# US 10,766,099 B2 · Friction stir welding apparatus for structural steel > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,766,099 B2 - Document ID: US10766099B2 - Status: Granted - Kind: B2 - Application number: 15/556,792 - Filed: 2016-03-17 - Published: 2018-02-15 - Granted: 2020-09-08 - Earliest claimed: 2015-03-19 - Assignees: Jfe Steel Corporation - Applicants: Jfe Steel Corporation - Inventors: Muneo Matsushita; Koichi Taniguchi; Rinsei Ikeda - Web page: https://patentgrep.com/patent/US10766099B2 ## CPC - B23K 20/1235: {with temperature control during joining} - B23K 20/125: {Rotary tool drive mechanism} - B23K 20/12: the heat being generated by friction; Friction welding - B23K 20/1225: {Particular aspects of welding with a non-consumable tool} - B23K 20/1245: {characterised by the apparatus} - B23K 20/227: with ferrous layer - B23K 20/24: Preliminary treatment - B23K 20/26: Auxiliary equipment - B23K 37/003: Cooling means for welding or cutting - B23K 2101/18: Sheet panels - B23K 2103/04: Steel {or steel} alloys - B23K: SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM ## Abstract A friction stir welding apparatus that includes a rotary tool and a heating device. The heating device is placed in front of the rotary tool to heat steel sheets that are used as a workpiece. The rotary tool is moved in the welding direction so that steel sheet is softened by frictional heat. Additionally, the surface temperature, the area, and the position of the heated region during the heating process are strictly controlled. The heating of the steel sheets by the welding apparatus provides sufficient strength and good welding workability by advantageously eliminating plastic flow defects generated due to insufficient heating of workpieces. ## Claims ### Claim 1 A friction stir welding apparatus for structural steel, the welding apparatus comprising: a rotary tool that includes a shoulder and a pin disposed on the shoulder, the pin sharing a rotation axis with the shoulder, at least the shoulder and the pin being made of a material that is harder than steel sheets that are used as workpieces, a front heating device that is provided in front of the rotary tool and positioned higher than a top surface of the rotary tool, and a rear heating device provided behind the rotary tool and positioned lower than the front heating device, wherein: the front heating device is adapted to: form a heated region on the steel sheets such that: (a) a center of the heated region is located on the advancing side; and (b) a distance from the center of the heated region to the welding centerline is from 0.5 times to 1 time a maximum radius of the pin of the rotary tool, the heated region having a temperature TS (° C.) that satisfies TS≥0.8×TA1 (such that TA1 is described in Formula (1) below) TA1(° C.)=723−10.7[% Mn]−16.9[% Ni]+29.1[% Si]+16.9[% Cr]+290 [% As]+6.38[% W] Formula (1), where [% M] represents an amount (mass %) of element M in the steel sheets used as a workpiece, the rotary tool is adapted to penetrate into a non-welded part of the steel sheets and to move in a welding direction while the rotary tool rotates so that a portion of the steel sheets which has been preheated by the front heating device is: (i) softened by frictional heat between the rotary tool and the steel sheets and (ii) the softened portion of the steels sheet is stirred with the rotary tool to produce plastic flow, and the welding centerline is a straight line that passes through the rotation axis of the rotary tool and is parallel to the welding direction. ### Claim 2 (depends on 1) The friction stir welding apparatus for structural steel according to claim 1, wherein, where a maximum depth of a region that extends from the surface of the steel sheets in the heated region, in a thickness direction, and has a temperature TD (° C.) satisfying TD≥0.8×TA1 (such that TA1 is described in the Formula (1)) is defined as a depth D of the heated region, the depth D of the heated region being equal to or larger than 30% of a total thickness t of the steel sheets. ### Claim 3 (depends on 1) The friction stir welding apparatus for structural steel according to claim 1, wherein the front heating device is a laser heating device. ### Claim 4 (depends on 1) The friction stir welding apparatus for structural steel according to claim 1, wherein the rear heating device is adapted to heat a welded part of the steel sheets. ### Claim 5 (depends on 4) The friction stir welding apparatus for structural steel according to claim 4, further comprising a cooling device that is provided behind the rotary tool and the rear heating device and that is adapted to cool the welded part of the steel sheets. ### Claim 6 (depends on 1) The friction stir welding apparatus for structural steel according to claim 1, further comprising a cooling device that is provided behind the rotary tool and that is adapted to cool a welded part of the steel sheets. ### Claim 7 (depends on 6) The friction stir welding apparatus for structural steel according to claim 6, wherein the rear heating device is provided behind the cooling device and is adapted to reheat the welded part of the steel sheets. ### Claim 8 (depends on 2) The friction stir welding apparatus for structural steel according to claim 2, wherein the front heating device is a laser heating device. ### Claim 9 (depends on 2) The friction stir welding apparatus for structural steel according to claim 2, wherein the rear heating device is adapted to heat a welded part of the steel sheets. ### Claim 10 (depends on 3) The friction stir welding apparatus for structural steel according to claim 3, wherein the rear heating device is adapted to heat a welded part of the steel sheets. ### Claim 11 (depends on 8) The friction stir welding apparatus for structural steel according to claim 8, wherein the rear heating device is adapted to heat a welded part of the steel sheets. ### Claim 12 (depends on 9) The friction stir welding apparatus for structural steel according to claim 9, further comprising a cooling device that is provided behind the rotary tool and the rear heating device and that is adapted to cool the welded part of the steel sheets. ### Claim 13 (depends on 10) The friction stir welding apparatus for structural steel according to claim 10, further comprising a cooling device that is provided behind the rotary tool and the rear heating device and that is adapted to cool the welded part of the steel sheets. ### Claim 14 (depends on 11) The friction stir welding apparatus for structural steel according to claim 11, further comprising a cooling device that is provided behind the rotary tool and the rear heating device and that is adapted to cool the welded part of the steel sheets. ### Claim 15 (depends on 2) The friction stir welding apparatus for structural steel according to claim 2, further comprising a cooling device that is provided behind the rotary tool and that is adapted to cool a welded part of the steel sheets. ### Claim 16 (depends on 3) The friction stir welding apparatus for structural steel according to claim 3, further comprising a cooling device that is provided behind the rotary tool and that is adapted to cool a welded part of the steel sheets. ### Claim 17 (depends on 15) The friction stir welding apparatus for structural steel according to claim 15, wherein the rear heating device is adapted to reheat the welded part of the steel sheets. ### Claim 18 (depends on 16) The friction stir welding apparatus for structural steel according to claim 16, wherein the rear heating device is adapted to reheat the welded part of the steel sheets. ### Claim 19 (depends on 8) The friction stir welding apparatus for structural steel according to claim 8, further comprising a cooling device that is provided behind the rotary tool and that is adapted to cool a welded part of the steel sheets. ### Claim 20 (depends on 19) The friction stir welding apparatus for structural steel according to claim 19, wherein the rear heating device is adapted to reheat the welded part of the steel sheets.