A method of friction-stir welding, FSW, ajoint J, for example a T joint and/or a lap joint, between a first workpiece W1 and a second workpiece W2, is described. The method comprises: performing a first pass P1 of FSW of the joint J by moving therealong a first tool (10), comprising a first probe (100) rotating in a first rotational direction RD1, in a first movement direction MD1 defining a first line L1, on a first side S1 of the joint J, comprising: inserting the first probe (100) to a first depth D1, thereby providing a first welded region WR1; withdrawing at least partially the first probe (100), thereby providing a first partially welded and/or unwelded region PWUR1; and fully withdrawing the first probe (100), thereby resulting in a first exit hole EXH1; performing a second pass P2 of FSW of the joint J by moving therealong a second tool (20), comprising a second probe (200) rotating in a second rotational direction RD2, in a second movement direction MD2 defining a second line L2, on the first side S1 of the joint J, comprising: inserting the second probe (200) to a second depth D2, thereby providing a second welded region WR2; optionally withdrawing at least partially the second probe (200); and fully withdrawing the second probe 200, thereby resulting in a second exit hole EXH2; wherein the second welded region WR2 includes the first exit hole EXH1; and wherein the second exit hole EXH2 is included in the first welded region WR1.

A method of friction-stir welding, FSW, ajoint J, for example a T joint and/or a lap joint, between a first workpiece W1 and a second workpiece W2, is described. The method comprises: performing a first pass P1 of FSW of the joint J by moving therealong a first tool (10), comprising a first probe (100) rotating in a first rotational direction RD1, in a first movement direction MD1 defining a first line L1, on a first side S1 of the joint J, comprising: inserting the first probe (100) to a first depth D1, thereby providing a first welded region WR1; withdrawing at least partially the first probe (100), thereby providing a first partially welded and/or unwelded region PWUR1; and fully withdrawing the first probe (100), thereby resulting in a first exit hole EXH1; performing a second pass P2 of FSW of the joint J by moving therealong a second tool (20), comprising a second probe (200) rotating in a second rotational direction RD2, in a second movement direction MD2 defining a second line L2, on the first side S1 of the joint J, comprising: inserting the second probe (200) to a second depth D2, thereby providing a second welded region WR2; optionally withdrawing at least partially the second probe (200); and fully withdrawing the second probe 200, thereby resulting in a second exit hole EXH2; wherein the second welded region WR2 includes the first exit hole EXH1; and wherein the second exit hole EXH2 is included in the first welded region WR1.

A method of friction-stir welding, FSW, a joint J, for example a T joint J, between a first workpiece W1 and a second workpiece W2 is described. The method comprises: arranging the first workpiece W1 and the second workpiece W2; performing a first pass P1 of FSW of the joint J by moving therealong a first tool 10, comprising a first probe 100 rotating in a first rotational direction RD1 and at least partially inserted into the first workpiece W1 and/or into the second workpiece W2 to a first depth D1, in a first movement direction MD1 defining a first line L1, on a first side S1 of the joint J, thereby providing a first welded region WR1; and performing a second pass P2 of FSW of the joint J by moving therealong a second tool 20, comprising a second probe 200 rotating in a second rotational direction RD2 and at least partially inserted into the first workpiece W1 and/or into the second workpiece W2 to a second depth D2, in a second movement direction MD2 defining a second line L2, on a second side S2 of the joint J, thereby providing a second welded region WR2; wherein the first tool 10 and the second tool 20 are mutually opposed; and wherein performing the first pass P1 of FSW and performing the second pass P2 of FSW are at least partially concurrent.

The present invention includes: a primary joining process in which a coarse portion having a predetermined width is formed in the vicinity of a step side face within a plasticized region while the rotary tool is being moved one round along a first butted portion to perform friction stirring in a state that a tip of a tip side pin of a rotary tool being rotated is inserted to the same depth as or slightly deeper than a step bottom face and an outer circumferential face of a base side pin is in contact with a front face of a sealing body and the tip side pin is slightly in contact with at least an upper portion of a jacket body and an inspection process in which a passed position of the tip side pin is specified by performing, a flaw detection to detect the coarse portion.

The present invention provides a process for suppressing abnormal grain growth in friction stir welded aluminum alloys by inserting an intermediate annealing treatment (“IAT”) after the welding step on the article. The IAT may be followed by a solution heat treatment (SHT) on the article under effectively high solution heat treatment conditions. In at least some embodiments, a deformation step is conducted on the article under effective spin-forming deformation conditions or under effective superplastic deformation conditions. The invention further provides a welded article having suppressed abnormal grain growth, prepared by the process above. Preferably the article is characterized with greater than about 90% reduction in area fraction abnormal grain growth in any friction-stir-welded nugget.

A method of forming an assembly in which a metal extension element is connected with a metal stub element, by an intermediate element. The intermediate element extends between first and second ends. The intermediate element is positioned to locate its first end spaced apart from the stub element. An inner end of the extension element is spaced apart from the second end of the intermediate element. Heating elements are located between the elements, to heat the proximal portions of the elements to a hot working temperature, at which the heated portions are subject to plastic deformation. The heating elements are removed, and while the intermediate element is rotating, the first end is urged against the stub element to bond the intermediate element with the stub element. While the extension element is rotating, the inner end is urged against the second end to bond the extension element and the intermediate element.

A method of forming an assembly in which a metal extension element is connected with a metal stub element, by an intermediate element. The intermediate element extends between first and second ends. The intermediate element is positioned to locate its first end spaced apart from the stub element. An inner end of the extension element is spaced apart from the second end of the intermediate element. Heating elements are located between the elements, to heat the proximal portions of the elements to a hot working temperature, at which the heated portions are subject to plastic deformation. The heating elements are removed, and while the intermediate element is rotating, the first end is urged against the stub element to bond the intermediate element with the stub element. While the extension element is rotating, the inner end is urged against the second end to bond the extension element and the intermediate element.

A fastening element for friction welding onto a planar workpiece includes a nut head, a through-bore extending at least locally within the nut head, a friction welding face on one end side of the nut head, and a cutting device for introducing a drilled hole into the workpiece on the one end side of the nut head having the friction welding face.

A method may comprise: placing a probe in a molten metal melt comprising a thixotropic metal alloy; injecting a gas into the molten metal melt to form a saturated slurry, the saturated slurry being at a temperature above a liquidus temperature of the thixotropic metal alloy after injecting the gas; removing the probe from the molten metal melt; and depositing the molten metal melt through an extruder of an additive manufacturing system.

A subassembly includes a wheel hub and a constant velocity joint having a bell in which the wheel hub is connected to the bell by friction welding. A first one of the wheel hub and the bell may include an axial projection and the other one of the wheel hub and the bell may include a recess in which the axial projection is received. Also a method of connecting a wheel hub to a constant velocity joint by friction welding.