Nippon Steel Sumitomo Metal Corporation

Sumitomo Metal Industries, Inc.

Toyoda Iron Works Co., Ltd.

Michitaka Yoshida

Naoaki Shimada

Atsushi Tomizawa

Yoshiaki Nakazawa

Kenji Tamura

Nobusato Kojima

Mitsutoshi Kano

Katsutoshi Takagi

Kazuo Uematsu

Not only a reduction in the load resistant performance of a structural member in a vehicle body having a quenched portion with a tensile strength of 1,470 MPa or greater, but also a reduction in the shock absorbing performance associated with the HAZ softening by welding are suppressed. In a joining structure () for a member in a vehicle body in which a first member () that is made of steel, has a closed hollow cross-section having no outward flange, and is provided with a quenched portion having a tensile strength of 1,470 MPa or greater, a base material portion having a tensile strength of less than 700 MPa, and a transition portion () between the quenched portion () and the base material portion () in a longitudinal direction thereof, and a second member () that is made of steel and overlaps the first member () are welded to each other in an overlapping portion, the overlapping portion exists over the base material portion () from the quenched portion () of the first member () through the transition portion (), and a welding portion () formed by welding exists in the transition portion () or the base material portion () in the first member ().

Joining structure for member in vehicle body

A side structure for an automobile body has an A-pillar having a first portion which has a closed cross section and which is connected to a side sill and extends upwards, and a second portion which has a closed cross section and which is continuous with the first portion and extends along a slope therefrom, and a roof rail side member which has a closed cross section and which is continuous with the A-pillar and is connected to a B-pillar. The side reinforcing member having a closed cross section and a shape which is bent three-dimensionally and which is constituted by a single member in the axial direction and has undergone high frequency quenching is disposed so a to extend at least inside the second portion and inside the roof rail side member to be positioned to the rear of the connection with the B-pillar.

Strength member for an automobile body, front side member, and side structure for an automobile body

An arm material for an upper arm or a lower arm is provided which constitutes a double wishbone suspension or the like of an automobile and which has a flat, hollow, closed cross-sectional shape and enables further decreases in size, decreases in weight, and increases in strength. An arm material for an automobile suspension has a body made from a parts material made by metal. The parts material made by metal has a flat, hollow, closed cross-sectional shape having a pair of opposing long sides and is formed from a single member in its lengthwise direction. The body has at least a first bent portion which is bent in a plane roughly parallel to the pair of long sides.

Arm material and a method for its manufacture

A lightweight hollow member having excellent stiffness and impact properties and which is suitable for automotive parts due to having a high strength such as at least 780 MPa and a complicated shape is provided. A hollow memberhas a hollow steel body. The bodyis constituted by a single member at least in the lengthwise direction. The bodyhas a flat cross section having at least a portion with a maximum outer dimension Land a portion with an outer dimension Lshorter than the maximum outer dimension L. The bodyhas a twisted portion in a portion of its length. The angle of intersection between an imaginary planeincluding the portion having the maximum outer dimension Lin a first portionpresent on one side of the bodyin the lengthwise direction with the twisted portionas a border and an imaginary planeincluding the portion with the maximum outer dimension Lin a second portionpresent on the other side in the lengthwise direction of the bodywith the twisted portionas a border is at least 4 degrees. The twisted portionhas a tensile strength of at least 780 MPa.

Hollow member

A front side member having a single body formed from a tubular body having a closed cross section has a front portion which extends in the fore and aft direction of a vehicle body, a sloping portion which is continuous with the front portion and slopes downwards along a dash panel, and a rear portion continuous with the sloping portion and extending along the bottom surface of a floor panel joined to the dash panel. A portion of the front portion is an unquenched portion which has not undergone quenching treatment and the remainder is a high frequency quenched portion which has undergone high frequency quenching. The sloping portion is a high frequency quenched portion. A portion of the rear portion is an unquenched portion which has not undergone quenching and the remainder other than that portion is a high frequency quenched portion which has undergone high frequency quenching.

A strength member for an automobile body such as a side member or a pillar which has a bent portion which is bent two-dimensionally or three-dimensionally and which has an ultrahigh strength with a tensile strength exceeding 1100 MPa is provided. The strength member for an automobile body has a tubular body which has a closed cross section which does not have an outwardly-extending flange and which has a bent portion which is bent two-dimensionally or three-dimensionally, a portion to be cut or punched, and a portion to be welded. The tubular body has an ultrahigh strength heat-treated portion which has been heat treated to have a tensile strength exceeding 1100 MPa, a high strength heat-treated portion which is the remainder other than the ultrahigh strength heat-treated portion and which has been heat treated to have a tensile strength of at least 600 MPa and at most 1100 MPa, and/or a low strength heat-treated portion which is the portion to be cut or punched or the portion to be welded and which has been heat treated to have a tensile strength of less than 600 MPa.

A crash energy absorption member is provided which has excellent crash energy absorbing properties with the ability of repeated buckling in a stable manner, a high average load at the time of collapse, and the maximum load which is within a range which does not break other members. It is a crash energy absorption member which preferably has a transverse cross-sectional shape of an octagon and which is intended for absorbing impact energy by buckling in the lengthwise direction into a shape of bellows when it receives an impact load. With respect to at least one side forming the transverse cross-sectional shape, when the angle formed by the two sides which adjoin the opposing ends of the one side is &#x3b1;, the relationship between the length L1 of the one side and the distance L2 between the two furthest ends of the two sides interposing the one side satisfies the following equation:0&#x3c;1/2&#x3c;1/{2&#xd7;sin(&#x3b1;/2)+1}.

Crash box

A crash energy absorption member capable of reducing the initial load without provision of a crushing bead and capable of achieving a sufficient amount of shock absorption with stable buckling behavior. The crash energy absorption member is formed from a tubular body which has a length L and a polygonal transverse cross-sectional shape with 2n corners due to having 2n ridge lines (wherein n is a natural number greater than or equal to 3) and 2n surfaces partitioned by these 2n ridge lines, and which absorbs impact energy by buckling when an impact load is applied to one end in the axial direction towards the other end, characterized in that some of the 2n ridge lines only exist in a region which extends from a position spaced by a distance h in the axial direction from the one end to the other end, and if the number of the remaining ridge lines which have a length L is m, the following equations are satisfied:&#xd7;0.30 &#x2003;&#x2003;(1)4&#x2266;&#x2266;2&#xd7;(&#x2212;1). &#x2003;&#x2003;(2)

Crash energy absorption member

A crash energy absorption member formed from a tubular body for absorbing impact energy by buckling when it receives an impact load in the axial direction from one end in the axial direction. It has a transverse cross-sectional shape along at least a portion in the axial direction which is a closed cross section having a plurality of vertices in which there is no flange on the outside of the closed cross section, and in a region of at least one side of a basic cross section formed from the largest outline obtained by connecting a portion of the plurality of vertices by straight lines, a groove which is recessed towards the inside of the outline is provided in a location other than at an end point of the side. Thus, the crash energy absorption member can achieve a prescribed amount of shock absorption by stably buckling in the axial direction without bending and without an increase in weight due to the addition of a partition or due to an increase in plate thickness.

Growing community of inventors

Amagasaki, Japan

Michitaka Yoshida