JPH02270929A - Aluminum alloy extruded material having less spring back and its manufacture - Google Patents

Abstract

PURPOSE:To obtain the extruded material having high strength and less spring back as extruded by subjecting an Al-Mn base Al alloy having specified compsn. to specified homogenizing treatment and forming its structure into the one in which specified precipitates are present. CONSTITUTION:An ingot of an Al-Mn base alloy contg., by weight, 0.8 to 2% Mn, contg. one or more kinds among Cr, Cu, Ti, B and Mg in the proportion of 0.02 to 0.1% Cr, <=0.2% Cu, 0.005 to 0.5% Ti, 0.0005 to 0.06% B and <=1% Mg, furthermore contg., as impurities, <=0.7% Fe, <=0.6% Si, <=0.1% Zn, <=0.05% Zr and <=0.05% V and the balance Al is used. The ingot is heated at 550 to 640 deg.C for <=1hr, is thereafter cooled to 420 to 540 deg.C at <=20 deg.C/hr cooling rate and is subjected to hot extruding at 420 to 540 deg.C starting temp. to let acicular or bar-shaped precipitates of >=0.2mu length exist in the alloy in the ratio of >=5 pieces/10<-2>mm<2>.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to an aluminum alloy extruded material with a small amount of springback and a method for manufacturing the same, and more specifically, the amount of springback obtained by bending as extruded or after extrusion and annealing. The present invention relates to a small Al1-Mn-based aluminum alloy extruded material and a method for producing the same.

[Prior Art] A11. used for heavy duty parts and other uses.
-Mn-based aluminum alloy extruded materials are subjected to 044 treatment after extrusion (to reduce the amount of springback) in order to increase the dimensional accuracy after being subjected to bending, etc., and their chemical components are adjusted.

Conventionally, 3003-0 material has been mainly used as such AA-Mn-based aluminum extruded materials, and pure AM has been used for materials that require high dimensional accuracy.

However, in recent years, the shapes of products have become more complex, and there has been a strong demand for extruded materials of -Mn-based aluminum alloys that have high strength and a small amount of springback after bending. However, 1. The conventionally proposed A℃-M
It will be difficult to deal with this problem with n-based alloy extruded materials and their manufacturing methods.

[Problems to be Solved by the Invention] The present invention has the following advantages: 1. Spring back after processing is small in each process including bending. And the strength is high, Blingba J? A small aluminum alloy extrusion and its manufacturing method are marketed for the purpose of #2 production.

[F stage for solving the problem] The first gist of the present invention is that Mr+: 0.8-2 zero (W
(same as below), h-t,, exposed', Cr, Cu
, Ti, B, Mro at least one of %C
r: 0.02 xo, 1'4. Cu: 0°2 zero or less,
Ti: 0.005-0.5%, Boo. 00f+5'
! Contains ~0° [16%i, Vlg: 1 in the following proportions, and further contains impurities and Fe: 0.7%i
fJ lower, Si: 0.6 p or less, 2r+: 0. tk or less, 7. r: 0.05! In the above, V: 0.05 digits, and the remainder is actually 72゛ consisting of A2 -Mn
It is a base alloy, and there are 5 or more nail-shaped or rod-shaped particles/10-2 mm2 with a length of 0□2 μm or more when put together and inside. There are extruded aluminum alloys that are characterized by a small amount of springback.

The second gist of the present invention is that it contains Mn+0.8...False2, and further contains Cr, Cu, T1. B, at least one of Mg, C1.: 0.02 ~ 0
．． 1 zero, (:u:0.2111+ below, 1
10.005~0.5λ, B:0.0005~0.0
6%, J: Contains at a ratio of 1 or less, and Fe<0.7%. If St<0.61, then
The unavoidable impurities are set to 0° or less, and the remainder consists of A, 17 in terms of actual N. 11-Mn base gold ingot, 1j50
= 1 llr or more at a temperature of -640°C]: After heating, 20t,
/Hr less than 100℃ to 400 □ Cooling to 550℃ with 1 h missing (to 1420・starting temperature of 540℃ 1,
: Hot extruded with t) and placed in a metal-containing medium until the length is 0.
Nail-shaped or rod-shaped precipitates of 21 mm or more! ；Pcs／' 10 ” '田 j−more existi j: t ′?:)
A method for producing aluminum extruded ram alloy with a small springback amount characterized by two holes as shown in Fig. 11. Reason for Limiting Ingredients) First, the components and component ratios of the aluminum alloy extruded material of the subsono debugging material according to the present invention will be explained.

! h+: 0.75-2 When Mn is added to Song Aβ, processing↑1, jl resistance is reduced; roughness is reduced, but strength is improved. 0□75* Endorrhea T・
If there is, the strength is low and the amount of nail-shaped precipitates is small;
If it exceeds 64, the amount of S1-like precipitates increases, and the effect of reducing the crystal grain size is saturated, but the amount of springback increases. Therefore, M + terrible f ball into l is 0.
Let it be 75x2 zero.

Cr, Cu, Ti, B, and Mg all have the effect of reducing the amount of subsonic bulk.

Cu: 0.2 1. lJ, -1:"Cu has the effect of increasing the strength (1-1).
, :l, the resistance fk +Il of t) becomes low 7,
Also, the amount of horns becomes weaker. , ＋,
, , , y・ is), (: 1.+ addition ヱ is 0,2
Must be smaller than a palanquin. 1C1・003−・0.1% Cr easily reduces the loss of rod-shaped precipitates. Below 0.03, the effect of −τ is small, and 0.
．． 1 zero = 5 =: 1χ The springback increases. 1, and the addition of C' is 0903 to 0.1 hole.

1'i: O, n05 zo, 5N Ti is used t) to refine the crystal grains of the ingot. If it is less than 0.005X, there is no effect, and if it exceeds 0.5*, where the amount of springback does not decrease, the effect will not change. Therefore, Ti is 0.005~0°5
Let it be t.

B: 0.0O05 zero to 0.0δ zero B refines the crystal grains of the ingot. It is preferable to use it together with Ti because it mainly refines the crystal grains of the ingot due to the mutual effect with Ti. If it is less than o, ooo bond, there is no effect.
Also, the amount of springback does not decrease. When the value exceeds On, the effect is saturated. Therefore, B is o, o
oos zero to 0.06 zero.

In addition, Ti and B are A1-Ti, A4-B and A! -It can be contained as an intermediate alloy of Ti-B.

Mg: 1 zero or less Mg increases the strength as the amount added increases, but when it exceeds 1 zero, the amount of springback increases. Therefore, Mg addition should be 19 g or less.

Elements other than the above are treated as unavoidable impurities, and Fe is 0.
．． Less than 796, Sl less than 0.6 zero, 2n 0.1
Zero or less, Zr, V should be 0.0 or less. If these ranges are exceeded, the amount of springback increases.

(Regarding the structure) It has been found that the shape and number of precipitates in the ingot immediately before hot extrusion affect the springback of the product after extrusion. If the shape of the precipitate is spherical, the springback will increase. The present inventors have found that rod-shaped or needle-shaped precipitates that meet specific conditions are effective in reducing springback.

That is, it has been found that the presence of acicular or rod-shaped precipitates with a length of 0.2 μm or more at 5/10-'ff1m or more has the effect of reducing springback.

Even if a precipitate with a length of less than 0.2 μm exists, the effect of reducing springback is small, and it is preferable to make the precipitate as long as possible. Further, even if the length is 0.2 μm or more, (length)/(width) is preferably 1 or more. The number of such needle-shaped or rod-shaped precipitates is 5/10-2m+o
' or more. If the number is less than 5 pieces/10''2 m 112, the springback will be large.

(Regarding manufacturing conditions) The alloy according to the present invention is manufactured by the following steps: melting, agglomeration, hot extrusion, and cooling.

The present invention has found unique conditions regarding the homogenization treatment conditions in the above process and the subsequent hot extrusion temperature.

The conditions are as follows.

B. The slow rate of heating up the ingot to the homogenization treatment temperature has no particular effect.

The higher the homogenization temperature, the more the JZ-un system precipitates, the smaller the amount of springback, and the smaller the crystal grains of the product. The effect is small below 550°C, and the effect of the present invention occurs above sso t. However, when the temperature exceeds 640 t, burning of the alloy occurs.

C. The longer the homogenization treatment time, the greater the effect. The effect is small if it is less than 1 hour, and the effect becomes greater as the time exceeds 1 hour.

2. Extrusion start temperature after homogenization treatment (420-540°C)
The higher the cooling temperature, the greater the springback. When the temperature exceeds 20°C/)Ir, springback increases. Therefore, considering productivity, 20℃/
The optimum setting may be made within Hr or less.

E) The hot extrusion temperature following the homogenization process has an effect on productivity and springback. If it is less than 420°C, springback will be large and productivity will be poor; if it exceeds 540°C, springback will be large and surface quality will deteriorate.

To ensure hot extrusion speed, hot extrusion end temperature, cooling rate of the product after hot extrusion, and product dimensional accuracy, stretch processing, cold drawing, and subsequent annealing may be performed, but these conditions Regarding this, it may be within the range normally practiced industrially.

G. After homogenization treatment (550-640°C XI hr or more), the extrusion start temperature (420-540°C) is maintained at 20°C/Hr or less, and the productivity is better if extrusion is performed immediately after extrusion.
When hot extrusion cannot be performed immediately, hot extrusion may be performed after holding for a desired time (preferably 12 hours or less) 420 to 540 t. Alternatively, the temperature may be lowered to -degree room temperature and then heated again to the hot extrusion temperature (420 to 540 t).

Therefore, the manufacturing conditions are such that the ingot is heated at 550 to 830 tX
Homogenize for 1 hour or more, hot extrusion temperature (420-540
℃), cooled at 20℃/Hr or less, and extruded.
The subsequent conditions are preferably normal industrial production conditions.

[Example] Next, an example of the ^11-Mn-based aluminum alloy for extrusion and the manufacturing method according to the present invention will be described.

(Example 1) Typical components and component ratios of the n-Mn aluminum alloy for extrusion according to the present invention are shown in Table 1.

The alloys shown in Table 1 were melted, billet-peeled and sold at 600°C, then cooled to 440°C.
up to 5℃/hr) - Hot extrusion (starting at 440℃) -
After cooling and adjusting to room temperature, samples were prepared and the amount of springback and tensile strength were investigated. The results are shown in Table 2.

Note that the amount of springback was measured by the method shown in FIG.

The following can be seen from Table 2.

■The comparison material has a poor balance between the amount of springback and tensile strength, but the material of the present invention has a good balance, and the springback is small, especially when it comes to strong bending.

(Example 2) Sample No. 3 (without Cr addition) and No. 3 shown in Table 1
Table 3 shows the results obtained regarding the effect of manufacturing conditions (homogenization treatment, cooling rate after homogenization treatment to extrusion temperature, extrusion temperature) using 7 (Cr addition 0.03N).

The number of precipitates present was evaluated by taking an image with an optical microscope at 1000 times magnification and counting the number in an area of 73×951111n.

The following can be seen from Table 3.

(2) Even if there are a large number of needle-like or rod-like precipitates with a length of 0.1 μm (to the extent that they are difficult to count), the amount of springback will not become small.

(2) Even if needle-like or rod-like precipitates with a length of 8 μm are present, if the number is about three, the amount of springback will be large.

■The springback amount of the product of the present invention is smaller than that of the product under conventional manufacturing conditions.

(2) Regarding the addition of Cr, even under the same manufacturing conditions, the amount of precipitates is larger and the amount of springback is smaller than when Cr is not added.

[Effect of the invention] ゛As explained above, according to the present invention, a predetermined i-M
Since the n group is subjected to a specific homogenization treatment to have a structure in which specific precipitates are present, the crystal grains can be kept small and the amount of springback can be reduced even after extrusion.

Therefore, when used or designed for bending or press forming, no special treatment is required compared to conventional materials.

[Brief explanation of drawings]

FIG. 1 is a procedure diagram showing a method for measuring the amount of springback. No. T, P, -rimoe〉(5c knee 1=;=“xto
cmJ

Claims (2)

[Claims] (1) Contains Mn: 0.8 to 2% (same below wt%), and further contains at least one of Cr, Cu, Ti, B, and Mg, Cr: 0.02 to 0.1% ,Cu:0.2
% or less, Ti: 0.005-0.5%, B: 0.000
Contains 5% to 0.06%, Mg: 1% or less, and further contains Fe: 0.7% or less, Si: 0 as impurities.
．． 6% or less, Zn: 0.1% or less, Zr: 0.05% or less, V: 0.05% or less, and the balance is substantially Al. An aluminum alloy extruded material with a small amount of springback, characterized by the presence of acicular or rod-shaped precipitates with a length of 0.2 μm or more at a rate of 5/10^-^2 mm^2 or more. (2) Contains Mn: 0.8 to 2%, and further contains Cr, C
At least one of u, Ti, B, Mg, Cr:
0.02-0.1%, Cu: 0.2% or less, Ti: 0.
005-0.5%, B: 0.0005-0.06%, M
g: Contains at a ratio of 1% or less, further Fe<0.7%,
After heating an Al-Mn-based alloy ingot with Si<0.6%, unavoidable impurities being 0.2% or less, and the remainder substantially consisting of Al at a temperature of 550 to 640°C for 1 hour or more,
The alloy is cooled to 420-540°C at a cooling rate of 20°C/Hr or less, and then hot extruded at a starting temperature of 420-540°C to form a needle-like or rod-like material with a length of 0.2 μm or more. A method for producing an aluminum alloy extruded material with a small amount of springback, characterized in that the number of precipitates is 5/10^-^2 mm^2 or more.