JP2001130444A - Impact energy absorbing member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an impact energy absorbing member that can appreciably absorb impact energy. SOLUTION: An impact energy absorbing member 1A, 1B has a given cross- sectional form, and absorbs impact energy when deformed under a impact load in the surface direction. The collision energy absorbing member 1A, 1B consists of a steel plate having a structure including austenite in an area rate of 60% or above, or of a steel plate including austenite adapted to generate martensite through a strain-induced transformation and having a strain hardening exponent of 0.26 or above.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a collision energy absorbing member improved so as to efficiently absorb collision energy.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. 9-277953 (publication:
1997) discloses a cylindrical collision energy absorbing member that absorbs collision energy by buckling and deforming under a collision load along the longitudinal direction. In this publication, the collision energy can be efficiently absorbed by the shape of the member.

Japanese Patent Application Laid-Open No. 11-61326 (publication: 1999) discloses that the occupation ratio (area ratio) of retained austenite is 5 to 50%, the average crystal grain size of retained austenite is 5 μm or less, and Curing index is 0.
13 or more, yield ratio 85% or less, tensile strength x total elongation 2
A high-strength steel sheet for automobiles excellent in collision safety and formability, which has a hole expansion ratio of 0000 or more and a hole expansion ratio of 1.2 or more, is disclosed. In this case, as described above, the occupation ratio of retained austenite is 5 to 50%, and the balance is ferrite and martensite. The upper limit of the work hardening index disclosed in this publication is about 0.22. In this publication, the amount of dynamic energy absorption is increased by the material properties of a steel sheet. However, the ratio of a ferrite structure is considerably high, and mainly the ferrite is used.

[0004]

SUMMARY OF THE INVENTION The above-mentioned Japanese Patent Application Laid-open No. Hei 9-2
The technique according to JP 77953 uses the shape of the collision energy absorbing member, and does not disclose an improvement in the material.

The technique disclosed in Japanese Patent Application Laid-Open No. H11-61326 is based on ferrite but contains austenite as described above. Since ferrite has a body-centered cubic crystal structure, it has few slip systems, does not always have sufficient deformability during plastic deformation, and has a low work hardening index of about 0.10 to 0.20. For this reason, when a shocking impact load acts, cracks, tears, and the like are likely to occur during the deformation of the steel sheet. When cracks, tears, etc. occur in this manner, the absorption of collision energy is reduced, so that uneven buckling is likely to occur, and the performance of efficiently absorbing collision energy is reduced.

The technique disclosed in Japanese Patent Application Laid-Open No. H11-61326 is not based on work-induced transformation of retained austenite, even if it occurs, and has a low work hardening index. However, the absorption of collision energy is not always sufficient.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a collision energy absorbing member that can enhance the absorption of collision energy.

[0008]

A collision energy absorbing member according to a first aspect of the present invention has a predetermined cross-sectional shape and is deformed by receiving a collision load along a surface direction to thereby absorb the collision energy. The member is characterized in that austenite is formed using a steel sheet having a structure having an area ratio of 60% or more.

A collision energy absorbing member according to a second aspect of the present invention
A collision energy absorbing member that has a predetermined cross-sectional shape and absorbs collision energy by deforming under a collision load along the surface direction has austenite capable of generating martensite by work-induced transformation, and has a work hardening index. Is configured using a steel plate of 0.26 or more.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The collision energy absorbing member according to the first invention is made of a steel sheet having a structure in which austenite has an area ratio of 60% or more. The entirety of the collision energy absorbing member may be formed of only the above-described steel plate, or a part of the collision energy absorbing member may be formed of the above-described steel plate.

Since the austenite structure has a face-centered cubic crystal structure, the crystal has more slip systems than ferrite having a body-centered cubic crystal structure. For this reason, it is rich in extensibility. Highly extensible even at very low temperatures. For this reason, when the collision energy absorbing member is deformed by receiving a collision load, local cracks, tears, and the like are less likely to occur. Therefore, the overall deformability of the collision energy absorbing member can be easily made uniform, and the collision energy absorbing performance can be secured well.

[0012] The collision energy absorbing member according to the first aspect of the present invention comprises:
As described above, it is configured using a steel plate having a structure in which the area ratio of austenite is considerably high. In this steel sheet, the ratio of the austenitic structure is selected in consideration of factors such as the type and use of the collision energy absorbing member, the required collision absorption form, and cost.
%, 98% or more, 96% or more, or 94% or more, 92% or more, or 90% or more. 85% or more, 75% or more, 70% or more, 6
It can be any of 5% or more. Therefore, N
It is preferable to include an austenite stabilizing element such as i, Mn, C, or N.

In consideration of the improvement of the collision energy absorbing performance, the collision energy absorbing member according to the first invention is preferably formed of a steel plate substantially having an austenitic structure. According to the collision energy absorbing member according to the first invention, austenite is a stable austenite that is less likely to undergo transformation such as martensitic transformation than unstable austenite or metastable austenite that readily undergoes transformation such as martensitic transformation. preferable.

The steel of the collision energy absorbing member according to the first invention has a composition not so close to the mixed structure (A + M) of austenite and martensite in the phase diagram shown in FIG. Can be adopted. In other words, the steel of the collision energy absorbing member according to the first invention has an N, which is not excessively close to the following equation.
A composition having i-equivalent and Cr-equivalent, that is, a structure of stable austenite that does not cause or hardly causes transformation such as martensitic transformation can be employed.

Incidentally, even in the steel sheet according to the collision energy absorbing member according to the first invention, if the steel sheet has a composition close to the mixed structure (A + M) of austenite and martensite, the stability of austenite is not improved. Because it will be lower
When a shocking impact load is applied, austenite may be transformed into martensite by work-induced transformation. In this case, in addition to securing the collision energy absorption due to the large number of slip systems, it can be expected to secure the collision energy absorption due to the work-induced transformation.

A collision energy absorbing member according to a second aspect of the present invention comprises:
Austenitic steel capable of forming martensite by work-induced transformation and having a work hardening index of 0.26 or more is used. If the work hardening index is equal to or more than a specific value, austenite is easily transformed into martensite by work induced transformation under the influence of an impact impact load, and the metal structure becomes hard. Since the hardened portion is less likely to be deformed further, the austenite in the not-yet-deformed portion is liable to be transformed into martensite by work-induced transformation under the influence of a shocking impact load. For this reason, the deformation propagation characteristics at the time of a collision are improved, and the performance of absorbing the collision energy is ensured.

According to the collision energy absorbing member of the second invention, the work hardening index is 0.27, although it differs depending on the place where the collision energy absorbing member is used, the size of the collision energy absorbing member, the collision type and the cost. Above, 0.
28 or more, 0.29 or more, 0.30 or more, 0.31 or more, 0.32 or more, 0.33 or more, 0.34 or more, 0.
It can be any one of 35 or more, 0.36 or more, 0.37 or more, 0.38 or more. Considering the degree of precipitation of work-induced martensitic transformation even for austenite, the upper limit of the work hardening index is 0.70, 0.
It is considered that either 71 or 0.72 is preferable.

Therefore, according to the collision energy absorbing member of the second invention, the work hardening index is, for example, 0.26 to 042,
0.30-0.38, 0.32-0.38, 0.30
0.40. However, it is not limited to these.

In the case of a steel sheet mainly composed of ferrite, the work hardening index is generally from 0.15 to 0.20, and is as high as 0.24.

The work hardening index is generally determined by conducting a static tensile test and measuring the load and elongation. It is considered that the value of the work hardening index basically depends on the material, and does not basically depend on the shape of the test piece.

In the collision energy absorbing member according to the second aspect of the present invention, the work hardening index is high as described above because austenite is transformed into martensite by work-induced transformation, and hardens with the formation of martensite. Because.

In the collision energy absorbing member according to the second aspect of the present invention, a member substantially consisting of an austenite structure having a property of transforming into martensite by work induced transformation can be employed. Alternatively, those having an austenitic structure and a ferrite structure (area ratio of 10% or less, substantially austenite in the remainder) can be employed. In the former case, although it is substantially composed of an austenite structure, the composition diagram in the phase diagram shown in FIG. 4 shows a mixed structure of austenite and martensite (A
+ M). In the latter case,
Depending on the application and cost, the ferrite structure in the steel sheet is 5% or less, 4% or less, 3% or less, 2% or less in area ratio,
A steel sheet having 1% or less and a balance substantially having an austenite structure can be employed.

The collision energy absorbing member according to the first invention and the second invention absorbs collision energy by having a predetermined cross-sectional shape and deforming under a collision load along a surface direction. Such a collision energy absorbing member has a tubular shape having a square cross section (including a square and a rectangle), a cylindrical shape having a circular shape (including a circle, an ellipse, and an ellipse), or an L-shaped cross section. An angle shape having a shape or a channel shape having a U-shaped cross section can be adopted.

Therefore, the cross section of the collision energy absorbing member is
Open section such as L-shaped, pseudo-L-shaped, Y-shaped, pseudo-Y-shaped, I-shaped, pseudo-I-shaped, U-shaped, pseudo-U-shaped, or a circle, square, polygon Etc. may be used. In addition, the above-mentioned L character, pseudo L character, Y character, pseudo Y character, I character, pseudo I character, U character, pseudo U character, S character, pseudo S character, etc. The cross-sectional shape may include at least one typeface.

In order to make the collision energy absorbing member easily receive a collision load in the plane direction of the collision energy absorbing member, if the collision energy absorbing member has a hollow portion, the charged material such as powder, foam, core, etc. Inserted inside the collision energy absorbing member,
It is also preferable to increase the rigidity of the collision energy absorbing member in the longitudinal direction. Thereby, it is easy to suppress the bending of the collision energy absorbing member.

The collision energy absorbing member may be of a short form having a short length or a long form having a long length.
However, the collision energy absorbing member is not limited to these forms.

In short, the collision energy absorbing members according to the first invention and the second invention only need to receive a collision load along a surface direction. If the collision energy absorbing member according to the first invention or the second invention is applied to a vehicle body component member of a vehicle, it is possible to improve the absorption of collision energy at the time of a vehicle collision.

[0028]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) Embodiment 1 FIGS. 1 to 3
This will be described with reference to FIG. The collision energy absorbing member 1A according to the present embodiment is equivalent to the first invention, and has a predetermined cross-sectional shape and receives a shocking collision load along a surface direction (direction of an arrow W1) to buckle. By doing so, the collision energy is absorbed. Specifically, the collision energy absorbing member 1A has a first member 10A having a substantially U-shaped cross section and a first flange portion 11A extending outward and a substantially U-shaped cross section. And a second member 20A having a second flange portion 21A extending outward and having a U-shape, and the first flange portion 11A and the second flange portion 21A are integrally welded in a superposed state. By joining, it has a cylindrical shape. This collision energy absorbing member 1A simulates a rocker panel which is a component of an automobile body used in a vehicle.

The steel sheets constituting the first member 10A and the second member 20A are of the same material and have a substantially austenitic structure, that is, substantially 10% of austenite in area ratio.
It is formed of 0% steel (polycrystalline structure).

FIG. 3 shows a state diagram of the structure when the horizontal axis is Cr equivalent and the vertical axis is Ni equivalent. In FIG. 3, A means austenite, M means martensite, and F means ferrite. Ni equivalent and Cr
The equivalent is obtained by the following equation. The content means mass% (= weight%).

Ni equivalent =% Ni (Ni content) + 30 ×
% C (carbon content) + 0.5 ×% Mn (manganese content) Cr equivalent =% Cr (Cr content) +% Mo (Mo content) + 1.5 ×% Si (silicon content) +0.5 ×%
Nb (niobium content) The composition of this steel sheet is set within a region α indicated by hatching shown in FIG. 3 when defined by Ni equivalent (%) and Cr equivalent (%). The region α indicates a structure substantially composed of austenite.

In FIG. 3, an area α is an area divided by equations, equations, and equations. The expression is expressed as a linear function having Ni equivalent and Cr equivalent as factors, as shown in Expression 1 (Equation 1). The equation is expressed as a linear function having Ni equivalent and Cr equivalent as factors, as shown in Equation 2 (Equation 2). As shown in FIG. 3, the equation means that the Ni equivalent is 30%. Here, similarly to a general linear function, the slope of a straight line represented by the equation and the linear function of the equation is (increase in the vertical axis / increase in the horizontal axis),
That is, it is defined as (increase in Ni equivalent / increase in Cr equivalent). The intercept of the straight line represented by the equation and the linear function of the equation is defined by the Ni equivalent when the Cr equivalent is 0%.

The above-mentioned region α is a region below the characteristic line shown by the equation, an area above the characteristic line shown by the equation, and above the characteristic line shown by the equation. Area. This is shown as Equation 6 (Equation 6).

[0035]

(Equation 1)

[0036]

(Equation 2)

[0037]

(Equation 3)

[0038]

(Equation 4)

[0039]

(Equation 5)

[0040]

(Equation 6)

[0041]

(Equation 7)

The composition of the steel sheet according to this embodiment is as follows.
Within the region α, those having the compositions indicated by α1 to α6 can be adopted.

FIG. 2 (b) shows that the collision energy absorbing member 1A according to the present embodiment is deformed by applying a collision load along a surface direction of a steel plate constituting the collision energy absorbing member 1A. As described above, a large number of bent portions 10c are formed in the longitudinal direction, that is, along the axial direction of the collision energy absorbing member 1A, and almost the entire body is easily buckled and deformed in a bellows shape. The reason is that the collision energy absorbing member 1A
Is presumed to be composed of a steel sheet having a substantially 100% austenitic structure. That is, as described above, austenite has a face-centered cubic crystal structure,
Unlike the ferrite-based steel, when the impact energy absorbing member 1A is deformed by receiving an impact impact load, local cracks, tears, and the like are less likely to occur since the slip system is rich in extensibility. This is presumed to be because the overall deformability of the collision energy absorbing member 1A is made uniform and the collision energy absorption performance is secured.

Further, according to the collision energy absorbing member 1A according to the present embodiment, the energy absorption performance at the time of collision is improved. Can be made thinner. This is advantageous for weight reduction.

(Embodiment 2) Embodiment 2 will be described.
The collision energy absorbing member 1B according to the second embodiment corresponds to the second invention, and has the same appearance as the above-described collision energy absorbing member 1A shown in FIG. 1, and will be described with reference to FIG. The impact energy absorbing member 1B has a first member 10B having a substantially U-shaped cross section and a first flange portion 11B extending outward, and a substantially U-shaped cross section. By using a second member 20B having a second flange portion 21B extending outward, the first flange portion 11B and the second flange portion 21B are integrally welded to each other in a state where they are overlapped with each other. It has a cylindrical shape.

This collision energy absorbing member 1B is a model of a rocker panel which is a component of an automobile body used for a vehicle.

The first member 10B and the second member
Are made of the same material. When the composition of the steel sheet according to Example 2 is defined by the Ni equivalent (%) and the Cr equivalent (%), the composition is set in a region β indicated by hatching shown in FIG. In FIG. 4, the region β
Is an area divided by the formula, the formula and the formula.
The equation is expressed by Ni equivalent and Cr as shown in Equation 3 (Equation 3).
Expressed as a linear function with the equivalent as a factor. ceremony,
As shown in Equation 4 (Equation 4), it is expressed as a linear function having Ni equivalent and Cr equivalent as factors. The formula is:
As shown in (Equation 5), it is expressed as a function having Ni equivalent and Cr equivalent as factors.

In other words, as shown in FIG.
Is a region above the characteristic line shown by the formula, is a region below the characteristic line shown by the formula, and is a region above the characteristic line shown by the formula. . This is shown as Equation 7 (Equation 7).

The composition of the steel sheet according to the present embodiment is as follows.
Within the region β, those having compositions represented by β1 to β3 can be adopted.

In other words, the steel sheet according to the second embodiment is
A steel plate having a formula and a composition close to the formula and having a substantially austenitic structure (polycrystalline), that is, 100% austenite in area ratio, or a mixed structure of austenite and ferrite (polycrystalline, 90% austenite in area ratio) , Ferrite (10%). The work hardening index is about 0.5 to 0.7 in the former case, about 0.3 to 0.5 in the latter case,
Both are expensive.

The collision energy absorbing member 1B according to this embodiment
On the other hand, when a collision load is applied along the surface direction of the steel plate forming the collision energy absorbing member 1B to buckle and deform, as in the case of the first embodiment, as shown in FIG. In the direction, that is, along the axial direction of the collision energy absorbing member 1B, a large number of bent portions 10c are formed, and the entire collision energy absorbing member 1 is easily buckled in a bellows shape. The reason is presumed as follows. If the work hardening index of the steel sheet is equal to or more than a specific value, austenite is easily transformed into martensite by work-induced transformation under the influence of a shocking impact load, thereby hardening the metal structure. Since the hardened portion is less likely to be deformed further, the austenite in the not-yet-deformed portion is liable to be transformed into martensite by work-induced transformation under the influence of a shocking impact load. For this reason, the steel sheet is normally plastically deformed to the final area or near the final area of the collision energy absorbing member 1B while suppressing the occurrence of cracks, tears, and the like in the steel sheet.
Therefore, it is presumed that the deformation propagation characteristics at the time of the collision are improved, and the performance of absorbing the collision energy is secured.

Further, according to the collision energy absorbing member 1B according to the present embodiment, if the absorption energy at the time of the collision is substantially the same as that of the conventional product, the thickness of the steel sheet can be reduced, which is advantageous for weight reduction. .

(Test Example 1) A test piece a using a steel plate constituting the collision energy absorbing member 1A according to Example 1 was prepared. Further, a test piece b using a steel plate constituting the collision energy absorbing member 1B according to Example 2 was prepared. The composition of the test piece a corresponds to “a” in the region a according to FIG. The composition of the test piece b is within the range β in FIG.
b ".

Further, a test piece c using the steel sheet of the comparative example and a test piece d using the steel sheet of another comparative example were prepared. Test piece c
Equivalent to TRIP steel (Transformation-induced plasticity). Test piece d corresponds to JIS-SPC590 and is a ferrite single phase.

Table 1 shows the compositions of the steel sheets according to the test pieces a to d.

[0056]

[Table 1]

A static tensile test was performed on each of the test pieces a to d to determine the load-elongation characteristics, and the tensile strength, yield stress, elongation at break, and work hardening index of each test piece were measured. The tensile test was performed using a JIS-5 test piece (plate-shaped test piece) according to JIS-Z2241. Table 2 shows the test results.

[0058]

[Table 2]

The work hardening index n was determined based on the equation (8). In Equation 8 (Equation 8), PA indicates a load [MPa] at an elongation of 5% in the load-elongation characteristics. PB
Is the load at 15% elongation [MP
a]. εA shows a corresponding true strain when the elongation is 5%. εB shows a corresponding true strain when the elongation is 15%. The work hardening index was 0.30 for test piece a and 0.34 for test piece b, both high. The value was 0.23 in the test piece c according to the comparative example, and was as low as 0.19 in the test piece b according to the comparative example.

[0060]

(Equation 8)

(Test Example 2) Using a steel plate (thickness: 1.2 mm) of the same material as the test pieces a to d, cylindrical impact energy absorbing members a1 to d1 (length: 300 mm) shown in FIG. Each was produced. The collision energy absorbing member a1 was set on the load cell such that the longitudinal direction of the collision energy absorbing member a1 was vertical. Then, a weight (weight: 150 kgw) is applied from the height of 12 m to the collision energy absorbing member a.
1 was free-falling toward the upper end portion, thereby crushing the weight against the collision energy absorbing member a1 and crushing it. At the time of crushing, the load cell load was measured every unit time (0.05 msec) using a load cell up to a displacement of 100 mm.

Then, the absorbed energy was determined from the cumulative load value with respect to the displacement. Other collision energy absorbing members b1 to d
The absorption energy of No. 1 was similarly measured. FIG. 5 shows the measurement results. As shown in FIG. 5, as the absorbed energy, the collision energy absorbing member a1 corresponding to the first embodiment is used.
Was about 7800 J, and the collision energy absorbing member b1 corresponding to Example 2 was about 6900 J, which was high.
Impact energy absorbing member c1 corresponding to comparative example (TRIP steel)
Is about 5800 J, which is a comparative example (JIS-SPC59).
0) is equivalent to 4900J.
It was about low. According to the test results shown in FIG.
It can be seen that Examples 1 and 2 have good energy absorption at the time of a collision, and are advantageous in alleviating the collision.

The collision energy absorbing member a1 according to the embodiment,
b1 is, as schematically shown in FIGS. 2B and 2C,
The buckling deformation was not greatly biased, and the whole buckled and deformed in a bellows shape. On the other hand, in both of the collision energy absorbing members c1 and d1 according to the comparative example, as shown schematically in FIG.

FIG. 6 shows the change in absorbed energy in the above-mentioned crush test when the thickness is changed. B as test material
1 was used. As shown in the characteristic line of FIG. 6 using JIS-SPC590 as a comparative example, in order to set the collision absorption energy to U1, the test piece according to the comparative example has a plate thickness of 1.
Although 6 mm was required, in the case of the test piece using the invention steel, the same degree of impact absorption was obtained at a plate thickness of about 1.46 mm. From this, it can be seen that if the absorbed energy at the time of collision is approximately the same as that of the conventional product, the steel plate can be made thinner, which is advantageous for weight reduction.

FIGS. 7A, 7B, 7C, and 7D show displacement-load characteristic lines in Test Example 2. FIG. The greater the number of peaks and valleys in the displacement-load characteristic line, the more the entire collision energy absorbing member buckles in a bellows shape without bias, meaning that it has the property of efficiently absorbing collision energy. FIG.
(A) shows the test result of the collision energy absorbing member a1.
FIG. 7B shows a test result of the collision energy absorbing member b1. FIG. 7C shows a test result of the collision energy absorbing member c1. FIG. 7D shows a test result of the collision energy absorbing member d1.

As shown by the characteristic lines in FIG. 7A and the characteristic line in FIG. 7B, according to the collision energy absorbing members a1 and b1, the number of peaks and valleys in the characteristic lines is large. Was. As shown by the characteristic lines in FIG. 7C and the characteristic line in FIG. 7D, according to the collision energy absorbing members c1 and d1, the collision energy absorbing members a1 and b
The number of peaks and valleys on the characteristic line was smaller than that of 1. 7, the collision energy absorbing members a1,
It can be seen that b1 has good collision energy absorption performance.

(Example) FIG. 8 shows an example applied to a body component of a vehicle. As shown in FIG. 8, the front side member 102, the rear floor side member 104, the front pillar 106, the center pillar 108, the floor underline force 110, the rocker inner 112, the front floor cross member 116, the center floor cross member 118, etc. It is provided as a body component, and these can function as a collision energy absorbing member in a vehicle.

The front side member 102, the rear floor side member 104, and the front pillar 106 extend in the front-back direction of the vehicle body, and are effective against a collision load acting from the front-back direction of the vehicle body. The front floor cross member 116 and the center floor cross member 118 extend along the vehicle width direction of the vehicle body, and are effective against a collision load acting from the vehicle width direction of the vehicle body. Front pillar 106,
The center pillar 108 is along the height direction of the vehicle body,
Effective for loads from the height direction.

As shown in FIG. 9, the front side member 1
Numeral 02 has a cylindrical shape and is arranged along the front-rear direction of the vehicle body.

As shown in FIGS. 10 and 11, the front pillars 106 are arranged so as to be inclined along the height direction of the vehicle body and the longitudinal direction of the vehicle body. As shown in FIG. 11, the front pillar 106 is formed in a tubular shape by assembling a plurality of steel plates 106a to 106c. Plural steel plates 106a
At least one of the steel plates 106 to 106c is made of the steel plate according to the first or second embodiment.

As shown in FIGS. 12 and 13, the center pillar 108 extends along the height of the vehicle body. As shown in FIG. 13, the center pillar 108 includes a plurality of steel plates 108 a to 108 a.
108c is assembled into a cylindrical shape. At least one of the plurality of steel plates 108a to 108c is configured by the steel plate according to the first or second embodiment.

In the above application example, the present invention is applied to a vehicle body component. However, the present invention is not limited to this. For example, a body component used for a transportation device such as a railway vehicle, a ship, an aircraft, or the like may be used. It can also be applied to shock absorbers and the like used for roads, guardrails, dividers and the like.

FIG. 14 shows an embodiment in which a load 50 is loaded in the hollow interior of the collision energy absorbing members 1A and 1B according to another embodiment. Collision energy absorbing member 1A,
Even when the length of 1B is long, the collision energy absorbing members 1A and 1B are hardly bent by the load 50,
An effect that the whole of the collision energy absorbing members 1A and 1B can be more easily buckled and deformed can be expected.

(Supplementary Note) The following technical idea can be understood from the above description.

(Supplementary item 1) The buckling deformation of a predetermined cross-sectional shape by receiving a collision load along the surface direction,
In the collision energy absorbing member that absorbs collision energy, when the Ni equivalent is plotted on the vertical axis and the Cr equivalent is plotted on the horizontal axis, the Ni equivalent and the Cr equivalent are calculated by the above-described formulas.
A collision energy absorbing member comprising a steel plate within a region of a composition surrounded by the formula.

(Supplementary item 2) By buckling and deforming under a collision load along a surface direction having a predetermined cross-sectional shape,
In the collision energy absorbing member that absorbs collision energy, when the Ni equivalent is plotted on the vertical axis and the Cr equivalent is plotted on the horizontal axis, the Ni equivalent and the Cr equivalent are calculated by the above-described formulas.
A collision energy absorbing member comprising a steel plate within a region of a composition surrounded by the formula.

(Additional Item 3) A vehicle body provided with a collision energy absorbing member, wherein the collision energy absorbing member is defined by at least one of Claims 1, 2, 2, and 3. A vehicle body characterized in that:

(Appendix 4) A vehicle body provided with a collision energy absorbing member, wherein the collision energy absorbing member is defined by at least one of claim 1, claim 2, claim 1 and claim 2. And a vehicle body arranged along at least one of the front-rear direction, the vehicle width direction, and the height direction of the vehicle body.

(Additional Item 5) A collision energy absorbing member that absorbs collision energy by being deformed under a collision load, wherein the austenite is made of a steel plate having a structure having an area ratio of 60% or more. A collision energy absorbing member characterized by the following.

(Additional Item 6) A collision energy absorbing member that absorbs collision energy by deforming under a collision load has austenite capable of forming martensite by work-induced transformation and has a work hardening index of 0.2.
A collision energy absorbing member comprising at least six steel plates.

[0081]

The collision energy absorbing member according to the first invention,
According to the collision energy absorbing member according to the second aspect of the present invention, when a collision load is applied in a plane direction, the absorption of the collision energy can be improved.

Therefore, if the absorbed energy at the time of collision is almost the same as that of the conventional product, it is advantageous for weight reduction.

The impact energy absorbing member according to the first invention and the impact energy absorbing member according to the second invention are austenitic, so that press formability can be ensured and even if they have complicated shapes. Good press forming is possible.

[Brief description of the drawings]

FIG. 1 is a perspective view of a collision energy absorbing member.

FIG. 2 is a perspective view showing a buckling configuration of a collision energy absorbing member.

FIG. 3 is a state diagram of the steel sheet according to the first embodiment.

FIG. 4 is a state diagram of a steel sheet according to a second embodiment.

FIG. 5 is a graph showing collision absorption energy.

FIG. 6 is a graph showing a relationship between a plate thickness and a collision absorption energy.

FIG. 7 is a graph showing a load-displacement when a crush test is performed.

FIG. 8 is a perspective view showing body components of the vehicle.

FIG. 9 is a perspective view showing a front side member.

FIG. 10 is a perspective view showing a front pillar.

FIG. 11 is a perspective view of a main part showing an internal structure of a front pillar.

FIG. 12 is a side view showing a center pillar.

FIG. 13 is a perspective view of a main part showing an internal structure of a center pillar.

FIG. 14 is a perspective view of a collision energy absorbing member having a load loaded therein according to another embodiment.

[Explanation of symbols]

In the figure, 1A and 1B are collision energy absorbing members, 10A and 1B.
0B is a first member, and 20A and 20B are second members.

Claims (2)

[Claims] A collision energy absorbing member having a predetermined cross-sectional shape and deforming under a collision load along a surface direction to absorb collision energy, wherein austenite has a structure having an area ratio of 60% or more. A collision energy absorbing member comprising a steel plate. 2. A collision energy absorbing member having a predetermined cross-sectional shape and receiving a collision load along a surface direction and deforming to absorb collision energy, wherein austenite capable of generating martensite by processing-induced transformation is provided. A collision energy absorbing member comprising a steel plate having a work hardening index of 0.26 or more.