Eureka AIR delivers breakthrough ideas for toughest innovation challenges, trusted by R&D personnel around the world.

Shock absorbing material

a technology of shock absorption and material, applied in the direction of bumpers, magnetic bodies, machines/engines, etc., can solve the problems of difficult reduction of the thickness of the cross sectional shape, poor accuracy, and difference in the cooling rate along the cross section

Inactive Publication Date: 2003-11-06
KOBE STEEL LTD
View PDF0 Cites 15 Cited by
  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0012] In view of the above, it is a second object of the present invention to provide an Al--Mg--Si series aluminum alloy extrusion material having high strength (yield stress) with excellent cracking resistance in the axial direction and energy absorbing property and, at the same time, excellent cracking resistance also in the lateral direction.
[0013] The present inventors have found an alloy composition and a structure having high strength (yield stress) and showing excellent energy characteristics when compressed in the axial direction of extrusion (showing high energy absorption with no occurrence of cracks) for the shock absorbing material of an Al--Mg--Si series aluminum alloy based on the premise of adopting press quenching under air cooling, which is advantageous in view of the dimensional accuracy and the cost.
[0017] On the contrary, the present inventors have found that Al--Mg--Si series aluminum alloy extrusion materials tend to cause cracks if the macrostructure thereof mainly comprises a recrystallization structure but occurrence of such cracks can be suppressed even at a high strength if it mainly comprises a fibrous structure (in a state where the fibrous structure after extrusion is left as it is with no recrystallization also during a heat treatment step subsequent to the extrusion step). On the other hand, it has also been found that the fibrous structure is loosened when the solution quenching treatment is applied in off-line and that formation of a surface recrystallization layer to a certain thickness is advantageous in order to obtain required characteristics by on-line press quenching.

Problems solved by technology

However, this results in a difference in the cooling rate along the cross section due to the difference of the cross sectional shape or the wall thickness of the extrusion materials, and makes the temperature distribution not uniform during cooling to cause distortion.
Accordingly, it results in problems that the accuracy is poor, thickness for the cross sectional shape is difficult to be reduced and the degree of freedom for the cross sectional shape is restricted if it is intended to prevent occurrence of such distortion.
There is also an additional problem that it requires higher cost compared with that in air-cooling.
However, since the cooling rate is limited, it results in a problem that no high strength (particularly, yield stress) can be obtained depending on the alloy compositions and, even when a high strength can be obtained, the energy absorption or the cracking resistance is poor.
Further, Al--Mg--Si series aluminum alloy extrusion materials involve a worry that spontaneous aging progresses to deteriorate the cracking resistance when exposed at a high temperature during use thereof, for example, as side members.
However, when strength is improved by T5, T6 treatment, it involves a problem of causing cracks when subjected to axial compressive deformation.
If cracks should occur, shrinking deformation in the bellows-form is inhibited failing to obtain stable energy absorption.
Further, the quenching sensitivity is generally increased as the amount of the additive elements increases and the amount of the precipitates at the boundaries also increases at a low cooling rate (for example, in air cooled press quenching which is advantageous in view of the dimensional accuracy or the cost), tending to cause cracks when crushed under large impact loads.

Method used

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View more

Image

Smart Image Click on the blue labels to locate them in the text.
Viewing Examples
Smart Image
  • Shock absorbing material
  • Shock absorbing material
  • Shock absorbing material

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0070] Al--Mg--Si series aluminum alloy billets of the chemical compositions shown in FIG. 1-1 were manufactured by melting by DC casting, and applied with a soaking treatment at 550.degree. C. .times.4 hr. Successively, by conducting extrusion under the conditions of an extrusion temperature at 500.degree. C. and an extrusion rate of 5 m / min, and press quenching (blower air cooling (cooling rate: about 190.degree. C. / min)) at the position just after the extrusion to obtain an extrusion material of a hollow cross section as shown in FIG. 1 (70 mm for longer side, 50 mm for shorter side and 2 mm for thickness). Then, the extrusion material was applied with an aging treatment at 190.degree. C. .times.3 hr to prepare test specimens. The thickness of the recrystallization layer from the outer surface and the inner surface at the central portion of the longer side and the shorter side for the cross section of the test specimen was measured to determine the thickness as an average value f...

example 2

[0075] Al--Mg--Si series aluminum alloy billets of the chemical compositions shown in Table 2-1 were manufactured by melting by DC casting and applied with a soaking treatment at 550.degree. C. .times.4 hr. Successively, extrusion was conducted at an extruding temperature of 500.degree. C. and at a extruding rate shown in Table 1, and air cooled or water cooled press quenching in on-line was applied just after extrusion to obtain extrusion materials each of a hollow rectangular cross section as shown in FIG. 4 (having 70-80 mm long or side, 54-60 mm shorter side and 2-5 mm thickness). Air cooling was applied by a blower air cooling at a cooling rate of about 190.degree. C. / min, whereas water cooling was applied at a cooling rate of about 10000.degree. C. / min. Then, an aging treatment at 190.degree. C. for 3 hours was applied to the extrusion materials to obtain test materials.

[0076] For the test materials, thickness of the surface recrystallization layer (GG layer), crystal grain si...

example 3

[0090] The example of the present invention is to be explained in comparison with a comparative example out of the definition for the scope of the claims of the present invention.

[0091] At first, Al--Mg--Si series aluminum alloy billets (diameter: 155 mm) of the chemical composition shown in the following Table 3-1 were manufactured by melting by the usual method and a homogenizing treatment was applied under the condition of about 540.degree. C..times.4 hours.

[0092] Then, each of the billets was subjected to extrusion under the conditions at an extrusion temperature of 500.degree. C. and an extrusion rate of 5 m / min, air cooled or water cooled press quenching was conducted on-line just after extrusion to manufacture extrusion materials each of hollow square cross section as shown in FIG. 4-(1) (a square pipe having an outer shape of 70.times.54 mm and a thickness of 2 mm). An artificial aging treatment was applied under the conditions shown in Table 3-1 to prepare test materials.

5 ...

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

PUM

PropertyMeasurementUnit
yield stressaaaaaaaaaa
yield stressaaaaaaaaaa
thicknessaaaaaaaaaa
Login to View More

Abstract

A shock absorbing material comprising an Al-Mg-Si series aluminum alloy having high strength and showing excellent energy absorbing property when compressed in the axial direction of extrusion is obtained. The shock absorbing material of the invention has a hollow cross section, mainly comprises a fibrous structure and can be manufactured by press quenching just after extrusion followed by aging. In the press quenching, press quenching under air-cooling advantageous in view of the dimensional accuracy or the cost can be adopted. Further, the shock absorbing material of the invention has excellent cracking resistance to a compressive load in the lateral direction as well as in the axial direction. The shock absorbing material of the invention is suitable as side members or bumper stays in the frame structures of automobiles.

Description

[0001] 1. Field of the Invention[0002] The present invention concerns a shock absorbing material comprising an Al--Mg--Si series aluminum alloy extrusion material and having a function of absorbing impact loads when undergoing compressive impact loads. The shock absorbing material according to the present invention is suitable, for example, to side members, bumper stays or side frames in frame structures of automobiles.[0003] 2. Related Art[0004] In the frame structures for automobiles, it has been considered the use of aluminum alloy hollow extrusion materials in view of reduction of weight as shock absorbing materials such as side members or bumper stays. The shock absorbing materials undergoing axial compressive impact loads are required not to suffer from Eulerian buckling for the entire shape material (buckling in which the entire shape material is bent in an angled form) when undergoing loads in the axial direction of extrusion, to cause shrinking deformation in a bellows form...

Claims

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

Application Information

Patent Timeline
no application Login to View More
Patent Type & Authority Applications(United States)
IPC IPC(8): B21C23/01C22C21/02C22C21/06C22C21/08
CPCB21C23/085B60R19/03C22C21/02C22C21/06C22C21/08Y10T428/12C22F1/043C22F1/047C22F1/05Y10T428/12292C22F1/002
Inventor KAWAI, HITOSHIYOSHIHARA, SHINJIHIRANO, MASAKAZU
Owner KOBE STEEL LTD
Who we serve
  • R&D Engineer
  • R&D Manager
  • IP Professional
Why Eureka
  • Industry Leading Data Capabilities
  • Powerful AI technology
  • Patent DNA Extraction
Social media
Eureka Blog
Learn More
PatSnap group products