Jfe Steel Corporation

Kobe Steel, Ltd.

Rinsei Ikeda

Hiroshi Matsuda

Koichi Taniguchi

Chikaumi Sawanishi

Muneo Matsushita

Yasuaki Okita

Katsutoshi Takashima

Kenji Oi

Takashi Kobayashi

Minoru Tanaka

Koichi Nakagawa

Yoshiyasu Kawasaki

Toyohisa Shinmiya

Yuji Hashimoto

Reiichi Suzuki

Koji Suzuki

Satoru Ando

Seiji Nakajima

Yasushi Kitani

Osamu Sonobe

Akio Sato

Reiko Endo

Minoru Miyata

Sachiko Suzuki

Rinta Sato

Akihide Yoshitake

Daiki Yamagishi

A welding process used in a method of manufacturing a steel sheet assembly includes spot welding steel sheets performed for a heat time of 0.08 seconds or more using a convex electrode with a tip radius of curvature of 20 mm or more or a flat electrode such that the weld force F (kN) for initial 0.03 seconds of the heat time satisfies formula: F<0.00125×(1+0.75×t)+3 where TS (MPa) denotes an average strength of the steel sheets and represents a weighted mean value of a thickness of each of the steel sheets, and t(mm) denotes a total thickness of the steel sheets (the sum of the thicknesses of the steel sheets).

Steel sheet assembly, method of manufacturing steel sheet assembly, and spot welding process

Disclosed are rotating tools for double-sided friction stir welding that are applied to double-sided friction stir welding, which is a technique for welding two metal plates by rotating a pair of rotating tools, which oppose each other, in opposite directions, a double-sided friction stir welding apparatus that uses the rotating tools, and a double-sided friction stir welding method. A pair of rotating tools for double-sided friction stir welding that are used in double-sided friction stir welding, which is a technique for welding metal plates by using a pair of rotating tools that are each disposed on one of first and second surfaces of an unwelded portion of the metal plates such that the rotating tools rotate in opposite directions, include end portions each of which is formed in a circular and planar shape. The end portions are each made of a material harder than the metal plates.

Rotating tool for double-sided friction stir welding, double-sided friction stir welding apparatus, and double-sided friction stir welding method

A resistance spot welding method comprises: performing test welding; and performing actual welding after the test welding, wherein in main current passage in the actual welding, adaptive control welding is performed, and in subsequent current passage in the actual welding, current passage is performed by constant current control with a current determined based on an electrical property between electrodes in each of main current passage in the test welding and the main current passage in the actual welding.

Resistance spot welding method and weld member production method

A gas-shielded arc welding method includes welding a steel plate having a tensile strength of 780 MPa or more while feeding a consumable electrode via a welding torch and flowing a shielding gas. The consumable electrode includes, in mass %, C: 0 to 0.20%, Si: 0 to 0.50%, Mn: 0 to 0.50%, Cr: 1.00% to 9.00%, S: 0.0020% to 0.0600%, and Ni: 0 to 0.50%. The shielding gas includes, in vol. %, at least one of COand O: 1% to 15% in total, with the remainder being Ar and unavoidable impurities. Welding is performed under the condition satisfying the relationship of 1≤{−0.05×[CO+O]}+[Cr]≤8.3, and [Cr] represents the content of Cr in the consumable electrode, and [CO+O] represents a total content of at least one of COand Oin the shielding gas.

Gas-shielded arc welding method and method for manufacturing welded structure

Provided is a double-side friction stir welding method of metal sheets or metal plates to each other, and a double-side friction stir device for performing the double-side friction stir welding. According to the present invention, a pair of rotating tools facing each other is respectively arranged on a top-surface side and a bottom-surface side of a butted portion or an overlapping portion, which comprises a joint portion of two metal sheets or two metal plates, the pair of rotating tools is moved in a welding direction while being rotated at the butted portion or the overlapping portion, and while the metal sheets or the metal plates are softened by frictional heat generated between the rotating tools and the metal sheets or the metal plates, softened parts are stirred by the rotating tools to produce a plastic flow to join the metal sheets or the metal plates to each other.

Double-side friction stir welding method and double-side friction stir welding device for metal sheets or metal plates

A spot welded member includes a spot weld formed by holding a sheet stack of multiple steel sheets between a pair of electrodes and spot-welding the sheet stack, in which at least one of the multiple steel sheets is a high-strength zinc-based coated steel sheet having a tensile strength of 780 MPa or more, the high-strength zinc-based coated steel sheet having a coating with an Al content of 0.5% or more by mass, and in which the heat shock region of the spot weld outwardly extending from an edge of a corona bond area includes a coated layer including an FeAl alloy layer having an average thickness of 0.3 μm or more and a zinc-based coated layer having an average thickness of 2.0 μm or more on the FeAl alloy layer at the interface between the base steel sheet of the high-strength zinc-based coated steel sheet and the coating.

Spot welded member

The present invention provides a resistance spot welding method. A resistance spot welding method according to the present invention in which a sheet combination of two or more overlapping steel sheets is sandwiched between a pair of electrodes and joined together by applying current while applying pressure, the method including a main current application step in which current application is performed with a current I(kA), and subsequently, a post-tempering heat treatment step in which after cooling is performed for a cooling time t(ms) shown in formula (1) below, current application is performed with a current I(kA) shown in formula (2) below for a current application time t(ms) shown in formula (3) below: 800≤t. . . formula (1), 0.5×I≤I≤I. . . formula (2), and 500≤t. . . formula (3).

Resistance spot welding method and method for producing resistance spot welded joint

A resistance spot welding method includes: performing test welding; and performing actual welding after the test welding, wherein in subsequent current passage in the test welding, current passage is performed by constant current control under a condition: 0.5 δ Vtp/Vtm δ 2.0 when tc<800 ms; 0.5−0.3·(tc−800)/800 δ Vtp/Vtm δ 2.0−0.5·(tc−800)/800 when 800 ms δ tc<1600 ms; and 0.2 δ Vtp/Vtm δ 1.5 when tc ε 1600 ms, and wherein in main current passage in the actual welding, adaptive control welding is performed, and in subsequent current passage in the actual welding, current passage is performed by constant current control under a condition: 0.8·Itp δ Imp δ 1.2·Itp.

A resistance spot welding method comprises: performing test welding; and performing actual welding after the test welding, wherein the test welding is performed under each of two or more welding conditions. In the test welding, for each of the welding conditions, an electrode force parameter from when electrode force application to parts to be welded starts to when a set electrode force is reached before start of current passage and a time variation curve of an instantaneous amount of heat generated and a cumulative amount of heat generated are stored. In the actual welding: electrode force application to the parts to be welded is performed under each of the same conditions as in the test welding before start of current passage, and a corresponding electrode force parameter and the parameter stored in the test welding are compared for each of the welding conditions to set a target of a time variation curve of an instantaneous amount of heat generated and a cumulative amount of heat generated in the actual welding; and adaptive control welding is performed to control a current passage amount according to the target.

A resistance spot welding method comprises: performing test welding; and performing actual welding after the test welding, wherein in the test welding, 0.2≤Vtp/Vtm≤1.5 is satisfied where Vtm is an average value of a voltage between the electrodes in main current passage in the test welding and Vtp is an average value of a voltage between the electrodes in subsequent current passage in the test welding, and in each of main current passage and subsequent current passage in the actual welding, a time variation curve of an instantaneous amount of heat generated per unit volume and a cumulative amount of heat generated per unit volume that are stored in a corresponding one of the main current passage and the subsequent current passage in the test welding are set as a target, and adaptive control welding is performed to control a current passage amount according to the target.

A resistance spot welding method comprises: performing test welding; and performing actual welding after the test welding. The test welding is performed under each of two or more welding conditions. In the actual welding, preliminary current passage is performed by constant current control in the same current pattern as in the preliminary current passage of the test welding, an electrical property between the electrodes in the preliminary current passage in the actual welding and an electrical property between the electrodes stored in the preliminary current passage in the test welding are compared for each welding condition to set a target in main current passage in the actual welding, and thereafter adaptive control welding is performed to control a current passage amount as the main current passage.

Proposed is a resistance spot welding method to join parts to be welded which are a plurality of overlapping metal sheets, including: dividing a current pattern into two or more steps for welding; before actual welding, performing test welding; and subsequently, as actual welding, performing adaptive control welding, in which the two or more steps for welding include a step of securing a current path between the sheets directly below the electrodes and a subsequent step of forming a nugget having a predetermined diameter, and a welding interval time is provided between these steps. This method thus yields a good nugget without causing splashing even under special welding conditions.

Resistance spot welding method

Main current passage and subsequent current passage are performed, with a cooling time of 0.01 s or more being provided between the main current passage and the subsequent current passage. Ip/I which is a ratio of a current value of the subsequent current passage to a current value of the main current passage is controlled to satisfy a predetermined relationship depending on a constant A defined by Mn content and P content of a steel sheet as a part to be welded, in relation to a welding time Tp of the subsequent current passage, a cooling time T, and the constant A.

There is provided a friction stir welding method in which, when double-sided friction stir welding is performed, enough plastic flow to obtain a welded state uniform in the thickness direction of metal sheets can be obtained, in which an increase in welding speed is achieved while the occurrence of defects during welding is prevented, and in which sufficient strength and improvement in welding workability can be achieved. There is also provided a friction stir welding device suitable for the friction stir welding.

Double-sided friction stir welding method for metal sheets and double-sided friction stir welding device

Provided is a resistance spot welding method. The resistance spot welding method for joining a sheet set including a plurality of lapped steel sheets includes: holding the sheet set between a pair of electrodes; and energizing the sheet set under application of electrode force to thereby join the steel sheets together. At least one of the plurality of lapped steel sheets is a surface-treated steel sheet including a metal coating layer on a surface thereof. The energizing includes: a primary energizing step of performing energization to form a nugget portion; a non-energizing step in which, after the primary energizing step, the energization is suspended for an energization suspension time Tc (cycles); and a secondary energizing step of, after the non-energizing step, performing energization for reheating while the nugget portion is prevented from growing. During the energizing, the relations of a particular formula are satisfied.

Growing community of inventors

Tokyo, Japan

Rinsei Ikeda