A friction stir welding apparatus includes a FSW tool that is held by a housing and welds to-be-welded members to each other by friction stir, and a gradual cooling device that gradually cools a weld site of the to-be-welded members welded by the FSW tool. The gradual cooling device is a contactless heat source that heats the weld site without coming into contact with the weld site. The contactless heat source is a high-frequency heat source.

Provided is an AlFe-alloy plated steel sheet for hot forming, having excellent TWB welding characteristics since excellent hardness uniformity of a TWB weld zone after hot forming is obtained by suitably controlling a batch annealing condition, after plating Al, such that an AlFe-alloy layer is formed; a hot forming member; and manufacturing methods therefor.

A method for producing a welded blank (1) includes providing two precoated sheets (2), butt welding the precoated sheets (2) using a filler wire. The precoating (5) entirely covers at least one face (4) of each sheet (2) at the time of butt welding. The filler wire (20) has a carbon content between 0.01 wt. % and 0.45 wt. %. The composition of the filler wire (20) and the proportion of filler wire (20) added to the weld pool is chosen such that the weld joint (22) has (a) a quenching factor FT.sub.WJ: FT.sub.WJ?0.9FT.sub.BM?0, where FT.sub.BM is a quenching factor of the least hardenable substrate (3), and FT.sub.WJ and FT.sub.BM are determined: FT=128+1553?C+55?Mn+267?Si+49?Ni+5?Cr?79?Al?2?Ni.sup.2?1532?C.sup.2?5?Mn.sup.2?127?Si.sup.2?40?C?Ni?4?Ni?Mn, and (b) a carbon content C.sub.WJ<0.15 wt. % or, if C.sub.WJ?0.15 wt. %, a softening factor FA.sub.WJ such that FA.sub.WJ>5000, where FA=10291+4384.1?Mo+3676.9Si?522.64?Al?2221.2?Cr?118.11?Ni?1565.1?C?246.67?Mn.

Embodiments of the present disclosure are directed to coiled steel tubes and methods of manufacturing coiled steel tubes. In some embodiments, the final microstructures of the coiled steel tubes across all base metal regions, weld joints, and heat affected zones can be homogeneous. Further, the final microstructure of the coiled steel tube can be a mixture of tempered martensite and bainite.

Embodiments of the present disclosure are directed to coiled steel tubes and methods of manufacturing coiled steel tubes. In some embodiments, the final microstructures of the coiled steel tubes across all base metal regions, weld joints, and heat affected zones can be homogeneous. Further, the final microstructure of the coiled steel tube can be a mixture of tempered martensite and bainite.

A brazed joint having excellent tensile strength (TSS and CTS) and a method of production of the same are provided. A sheet combination 200 comprised of steel sheets 210, 220 between which a brazing filler metal 230 is clamped is heated at a temperature of the Ac3 point of the steel sheet (matrix material) or more. The Ar3 point of the regions near the brazing filler metal at the steel sheets is made higher than the Ar3 point of the steel sheets (matrix material), then the quenching start temperature X is made a temperature of the Ar3 point of the steel sheet (matrix material) or less and hot stamping is performed to produce a brazed joint.

A welded steel part with a very high mechanical strength is provided. The welded steel part is obtained by heating followed by hot forming, then cooling of at least one welded blank obtained by butt welding of at least one first and one second sheet. The at least one first and second sheets including, at least in part, a steel substrate and a pre-coating which includes an intermetallic alloy layer in contact with the steel substrate, topped by a metal alloy layer of aluminum or aluminum-based alloy. A method for the fabrication of a welded steel part and the fabrication of structural or safety parts for automotive vehicles are also provided.

A steel plate comprising, by mass %: C: 0.03% to 0.12%, Si: 0.5% or less, Mn: 1.0% to 2.0%, P: 0.015% or less, S: 0.0005% to 0.0050%, Al: 0.005% to 0.060%, Ni: 0.5% to 2.0%, Ti: 0.005% to 0.030%, N: 0.0015% to 0.0065%, O: 0.0010% to 0.0050%, Ca: 0.0005% to 0.0060%, and optionally one or two or more of Cu and the like. Ti/N, Ceq, Pcm, and ACR are in particular ranges, a base metal of the plate has an effective grain size of 20 m or less at half the thickness of the plate, and the plate contains a particular number of complex inclusions at and of the thickness of the plate. The complex inclusions comprise a sulfide containing Ca and Mn and an oxide containing Al and having an equivalent circular diameter of 0.1 m or more.

A tool system for stress relieving a turbocharger turbine wheel longitudinally welded to a hardened rotor shaft. The shaft has a journal bearing region and a turbine-end body forming an A datum surface for receiving an axial bearing. The tool system includes an induction coil and an electronic oscillator, and a tool. The tool forms an opening configured to receive the rotor shaft such that the journal bearing region of the shaft extends into the tool housing while the A datum surface adjoins an end of the tool housing. The induction coil is positioned around the turbine-end body. The housing forms an annular cooling chamber surrounding the journal bearing region of the shaft. The housing forms an inlet passage to provide cooling fluid to the annular chamber, and an outlet passage to remove cooling fluid from the annular chamber.

The invention relates to a method for producing an at least partially hardened profiled component and to a corresponding semi-finished product (1) which simplifies the development process and reduces the investment costs in production machines. At first, a first profiled segment (19), which has a uniform cross-sectional shape (9, 10) along its extent (22), and a second profiled segment (20), which has a non-uniform cross-sectional shape (9, 10) along its extent (22), are joined together at a joining point (6) in order to form at least part of a semi-finished product (1). At the joining point (6), the first and the second profiled segments (19, 20) have cross-sectional shapes (9, 10) which substantially correspond with one another. After heating (25) to a hardening temperature, the semi-finished product (1) is formed in a forming tool (11) by means of internal high-pressure forming (26) or pressing to produce the profiled component (2) which, after the forming (26) within the forming tool (11), is hardened by quenching (27).