Provided is an electric resistance welded steel pipe or tube that develops no quench cracks despite having carbon content of 0.40% or more and has excellent fatigue strength. An electric resistance welded steel pipe or tube comprises: a chemical composition containing, in mass %, C: 0.40% to 0.55%, Si: 0.10% to 1.0%, Mn: 0.10% to 2.0%, P: 0.10% or less, S: 0.010% or less, Al: 0.010% to 0.100%, Cr: 0.05% to 0.30%, Ti: 0.010% to 0.050%, B: 0.0005% to 0.0030%, Ca: 0.0001% to 0.0050%, and N: 0.0005% to 0.0050%, with a balance consisting of Fe and inevitable impurities; and a ferrite decarburized layer at each of an outer surface and an inner surface, the ferrite decarburized layer having a depth of 20 ?m to 50 ?m from the surface.

A method for welding austenitic stainless steel sheets, in which welding defects do not easily occur. Austenitic stainless steel sheets each with a sheet thickness of 0.6 to 1.0 mm, which each contain, in terms of mass %, 0.08% or less of C, 1.5 to 4.0% of Si, 2.0% or less of Mn, 0.04% or less of P, 0.01% or less of S, 16.0 to 22.0% of Cr, 10.0 to 14.0% of Ni, and 0.08% or less of N, and contain at least one of Nb and Ti in an amount of 1.0% or less in total, with the rest including Fe and inevitable impurities, are overlapped and the overlapped portion is welded by arc welding. In addition, the back side of a deposited portion is cooled from 1200 C. to 900 C. at a cooling rate of 110 C./sec or higher.

An electric resistance welded steel pipe for an oil well includes in terms of mass %: 0.02 to 0.14% of C, 0.05 to 0.50% of Si, 1.0 to 2.1% of Mn, 0.020% or less of P, 0.010% or less of S, 0.010 to 0.100% of Nb, 0.010 to 0.050% of Ti, 0.010 to 0.100% of Al, and 0.0100% or less of N. Contents of Cu, Ni, Cr, Mo, V, and B are 0 to 0.50%, 0 to 1.00%, 0 to 0.50%, 0 to 0.30%, 0 to 0.10%, and 0 to 0.0030%, respectively. Remainder consisting of Fe and unavoidable impurities. In a case that a full thickness specimen is subjected to a pipe axis direction tensile test, a tensile strength is 780 MPa or more, 0.2% proof stress/tensile strength is 0.80 or more, and 2% flow stress/tensile strength is from 0.85 to 0.98.

A dual pass seam welding method for steels having a Ceq of greater than about 0.45. The first pass welds the immediately anneals the weld. On the second pass, the welder is disengaged, and the weld is subjected to a second anneal.

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.

According to the invention, a method is provided for additively manufacturing a component, in particular a metallic component, said method having the steps of: ? providing at least one substrate (I), in particular a substrate plate, the substrate being formed from one or more metallic substrate materials which has a martensite start temperature (Ms) below 140? C., the martensite start temperature (Ms) being below the manufacturing temperature (Tp); ? building the component on a building surface (5) of the substrate (I) by layered application of at least one material at a manufacturing temperature (Tp) to form a component-substrate composite (7) over a boundary surface (6); ? after building of the component (3) is complete, cooling at least the substrate (I) in the component-substrate composite (7) to a temperature below the martensite start temperature (Ms), wherein, as a result of martensitic transformation and the associated volume expansion of the metallic substrate material, a transformation stress is induced in the substrate (I), at least in the boundary surface (6) to the component (3); and ? separating the component (3) from the substrate (I). The invention further relates to a substrate (I) for use in such a method.

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.

The present invention provides a method for manufacturing a superior 13Cr friction-welded drillrod, the method comprising the following steps: manufacturing a superior 13Cr tube body; manufacturing a superior 13Cr internally threaded coupler and a superior 13Cr externally threaded coupler, respectively; connecting the superior 13Cr internally threaded coupler and the superior 13Cr externally threaded coupler respectively to the two ends of the superior 13Cr tube body by means of frictional butt welding; after heating seam areas to 950 C.-1000 C., cooling same to below 200 C. by ejecting compressed air onto the surfaces of the seam areas, and then cooling the seam areas to room temperature by spraying water; and tempering the seam areas by heating same to 640 C.-700 C. By the present method, a superior 13Cr friction-welded drillrod can be manufactured, which, in the case of the exploration of a gas filed containing a relatively high level of CO2, can be not only used as a drillrod in an earlier stage of nitrogen well-drilling operation, but also used as an oil tube in a later stage of well completion with oil tube.

A method of controlling the cooling rate of a melt pool of a powder bed includes directing a first laser beam on the powder bed to form a melt pool; coaxially aligning a second laser beam with the first laser beam; and laterally offsetting a focus spot of the second laser beam with respect to the melt pool, wherein the second laser beam heats but does not melt powder within the focus spot.

A method for repairing break of a universal connecting rod of a universal coupling includes steps of: cleaning and detecting cracks, providing primary anneal, depositing alloys, providing secondary anneal, manually milling and controlling a quality; wherein depositing the alloys includes forming gradient in an order of a bonding layer, a transition layer, a working layer and a processing layer; wherein the bonding layer: S and P in the depositing area are diluted with an FGM-KM1.sup.# material, for removing or reducing the S and P, so as to avoid cold and hot cracks; the transition layer: which is formed by an FGM-KM2.sup.# material for improving impact toughness and evacuation stress, and appropriate increasing hardness; the working layer: which is formed by an FGM-KM3.sup.# material for improving heat resistance, wear resistance and load capacity; and the processing layer: an FGM-KM4.sup.# material is used to reduce surface hardness and improve processing performance.