JPS61166938A - Al-li alloy for expansion and its production - Google Patents

Abstract

PURPOSE:To obtain Al-Li alloy having low density and high elasticity, superior mechanical properties such as strength, ductility, and toughness by incorporating prescribed percentage of >=1 element among Zr, Cr, Mn, V, and Ti to the Al-Li alloy having a specific composition. CONSTITUTION:The alloy consists of, by weight, 1.5-3.0% Li, 0.5-3.0% Cu, 0.5-3.0% Mg, and >=1 kind among 0.05-0.3% Zr, 0.05-0.3% Cr, 0.05-1.5% Mn, 0.05-0.3% V, and 0.005-0.1% Ti, and the balance Al, and satisfies 3<=Cu+2Mg<=8, if necessary. The above alloy ingot is subjected to homogenizing heat treatment at about 400-550 deg.C for about 2-50hr, to hot working at >=about 300 deg.C, and to cold working if necessary, followed by solution heat treatment and aging to obtain the desired alloy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] The present invention relates to an Al-Li alloy for wrought use and a method for producing the same, and more specifically, to a high-rigidity, low-density AI-Li alloy with excellent ductility and toughness. This invention relates to alloys and their manufacturing methods.

[Prior Art 1 Generally, when AI contains Li, the density decreases by about 3% and the elastic modulus increases by about 6%.
Alloys can now be made lighter than conventional Al alloys, and currently, Al alloys containing 2 to 3 d% Ll are being considered for practical use as structural materials for aircraft, etc., which have a large weight reduction effect. There is.

Utilizing the above-mentioned properties of Al-Li alloys, we are also considering practical use in a wide range of applications, including structural materials for linear motor cars, various sports equipment such as tennis rackets, and speaker diaphragms. has been done.

In this way, in order for Al-Li alloys to be widely used, it is necessary to achieve lower density and higher elasticity.
It is essential to have material properties such as strength and toughness that are equivalent to or better than conventional Al alloys.

However, since the density and elastic modulus of Al-Li alloys are physical properties, they are not affected much by the manufacturing method, but are largely influenced by the Li content contained in Al. The low density and high elasticity of the steel are mainly determined by the amount of Li contained.

However, the Li content has its own limit, and Ll
If the content is too large, the strength will be saturated, the elongation and other ductility will be significantly lowered, and the elongation will be less than 1%, making it unsuitable for practical use.

Therefore, what is important in Al-Li alloys is that L
The goal is to contain as much Al-L as possible to achieve low density and high elasticity, and to obtain excellent material properties.
The biggest problem with the properties of i-series alloys is that their ductility and toughness are poor in comparison to the strength they provide.

[Problem to be Solved by the Invention 1] The present invention has been made based on the research on the properties of Al-Li alloys as explained above and the knowledge of the results. The present invention provides a high-rigidity, low-density AI-based alloy that has excellent mechanical properties such as strength, ductility, and toughness, and a method for producing the same.

[Means for Solving the Problems 1] The method for producing Al-Li construction plans for scrap elongation according to the present invention is as follows: (1) Li 1.5 to 3.0 wt%, Cu 0.5
~3.0wt%, M'g 0.5~3.0u+t%, and Zr 0.05~0.3u+t%, Cr 0.05~0
．． 3u+t%, Mn 0.05-1.5llt%, V
0.05-01wt%, Ti 0.005-0.00
A first Al-Li based alloy for drawing is characterized in that it contains one or more selected from 5 to 0.1 wt%, and the balance consists of Al and unavoidable impurities.
(2) Li 1.5 to 3.0 wt%, Cu 0.5
~3, Contains Ou+L%, Mg 0.5-3.0wt%, and 3u+t%≦Cu+2Mg≦8%, and furthermore, Zr 0.05-0.3wt%, Cr 0.05-0 ．．
3u+t%, Mn 0.05-1.5wt%, V 00
05~0.3+nt%, Ti 0.005~0.1wt
A second invention provides an Al-Li alloy for wrought use, which contains one or more selected from the following: (3) Li 1. 5-3.0+ut%, Cu 0.
5-3.0 wt%, Mg0.5-3.0t+1%, and Zr 0.05-0.3 wt%, Cr 0.05-0.
3wt%, Mn 0.05-1.5wt%, V 0.0
5 to 0.3 wt%, Ti 0.005 to 0.1 wt%, and the remainder consists of Al and inevitable impurities.
The Li-based alloy ingot was heated at a temperature of 400 to 550°C for 2 to 5 minutes.
A method for producing an AI Li-based alloy for wrought use, in which the vf characteristic is homogenization heat treatment for 0 hours, then hot working at a temperature of 300 ° C. or higher, and then solution treatment and aging treatment. As the third invention, (4) Li 1.5
~3,0wt%, Cu 0.5~3,0wt%, Mg0
．． 5 to 3.0 wt%, and Zr 0.05 to 0.3 wt%, Cr 0.05 to 0.
3u+L%, Mn 0.05-1.5wt%, \
'0.05~0.3uL%, Ti 0.005~
Al-
A Li-based alloy ingot is heated at a temperature of 400 to 550°C for 2 to 50°C.
A method for expanding Al- A method for producing a Li-based alloy as a fourth invention 4
This invention consists of two inventions.

EMBODIMENT OF THE INVENTION Hereinafter, the Al-Li alloy for drawing and the manufacturing method thereof according to the present invention will be explained in detail.

First, the components and component ratios of the AI Li alloy for wrought according to the present invention will be explained.

Li is an essential element for improving strength, low density and high elasticity. If the content is less than 1.5 wt%, the low density and high elastic modulus are too small, and 3.0 wt% If the content exceeds 100%, the strength will be saturated, and furthermore, the ductility and toughness will be significantly reduced.

Therefore, the Li content is set to 1.5 to 3.0 wt%.

Cu is an essential element for improving strength, and if the content is less than 0.5 u + t%, strength will be insufficient, and if the content exceeds 3.0 wt%, ductility and toughness will decrease. It is also disadvantageous for density.

Therefore, the Cu content is 0.5 to 3. Let it be OuL%.

Mg is an element that improves strength without reducing ductility and toughness; if the content is less than 0.5u+t%, the strength will not improve much, and if the content exceeds 3.0wt%, the ductility and toughness will decrease. descend. Therefore, the Mg content is set to 0.5 to 3.0 wt%.

In addition, Cu and M for Li 1.5 to 3.0 wt%
When the g content is Cu+2Mg<3uL%, sufficient strength of the final product cannot be obtained, and when Cu+2Mg≧8wt%
In this case, the amount of crystallized substances such as CuLiAl□ (T, phase) and CuMgAl2 (S phase) increases, and the elongation and toughness of the final product are significantly reduced. Therefore, the content of Cu and Mg is
3u+L%≦Cu+2Mg≦8wL%.

Zr, Mn, Cr, and V are used to make l/w (I is the length of the elongated grain in the rolling direction, and the butt is the thickness of the elongated grain in the plate thickness direction) to be 20 or more in the microstructure after the final heat treatment. It is a necessary element, and the content of Zr, Mn, Cr, ■ is 0.0
If it is less than 5 wt%, the microstructure becomes large in the final heat treatment and recrystallization starts and 1/w<20, and Z
r 0.3u1%, Mn1.5wt%, Cr 0.31
If the content exceeds wt% and V OJwL%, the effect will be saturated, and further content will be wasteful. Therefore, Zr
Content 0.05-0.3+ut%, Mn content 0.0
5~1.5u+t%, Cr content is 0.05~0.3w
t%, ■ Content is 0.05 to 0.3u+t%.

Ti is an essential element for making the macrostructure of the ingot fine, and if the content is less than 0.005+ut%, this effect cannot be achieved, and if the content exceeds 0.11%, it will not be possible to achieve this effect. If this happens, the amount of crystallized substances will increase and the ductility and toughness will deteriorate. Therefore, the T1 content is 0.005 to 0.1
IIlt%. Note that Ti may be used alone or Ti and B may coexist.

Furthermore, if the content of Fe and Si contained as impurities in the ingot exceeds 0.25 wt%, Al-Fe-3i
Systemic crystallization increases and the ductility, toughness and fatigue properties of the final product are significantly reduced. Therefore, Fe or Si is 0.2
It needs to be 5 wt% or less.

Next, a method for producing an Al-Li alloy for wrought according to the present invention will be explained.

An Al-Li alloy ingot having the above-mentioned components and component ratios is formed so that the crystal grain size of the ingot is as fine as possible, for example, 3 mm or less. When the crystal grain size of this ingot is 3mL11 or more, CuzFeAl7, Cu, Li2A1.5 (T phase), C existing at the grain boundaries
uL iA 12 (TI phase), CuLi-Al6 (T
Since the size and distribution of crystallized substances such as 2-phase) become coarse and non-uniform, the elongation and toughness of the final product deteriorate.

Next, the ingot is heated to a temperature of 400 to 550'C for 2 to 5 minutes.
Homogenization heat treatment is carried out for 0 hours, but this homogenization heat treatment is carried out in such a way that (1) non-uniformly distributed elements such as Li, Cu, Mg, etc. are dissolved in the matrix, and the above-mentioned crystallized substances are partially dissolved; (2) Zr, Cr, Mn
, ■ transition elements are Al, Mg and ZrAl. ,CrzMg
Precipitates (dispersoids) of intermetallic compounds such as y A l + s, MnAl6, VA+6 are formed. These (1) and (2) are the purpose of homogenization heat treatment, the homogenization heat treatment temperature is less than 400℃, and the homogenization heat treatment time is 2.
If the homogenization heat treatment temperature exceeds 550'C1 and the homogenization heat treatment time exceeds 50 hours, the above objectives (1) and (2>) cannot be achieved. The precipitation state becomes coarse and non-uniform, making it impossible to form the desired unrecrystallized structure or fine elongated branches in the final product.Therefore, the homogenization heat treatment
It is carried out for 2 to 50 hours at a temperature of 'C. In addition, this homogenization heat treatment is applied to precipitates (crispersoi).
In order to make the precipitation state of ds) fine and uniform, the first half was
The treatment may be carried out at a low temperature of 0 to 480°C, and the second half may be carried out at a high temperature of 480 to 550°C for homogenization and solid solution of crystallized substances to shorten the treatment time and improve performance.

After this homogenization heat treatment, it is rolled at a temperature of 300°C and hot worked by extrusion or forging.
At temperatures below 0°C, when the product is subjected to final heat treatment (for example, T6 heat treatment), the shape ratio of elongated grains excluding subgrains in the microstructure becomes l/w (20), resulting in a decrease in ductility; In order to eliminate the occurrence of cracks and the like during this hot working, the starting temperature of hot working is preferably 400°C or higher.

For plates, extrusions, and forged materials whose final product has a thickness of approximately 3II11 or more, the processing before solution treatment is completed in the above process.6 However, for those whose final product has a thickness of approximately 3ml11 or less, Cold-opening processing such as cold-opening rolling is performed.

In this cold working, the final cold working rate is 70% or less, and if this cold opening rate is higher than 70%, the shape ratio of elongated grains in the microstructure after the final heat treatment becomes l/+u < 20, which is undesirable. , this cold working rate is based on soaking treatment conditions,
AI for stretching according to the present invention whose hot working temperature is as explained above
Outside the range in the Li alloy manufacturing method, 40~
The cold working rate must be 50% or less, which is disadvantageous in manufacturing because the cold working rate cannot be increased.
0% can only be achieved by limiting the soaking treatment conditions and hot working temperature as explained above.

In order to impart a predetermined strength to the product manufactured by the above hot working or cold working, the product is solution-treated and then hardened, and if necessary, cold-opened and then subjected to an aging treatment.

In addition, in the above explanation, the shape ratio of elongated grains excluding subgrains in the microstructure is 1/w (l is the length of elongated grains in the rolling direction,
The reason for setting the elongated grain thickness (thickness of elongated grains in the sheet thickness direction) to 20 or more has been shown, but to explain further, Al-Li alloys are extremely prone to intergranular fracture, and this causes a decrease in ductility and This is the biggest cause of decreasing toughness, and the shape ratio of elongated grains excluding subgrains in the microstructure is 17w<20.
If the cracks are not elongated very much, the cracks will easily pass through the grain boundaries, resulting in near-universal intergranular fracture and reduced ductility and toughness. Shape ratio of elongated grains excluded is 17w>20
If the crack is elongated and elongated, the propagation path of the crack becomes long, and if the propagation path becomes too long, it becomes more advantageous to proceed inside the grain, which reduces the rate of intergranular fracture.
Improves ductility and toughness.

[Example 1] An example of an Al-Li alloy for drawing and a method for producing the same according to the present invention will be described.

Example 1 An aluminum alloy having the components and proportions shown in Table 1 was melted and cast to produce an ingot with a thickness of 315 cm.

Next, homogenization heat treatment → hot rolling → intermediate annealing → cold rolling was performed under the manufacturing processing conditions shown in Table 2, and 1,5 n+
We produced rolled materials of 3 cities.

This rolled material was subjected to solution treatment at 520°C for 30 minutes,
It was immediately quenched in water at room temperature, then tensile straightened by 2% to remove quenching distortion, and aged at 190°C for 16 hours.

The crystal grain shapes are shown in Table 2, and the material properties are shown in Table 3.

As is clear from Tables 2 and 3, the Al-Li alloy for wrought use and the manufacturing method thereof according to the present invention have superior material structure and fi-mechanical properties compared to the comparative alloys and comparative methods. It can be seen that it has certain characteristics.

[Effect of the invention 1 As explained above, since the AlLi-based alloy for wrought use and the method for manufacturing the same according to the present invention have the above configuration, it is possible to achieve a low density and a high elastic modulus. Furthermore, it has high strength and excellent ductility and toughness.

Claims (4)

[Claims] (1) Li1.5-3.0wt%, Cu0.5-3.0
wt%, Mg0.5-3.0wt%, and Zr0.05-0.3wt%, Cr0.05-0.3w
t%, Mn0.05-1.5wt%, V0.05-0.
3 wt% of Ti, 0.005 to 0.1 wt% of Ti, and one or more selected from the group consisting of Al and inevitable impurities. (2) Li1.5-3.0wt%, Cu0.5-3.0
wt%, Mg0.5-3.0wt%, and 3wt%≦Cu+2Mg≦8wt%, and further contains Zr0.05-0.3wt%, Cr0.05-0.3w
t%, Mn0.05-1.5wt%, V0.05-0.
3 wt% of Ti, 0.005 to 0.1 wt% of Ti, and one or more selected from the group consisting of Al and inevitable impurities. (3) Li1.5-3.0wt%, Cu0.5-3.0
wt%, Mg0.5-3.0wt%, and Zr0.05-0.3wt%, Cr0.05-0.3w
t%, Mn0.05-1.5wt%, V0.05-0.
Al-
A Li-based alloy ingot is heated at a temperature of 400 to 550°C for 2 to 50°C.
1. A method for producing an Al-Li alloy for wrought use, which comprises subjecting it to homogenization heat treatment for a long time, followed by hot working at a temperature of 300° C. or higher, followed by solution treatment and aging treatment. (4) Li1.5-3.0wt%, Cu0.5-3.0
wt%, Mg0.5-3.0wt%, and Zr0.05-0.3wt%, Cr0.05-0.3w
t%, Mn0.05-1.5wt%, V0.05-0.
Al-
A Li-based alloy ingot is heated at a temperature of 400 to 550°C for 2 to 50°C.
A method for expanding Al- A method for producing a Li-based alloy.