. If the Zn content is 0.5% or less, no such effect is produced, while if it exceeds 10%, plastic workability is inhibited. P is an element necessary to refine primary Si. P
The content of o. If it is less than oot%, there is no effect, and if it is less than 0.0%.
If it exceeds 0.05%, it becomes excessive and no further effect can be expected. Note that P is present in the alloy of the present invention in the form of acid-insoluble P and acid-soluble P, and it is believed that the acid-insoluble P is useful for refining primary crystal Si. Mn, Cr, and Zr are preferable additive components for improving heat resistance strength and preventing coarsening of crystal grains due to recrystallization during plastic working. If the content (total amount when two or more types are contained) is 0.05% or less, no such effect is obtained, while if it exceeds 2%, plastic workability is inhibited. Pb, Sn, and Bi are preferable additive components for improving free machinability. If the content is 0.1% or less, no such effect will be obtained, while if it exceeds 3%, plastic workability will be inhibited. Ni is a preferable additive component for improving heat resistance strength. If the content is less than 0.5%, there is no effect of improving heat resistance strength, while if it exceeds 3%, plastic workability will be inhibited. Na, Sr, and Sb are preferable additive components for refining eutectic Si and improving forgeability. If the content is less than 0.001%, this effect is absent,
On the other hand, if it exceeds 0.5%, it becomes excessive and no further effects can be expected. Fe is a preferable addition for improving wear resistance. If its content is less than 0.2%, it has no effect, while if it exceeds 2%, it reduces corrosion resistance. As mentioned above, one of the characteristics of the alloy of the present invention is that the primary crystal Si is made fine by P.
i must satisfy the following requirements. (2) 90% or more of the primary Si particles have a particle size of 80 μm or less. Primary Si with a grain size exceeding 80 μm is extremely susceptible to cracking during plastic working, and when the aluminum alloy with SL small pieces produced by the cracks rubs against a mating material as a product, the Si pieces exposed on the friction surface fall off. and damage the other material. In order to prevent this, it is necessary to control the number of primary S1 particles having a particle size exceeding 80 μm. If the method described in (2) above is used, the primary crystal Si having a particle size exceeding 80 μm will be less than 10% of the total number, and even if the above-mentioned cracks occur, the wear of the mating material will not be significantly accelerated. @The average particle diameter of primary crystal Si is 40 μm or less. The average particle diameter is a value obtained by measuring the above particle diameters of all primary Si particles and averaging them. The larger the size of primary crystal Si, the more likely it is to break, so it is necessary to regulate the average particle size to a certain value or less. In AJ2-Si alloys, wear resistance is improved by the presence of eutectic Si, but in order to improve wear resistance, primary Si must be present in a certain amount or more. The amount is approximately determined by the Si content, but primary Si
It is necessary to directly determine the amount of primary Si because it varies considerably depending on the growth rate of α-Aβ, the amount of Si solid solution in α-Aβ, etc. The method for measuring the amount of primary crystal S1 is based on the method of measuring the area occupation rate (area %) of the primary crystal Si on the cross section or surface of the alloy material in any direction. If the area measured in this manner is less than 1%, the wear resistance will not be excellent. Therefore, in the present invention, primary S
i was set to be 1% or more. The primary Si structure as described above is obtained by the refinement effect of P and rapid cooling during casting. Moreover, in hypereutectic Si alloys, the distribution of primary Si in the ingot also greatly affects the wear resistance of parts used as members. That is,
If there is primary Si that has segregated in the ingot, primary S
Wear resistance is poor in areas where i is rough, while in dense areas it is easy to crack during forging, and primary crystal S during use.
i is likely to break off and fall off. In order to obtain a good primary Si structure, the manufacturing method of the ingot is very important. It is difficult to obtain an ingot with Si distribution. Furthermore, it is even more difficult to obtain an ingot exhibiting a uniform primary Si distribution using the metal mold casting method or the sand mold casting method. On the other hand, for example, casting a molten aluminum alloy using a gas pressurized semi-continuous casting method (Japanese Patent Publication No. 54-42847) at a cooling rate of 1° C./sec or more results in the above-mentioned structure. Recommended method for obtaining ingots. Furthermore, an aluminum alloy having the above structure can also be provided by a continuous casting method in which molten metal is poured between a pair of rolls. A desired shape is obtained by further subjecting the ingot or plate obtained by these methods to plastic working such as forging and extrusion. [Function] The heat treatment characteristics are improved by the alloy of the present invention, and the following A-C pattern heat treatment becomes possible. Note that pattern D corresponds to a heat treatment process that is generally performed, but it goes without saying that sufficient characteristics can be ensured even if the alloy of the present invention is heat treated in pattern D. Pattern A (hot forging → room temperature aging treatment): Hot forging, one water quenching → room temperature aging Pattern B (short time solution treatment, one room temperature aging treatment); Hot forging, one short time solution treatment → water quenching → room temperature aging Pattern C (short time T. treatment): Hot forging, short time solution treatment → water quenching, short time reversal treatment Pattern D (conventional process T6 treatment): Hot forging, normal solution treatment, water quenching, normal Hot forging in each of the above patterns may be replaced with cold forging → heating for solution treatment, or hot forging may be replaced with other processing methods such as hot extrusion or hot rotation processing. Good too. In pattern A, it is possible to obtain high strength simply by performing solution treatment at the temperature of the material at the end of forging and aging the supersaturated solid solution by water quenching at room temperature. This is an example that does not require return processing. In this example, the temperature after forging is 380 to 470°C, water quenching is performed immediately after forging, and then room temperature aging treatment is performed for 5 hours or more. In this pattern A, if normal temperature aging is replaced with high temperature return treatment, the desired hardness can be obtained in a shorter heat treatment time than the conventional T6 treatment. However, this pattern A
uses normal temperature aging to minimize the energy used for heat treatment. The purpose of patterns B and C other than pattern A is to minimize the energy used. In other words, the heat treatment method and method are designed to not only minimize heat treatment energy but also minimize heat treatment time.
Conditions can also be changed using these patterns. Pattern B is an example of short-time solution treatment in which the solution treatment time is short, for example, 1 to 60 minutes, and then room temperature aging is performed. This pattern performs short-time solution treatment in a continuous heat treatment type solution treatment furnace, and is suitable for increasing mass productivity. Pattern C performs short-time solution treatment in the same way as pattern B, but returns 150 to 250 Examples include short-time artificial aging treatment at 5 to 180 minutes, which is shorter than the conventional method, or artificial aging treatment at a lower temperature (but longer at room temperature or higher), for example, 50 to 150 degrees Celsius. . Pattern D is a normal T, processing process, and is 5400-5
After solution treatment at 20℃ for 2 to 6 hours,
This is an example in which artificial aging treatment is performed at 250°C for 2 to 24 hours. Furthermore, it is also possible to combine any of A, B, and C and perform a two-stage aging treatment of room temperature aging for about one week and subsequent T6 treatment, which further ensures the improvement in the strength of the material. Can be done. Conditions for the short-time T6 treatment include a holding time of 5 to 180 minutes at about 100 to 250°C. These heat treatment patterns are based on the desired advantages (for example, short processing time) and alloy compositional features (ease of solid solution, etc.).
(slow rate of precipitation, etc.) is selected as appropriate. [Examples] Hereinafter, the present invention will be explained in more detail with reference to Examples. Table 1 shows the chemical compositions of the alloys of the present invention and comparative alloys. Alloys with these chemical compositions are melted and cooled at a cooling rate of 15℃/
Diameter 67mm and 5℃/at a speed of sec or higher
After continuously casting an ingot with a diameter of 156 mm at a speed higher than sec, homogenization treatment was performed at 460°C and O material treatment at 390°C. From this, various accuracy tests were conducted to evaluate the material properties. The test method is as follows. After polishing the sample to a mirror finish using a polishing machine, an image analysis processing device (Luzex manufactured by Nireco Co., Ltd.,
5000) to replace the primary Si particle area with a circle with an equivalent area, and use that circle as a representative of the diameter.
The particle size distribution was determined by the equivalent circle diameter method using the primary Si particle size. From this, the average particle diameter and the area occupation rate of primary Si were measured. The observation magnification of primary Si was set to 50 to 200 times, depending on the size of each primary Si. For the particle size distribution of primary Si, a histogram of particle sizes was drawn, the abundance ratio of the particle size from O was determined, and the particle size when it reached 90% was defined as the "particle size of 90% of the particles". The measurement was carried out in the same manner as the measurement of the shape of the primary S particles of Si 1.
However, the microscope observation magnification was set to iooo times, and only the average particle size was determined. Tests were conducted using the upsetting forgeability testing device shown in Figure 1. In the figure, l is the upper punch, 2 is the lower patch, 3 is the test piece, and 4 is the press space. The test piece was a cylindrical rod with a shape of 20 mmφ x 20 mmh, and its upper and lower 1 mm were restrained by the upper bunch 1 and the lower bunch 2, respectively. With the test piece 3 set as shown in the figure, it was heated for 4 3 0'CX 30 minutes and compressed with the upper bunch 1. When micro-cracks occurred on the free deformation surface, the compression was stopped and the The upsetting rate was calculated as follows. In other words, the degree of difficulty in upsetting forging was determined by the upsetting rate. The hot upsetting forgeability evaluation criteria were as follows. O: Good upsetting forging property Upsetting rate 50% or more ×:〃
Defective Less than 50% red and 1 Using an Okoshi type abrasion tester, the specific wear amount of the sample material was measured to evaluate the abrasion properties. The measurement conditions are as follows. Lubrication conditions Non-lubricated mating material Bearing steel (SUJ-2) Hardness HRC55 Friction speed 3.62 m/sec Final load 2.13 kg Friction distance 600 m The evaluation criteria for wear resistance were as follows. O: Excellent wear resistance, specific wear amount less than 5 x 10 -'*m''/kgm
: Poor wear resistance. Specific wear amount is 5 x 10 -'mm"/kgm or more. The evaluation criteria for the main heat treatment characteristics under heat of 1 l were as follows: 0: Water quenched after hot forging, locked after being left at room temperature for 24 hours. Well B scale hardness (HRB) exceeds 80. ○: After hot forging, a short time solution treatment is performed and the hardness is 2 at room temperature.
H R B exceeds 80 after being left for 4 hours. Δ: HRB exceeds 80 by performing short-time solution treatment and further short-time return treatment after hot forging. ×: Normal T, H due to treatment (solution treatment, artificial aging treatment)
RB exceeds 80 or does not reach 80. This process takes a long time. Table 2 shows the evaluation results for each of these items and the overall judgment. (Left below) The present invention alloy Ko 1 was subjected to a short-time solution treatment at 490°C for 10 minutes, and after water cooling, a short-time return treatment at 190°C for 20 minutes. By applying the treatment (pattern C), an HRB hardness of 80 could be obtained, but compared to the comparative alloy FJctl2, which has almost the same composition except for Zn.
, No. 13, to obtain the same cure, 490°C,
Long-term T.I. treatment for a total of 4 hours including solution treatment for 2 hours and return treatment at 190°C for 2 hours. Since it was necessary to perform the treatment (pattern D), it is clear that the alloy of the present invention can complete the artificial aging treatment in a short time. At this time, the mechanical properties of the material, including hardness, obtained by short-term heat treatment are the same as those of the comparative alloy. The alloy of the present invention Na2 is 490℃
HRB82 is obtained by a short-time solution treatment of 20 minutes and an aging treatment at room temperature for 24 hours, making it possible to omit the heating and holding steps for return treatment. The alloy NllL3 of the present invention is hot forged at 450°C, immediately water quenched, and then aged at room temperature for 24 hours to obtain an HRB hardness of 81, making it possible to completely eliminate the solution treatment and return processes. . In other words, water quenching after hot forging and 1
A material with high hardness can be obtained by leaving it for several days. Alloys 4 and 7 of the present invention contain Mn or Ni. Comparative example 17
．． When Mn or Ni is contained as seen in 18,
Artificial aging characteristics tend to shift toward higher temperatures and longer times. However, in alloy seeds 4 and 7 of the present invention, both the solution treatment time and the return time can be shortened by adding Zn. Alloy No. of the present invention. 10 was cold forged,
After cold forging, solution treatment at 500℃ for 20 minutes and 210℃
, an altitude of HRB80 can be obtained with a 20-minute return process (pattern C). The primary crystal S1 particle size of the alloy Nll-11 of the present invention is 9
0% is 80 μm or less, and the average particle size is 40 μm
The upsetting forgeability and wear resistance were both good. On the other hand, comparative alloy NCL12,16 has 90% of primary Si particles.
was 95 μm and 85 μm, and the hot upsetting forging properties were poor. Comparative alloy No. Nos. 12, 13, 17, 19, and 20.21 do not contain Zn, so the T. It could not be processed and the heat treatment properties were poor. Among these, No. No. 19 was cold forged, but required heat treatment of pattern D, and required long T6 treatment. Comparative alloy Nal4 could be subjected to T6 treatment for a short time due to the effect of adding Zn, but its wear resistance was poor due to the absence of primary Si. Comparative alloy Nal5 had a low Mg content, so it could not be returned for a short time and its heat treatment properties were poor. On the other hand, comparative alloy No. Comparative alloy No. 18 had too much Mg and had poor hot forgeability. Comparative alloy No. 20 was a thick ingot with a diameter of 156 mm, and the grain size of the primary crystal S1 was larger than that of the thin rod, and the eutectic Because Si was coarse, hot forgeability was poor. [Effects of the Invention] As described above, according to the present invention, the heat treatment properties are excellent, and the heat treatment process can be omitted or even when heat treatment is performed, it is short. The present invention provides a wear-resistant aluminum alloy for plastic working, which enables time-long heat treatment and has plastic workability and wear resistance equivalent to conventional alloys.Therefore, the present invention provides low-cost compressor parts, automobile parts, and machine parts. , electrical equipment parts, etc., and greatly contributes to these industries.The invention according to claim 2 prevents recrystallization due to heat treatment after plastic working and has high mechanical properties, and the invention according to claim 3 further improves free machinability. The invention of claim 4 further improves the heat resistance, the invention of claim 5 improves forgeability by making the eutectic Si finer, and the invention of claim 6 further improves the forgeability by improving wear resistance. A more suitable alloy can be provided.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the upsetting forgeability test. 1...Top bunch 2...Lower bunch 3... Test material 4...Pre-space

Claims (1)

[Claims] 1. Si: More than 13% and up to 25% Cu: More than 3.5% and up to 8% Mg: More than 0.3% and up to 5% Zn: More than 0.5% and up to 10% P: Contains more than 0.001% and up to 0.05%, with the remainder consisting of unavoidable impurities, 90% or more of the primary Si crystals have a particle size of 80 μm or less, and the average particle size of the primary Si crystals is 40 μm. or less, and the area occupancy rate of primary Si is 1
% or more, a wear-resistant aluminum alloy for plastic working with excellent heat treatment properties. 2. 0.05% of one or more of Mn, Cr, and Zr
Claim 1 characterized in that it further contains more than 2% of
A wear-resistant aluminum alloy for plastic working with excellent heat treatment properties. 3. Abrasion resistance for plastic working with excellent heat treatment properties according to claim 1 or 2, further containing one or more of Pb, Sn, and Bi in an amount exceeding 0.1% and up to 3%. Aluminum alloy. 4. The wear-resistant aluminum alloy for plastic working with excellent heat treatment properties according to any one of claims 1 to 3, further comprising more than 0.5% and up to 3% Ni. 5. 0.00 of one or more of Na, Sr, and Sb
The wear-resistant aluminum alloy for plastic working with excellent heat treatment properties according to any one of claims 1 to 4, further comprising more than 1% and up to 0.5%. 6. The wear-resistant aluminum alloy for plastic working with excellent heat treatment properties according to any one of claims 1 to 5, further comprising more than 0.2% and up to 2% Fe.