JPS6227147B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a free-cutting aluminum alloy and a method for producing the same, and more particularly, the present invention relates to an aluminum alloy that has excellent machinability in an annealed soft state, and extruded materials such as aluminum alloy tubes and rods, or after extrusion,
The present invention relates to a method for producing an aluminum alloy that is used in an annealed soft state by performing plastic working such as drawing and forging. Conventionally, aluminum alloys with excellent machinability contained Cu as the main element, with small amounts of Pb and
The 2011 alloy containing Bi and the 6262 alloy containing Mg ₂ Si as a main component and small amounts of Pb and Bi are well known. However, all of these alloys are precipitation hardening alloys, and although they are aluminum alloys that have excellent machinability in the hardened state by quenching and tempering, the machinability is extremely poor in the soft annealed state. In addition, recently, non-heat-treated free-cutting alloys made of Al-Mg alloys containing small amounts of Pb and Sn have been put into practical use, but they have excellent machinability in some work-hardened state such as H16 or H34. However, like the precipitation hardening alloy described above, the machinability is extremely poor in the annealed soft state. When using these free-cutting aluminum alloys, in order to use them in a completely strain-relieved state, annealing and softening may be performed and then cutting, or cutting may be performed after strain-relieving intermediate annealing. Since the machinability of the free-cutting aluminum alloy is significantly deteriorated, there is a possibility that the use of the aluminum alloy will not be effective. In addition, aluminum alloys used for precision parts with particularly severe distortion and dimensional accuracy, such as camera interior cam tubes and copier rollers, are cut in a completely annealed and soft state to completely eliminate distortion. However, for such applications, it has relatively high strength in a completely soft state,
5052 is a non-heat treatable alloy with excellent corrosion resistance.
(Al-2.5wt%Mg-0.25wt%Cr) and 5056 (Al
-5.1wt%Mg-0.13wt%Cr-0.13wt%Mn) are used. However, these aluminum alloys have poor machinability in the fully annealed soft state, and the chips are completely continuous during cutting, making it difficult for machine tools,
Since chips tend to get entangled with tools and workpiece materials and need to be removed each time, automation is needed to reduce costs in the current situation where automatic cutting machines are often used.
Unmanned machining is extremely difficult, and furthermore, as mentioned above, any free-cutting aluminum alloy could not be used. The present invention solves the various problems in the conventionally used free-cutting aluminum alloys as described above, and provides a free-cutting aluminum alloy with excellent machinability, that is, excellent chip disposability in an annealed soft state, and the like. A manufacturing method is provided. The free-cutting aluminum alloy and its manufacturing method according to the present invention are as follows: (1) Mn0.3-1.7wt%, Fe1.5wt% or less, Pb0.2-1.5wt%, Sn0.1-2.0wt%, Si0.3wt % or less, Mg 0.7wt% or less, Ti 0.3wt% or less, B 0.1wt% or less, and Cu 6.0wt% or less, Zn 3.0wt% or less, Ni 3.0wt% or less, Cr 0.3wt% or less, An annealed soft state characterized by containing one or more selected from 0.3wt% or less of Zr, with the remainder substantially consisting of Al, and in which agglomerated spheroidal crystallized substances are uniformly dispersed. The first invention is a free-cutting aluminum alloy used in (2) Mn0.3-1.7wt%, Fe1.5wt% or less, Pb0.2-1.5wt%, Sn0.1-2.0wt%, Si0. Contains 3 wt% or less, Mg 0.7 wt% or less, Ti 0.3 wt% or less, B 0.1 wt% or less, and Cu 6.0 wt% or less, Zn 3.0 wt% or less, Ni 3.0 wt% or less, Cr 0.3 wt% or less , an aluminum alloy containing one or more selected from 0.3wt% or less of Zr, with the remainder substantially consisting of Al, is melted and cast, and this ingot is heated at 480 to 635℃.
Soak the ingot for 0.5 to 24 hours at a temperature of
Extruded at a temperature of 320~520℃, this extruded material is 80%
From two inventions whose second invention is a method for producing a free-cutting aluminum alloy used in an annealed soft state, characterized by uniformly dispersing agglomerated spheroidal crystallized substances by drawing at the following processing rate: It is what it is. In the free-cutting aluminum alloy and the method for producing the same according to the present invention, 1) free-cutting aluminum alloys are formed by containing Mn and Fe to form crystallized MnAl ₆ and (Mn・Fe)Al ₆ , as well as low-melting point metals such as Pb and Sn; 2) Furthermore, Cr, Zr,
By containing Ti, Ni, etc., the amount of crystallized substances is increased and free machinability is improved.3) And, Mn, Cu,
By containing Fe, Ti, Zn, Zr, Cr, Ni, etc., the strength of the annealed soft material is increased. 4) By heating the aluminum alloy ingot at high temperature, the crystallized material is agglomerated and spheroidized, and then by plastic working. It is based on these four things, such as uniformly dispersing these crystallized substances. A free-cutting aluminum alloy and a method for manufacturing the same according to the present invention will be explained in detail. First, the components and component ratios of the free-cutting aluminum alloy will be explained. Mn is an essential element for producing Al-Mn-based crystallized substances that provide free machinability, specifically, crystallized substances such as Al ₆ Mn or Al ₆ (Mn/Fe). This effect is poor when the content is less than 0.3wt%, and when the content exceeds 1.7wt%,
Huge Al-Mn-based compounds crystallize as primary crystals, shortening the life of tools, etc. and impairing surface finish and alumite properties. Therefore, the Mn content is set to 0.3 to 1.7 wt%. Fe is an element that helps generate Al-Mn-based crystals that give free machinability, and has the effect of facilitating the formation of Al ₆ (Mn Fe) crystals, making crystal grains finer, and improving strength. The higher the Fe content, the better.
If the content exceeds 1.5wt%, giant compounds tend to form, impairing tool life, surface finish, alumite properties, and corrosion resistance. Therefore, the Fe content is
The content shall be 1.5wt% or less. Pb and Sn have a great effect on improving machinability; less than 0.2wt% Pb and less than 0.1wt% Sn have no effect on improving machinability; Corrosion resistance at contents exceeding
Damages the alumite properties. Therefore, the Pb content is 0.2
~1.5wt%, Sn content is 0.1~2.0wt%. Note that if the elements Pb and Sn are contained alone, the effect of improving machinability will not be sufficient, but if both elements are contained at the same time, a further effect of improving machinability will be obtained. In order for the free-cutting aluminum alloy according to the present invention to exhibit excellent machinability, Si, Mg,
It is necessary to control the Mg content, and if the Si content exceeds 0.3wt%, α
Al ₆ Mn gives machinability by creating AlMnSi compound
As _a result of the inventor's intensive research, it was found that Mg is an extremely effective element for improving strength, but if the content is less than 0.7wt%, If the content exceeds this amount, Mg combines with Pb and Sn, which have a great effect on improving machinability, and forms compounds such as Mg ₂ Pb and Mg ₂ Sn, which significantly impairs machinability. Therefore, from the point of view of machinability, Si
Content is 0.3wt% or less and Mg content is 0.7wt
% or less. Ti and B have the effect of refining the crystal grains of the ingot or wrought material, uniformly dispersing crystallized substances or low melting point metals, and improving the surface finish.
If Ti and B exceed 0.3wt% and B0.1wt%, respectively, a huge intermetallic compound will crystallize between Al and the tool life will be shortened. Therefore, the Ti content is 0.3 wt% or less, and the B content is 0.1 wt% or less. Cu is an important element that improves strength, and the higher the Cu content, the more pronounced the effect of improving strength, but the more it impairs corrosion resistance, so it is better to decide the content based on the balance between these effects. If the content exceeds 6.0wt%, the extrudability will be significantly deteriorated. Therefore, the Cu content should be 6.0wt% or less. Zn is effective in improving machinability at high speeds and increasing strength, but if the content exceeds 3.0 wt%, corrosion resistance will be significantly impaired. Therefore, the Zn content should be 3.0wt% or less. Ni improves machinability by forming intermetallic compounds such as Al-Ni, Al-Cu-Ni, and Al-Fe-Ni.
If the content exceeds 3.0wt%, huge intermetallic compounds will crystallize, significantly impairing tool life, surface finish, alumite properties, and corrosion resistance. Therefore, the Ni content should be 3.0wt% or less. Cr and Zr form crystallized substances such as Al-Cr and Al-Zr to improve machinability, and are also effective in improving strength and preventing coarsening of recrystallized grains. If it exceeds 0.3wt%, huge intermetallic compounds will crystallize, impairing tool life, surface finish, alumite properties, and corrosion resistance. Afterwards,
The Cr content is regulated to 0.3wt% or less, and the Zr content is regulated to 0.3wt% or less. Next, a manufacturing method according to the present invention will be explained. In the free-cutting aluminum alloy according to the present invention,
It is important for crystallized substances to aggregate into spherules and to disperse uniformly in order to improve machinability, and for this purpose, it is necessary to soak the ingot at a higher temperature. In the manufacturing method according to
The soaking temperature is 480 to 635°C. If the soaking temperature is less than 480°C, the crystallized material will not be sufficiently agglomerated and spheroidized, and if it exceeds 635°C, the ingot will melt. Therefore, the soaking temperature is 480-635℃
shall be. If the soaking temperature is maintained for too short or too long, the soaking treatment will not be effective, so the soaking time is preferably in the range of 0.5 to 24 hours. The ingot that has been soaked in this way is extruded at a temperature of 320 to 520°C, but if it is less than 320°C, sufficient extrusion cannot be achieved, and although a high extrusion temperature is better for precipitation strengthening, it is not If the temperature is too high, baking will occur, so it is best not to perform the process at temperatures exceeding 520°C. Therefore, the extrusion temperature is 320 to 520°C. Next, drawing processing is performed at a processing rate of 80% or less to uniformly disperse the aggregated, spherical crystallized material. Examples of the free-cutting aluminum alloy and the manufacturing method thereof according to the present invention will be described. Example An aluminum alloy having the components and proportions shown in Table 1 was melted and cast according to the conventional method to form a 155mmφ
The ingot is homogenized for 4 hours at a temperature of 520 to 620℃, extruded at a temperature of 450 to 480℃ to form a round bar with a diameter of 50mmφ, and then cold drawn into a round bar with a diameter of 41mmφ. The rods were then completely annealed and softened at 450°C for 2 hours, and used as specimens for cutting tests and hardness tests. Table 2 shows the results of a comparison of machinability, hardness (measured using a Witzkers hardness meter), and surface condition of the cut surface. Cutting performance: using a carbide tool with a rake angle of 10° on an automatic lathe at peripheral speeds of 150 and 400 m/min, feed rate of 0.05~
Cutting was performed with a depth of cut of 2.0 mm using each combination of 0.2 mm/rev, and judgment was made based on the shape of the chips obtained. Figure 2 is a standard that shows the grade of chip shape. Figure 2a shows the case where the chip is finely divided and the machinability is the best, and as it approaches Figure 2e, the chip is not divided and The chips become continuous, and FIGS. 2 d and 2 e show a state in which the chips are continuous for a considerable distance and are difficult to cut in practice.

【table】

[Table] As is clear from Table 2, all the free-cutting aluminum alloys according to the present invention have extremely excellent machinability, and have hardness comparable to that of 5052 equivalent alloys.
It can be seen that the machinability is also extremely good. especially,
Excellent for high-speed cutting. Furthermore, as shown in Table 2, the manufacturing method according to the present invention shows very excellent machinability, especially when soaked at high temperatures. This is the first
As shown in the micrograph of the ingot structure of alloy No. 2 according to the present invention in Figure a, the free-cutting aluminum alloy produced by the manufacturing method according to the present invention is subjected to soaking treatment at a high temperature, resulting in agglomeration of crystallized substances and spheroidization. It can be uniformly dispersed by subsequent extrusion and drawing processes, which improves machinability.
Furthermore, Fig. 1b is a micrograph of the ingot structure of comparative alloy No. 11, and compared to the ingot structure in Fig. 1a, it is clear that the state of the crystallized substances is not agglomerated or spheroidized. Recognize. As explained above, since the free-cutting aluminum alloy and the manufacturing method thereof according to the present invention have the above-mentioned configuration, the strength is high in the annealed soft state.
It has the same level of machinability as 5052 alloy, and has extremely good machinability, making it useful for a wide range of applications such as optical parts that undergo a cutting process after annealing, copying machine rollers, and forging.

[Brief explanation of the drawing]

FIG. 1a is a micrograph of the ingot structure of a free-cutting aluminum alloy according to the present invention, FIG. 1b is a micrograph of the ingot structure of a comparative alloy, and FIG. 2 is a schematic diagram showing the grade of chip shape. .

Claims (1)

[Claims] 1 Mn0.3-1.7wt%, Fe1.5wt% or less, Pb0.2-1.5wt%, Sn0.1-2.0wt%, Si0.3wt% or less, Mg0.7wt% or less, Ti0 .3wt% or less, B0.1wt% or less, and selected from Cu6.0wt% or less, Zn3.0wt% or less, Ni3.0wt% or less, Cr0.3wt% or less, Zr0.3wt% or less 1. A free-cutting aluminum alloy used in an annealed soft state, which contains one or more kinds of aluminum, the remainder substantially consists of Al, and has uniformly dispersed agglomerated spheroidal crystallized substances. 2 Mn0.3-1.7wt%, Fe1.5wt% or less, Pb0.2-1.5wt%, Sn0.1-2.0wt%, Si0.3wt% or less, Mg0.7wt% or less, Ti0.3wt% or less, B0 .1wt% or less, and one or more types selected from Cu6.0wt% or less, Zn3.0wt% or less, Ni3.0wt% or less, Cr0.3wt% or less, Zr0.3wt% or less An aluminum alloy containing aluminum with the remainder substantially consisting of Al is melted and cast, the ingot is soaked at a temperature of 480 to 635°C for 0.5 to 24 hours, and the soaked ingot is heated to a temperature of 320 to 635°C.
A free-cutting aluminum alloy used in an annealed soft state characterized by extrusion at a temperature of 520°C and drawing processing of this extruded material at a processing rate of 80% or less to uniformly disperse agglomerated and spherical crystallized substances. Production method.