A high-strength high-toughness electric-resistance-welded steel pipe having high resistance to post-weld heat treatment is provided. The steel pipe having a composition including C: 0.01% to 0.12%, Si: 0.05% to 0.50%, Mn: 1.0% to 2.2%, P: 0.03% or less, S: 0.005% or less, Al: 0.001% to 0.10%, N: 0.006% or less, Nb: 0.010% to 0.100%, and Ti: 0.001% to 0.050%. The steel pipe having a structure composed of a 90% or more by volume of a bainitic ferrite phase as a main phase and 10% or less (including 0%) by volume of a second phase. The bainitic ferrite phase having an average grain size of 10 μm or less, and the structure containing fine Nb precipitates having a particle size of less than 20 nm dispersed in a base material portion. The steel pipe having high strength, toughness, and high resistance that is maintained through post-weld heat treatment.

A method for manufacturing a non-oriented electrical steel sheet according to an exemplary embodiment of the present invention includes performing hot rolling on a slab after heating the slab to manufacture a hot rolled sheet; performing hot rolled sheet annealing on the hot rolled sheet; performing cold rolling on a steel sheet on which the hot rolled sheet annealing is completed to manufacture a cold rolled sheet; and performing cold rolled sheet annealing on the cold rolled sheet in which a difference between a cold rolled sheet annealing temperature in the cold rolled sheet annealing and a hot rolled sheet annealing temperature in the hot rolled sheet annealing is 100° C. or lower.

A non-oriented electrical steel sheet according to an embodiment of the present invention includes Ti at 0.0030 wt % or less (excluding 0 wt %), Nb at 0.0035 wt % or less (excluding 0 wt %), V at 0.0040 wt % or less (excluding 0 wt %), B at 0.0003 wt % to 0.0020 wt %, and the remaining portion including Fe and other inevitably added impurities, wherein a value of ([Ti]+0.8[Nb]+0.5[V])/(10*[B]) may be 0.17 to 7.8.

The present invention relates to a process for producing a non-oriented electrical steel strip, comprising at least the following process steps (A) provision of a hot-rolled, optionally separately heat-treated, non-oriented electrical steel strip, (B) cold rolling of the electrical steel strip from step (A) to a thickness of from 0.5 to 0.8 mm in order to obtain a first cold-rolled strip, (C) intermediate heat treatment of the first cold-rolled strip from step (B) at a temperature of from 700 to 1100° C. in order to obtain an intermediate-heat-treated, first cold-rolled strip, (D) cold rolling of the intermediate-heat-treated, first cold-rolled strip from step (C) to a thickness of from 0.24 to 0.36 mm in order to obtain a second cold-rolled strip and (E) final heat treatment of the second cold-rolled strip from step (D) at a temperature of from 900 to 1100° C. in order to obtain the non-oriented electrical steel strip, a non-oriented electrical steel strip obtained in such a way and the use thereof.

The present invention manufactures a steel sheet for a rotor core for an IPM motor, wherein the steel sheet has a magnetic flux density B.sub.8000 of 1.65 T or more as measured when magnetic field strength is 8000 A/m, and a residual magnetic flux density Br of 0.5 T or more as measured at that time, and optionally, a coercivity Hc of 100 A/m or more as measured after magnetization reaches 8000 A/m. By using the steel sheet manufactured according to the present invention for a rotor core of an IPM motor, it is possible to increase further an output torque in a high-speed rotational range and raise further the maximum rotational speed.

In an Al coating layer-equipped stainless steel sheet, a base steel sheet has a predetermined chemical composition, and a total content of Fe and Cr at a first depth of an Al coating layer is 20 mass % to 70 mass %.

A metal powder capable of producing a dust core having a high saturation magnetic flux density, excellent rust resistance, and a low iron loss. The metal powder includes from 1.0% to 15.0% of Si, from 1.0% to 13.0% of Cr, from 10 ppm to 10000 ppm of Cl, from 100 ppm to 10000 ppm of S (sulfur), and from 0.2% to 7.0% of O (oxygen) by mass concentration, the remainder including Fe and unavoidable impurities, in which the average particle diameter of the metal powder is from 0.1 μm to 2.0 μm. This facilitates the production of a dust core having a high magnetic flux density, excellent rust resistance, and a low iron loss.

Provided is a method for producing a circumferential weld joint. With this method, when low-carbon martensitic stainless steel pipes used for pipelines for transportation of petroleum and natural gas are subjected to circumferential welding, the circumferential welding can be performed efficiently using a low-cost welding material having a composition similar to the composition of the low-carbon martensitic stainless steel pipes. Pipe ends of low-carbon martensitic stainless steel pipes containing prescribed components are butted against each other and subjected to multi-pass arc welding using a welding material containing prescribed components. In the first pass in the multi-pass arc welding, CMT welding is performed in which the welding material is moved back and forth against a molten pool to generate an arc intermittently. In the second and subsequent passes, one selected from GMA welding, GTA welding, and the CMT welding is performed.

Disclosed is a mar aging steel containing, in combination in mass percent, C in a content from greater than 0% to 0.02%, Mn in a content from greater than 0% to 0.3%, Si in a content from greater than 0% to 0.3%, Ni in a content of 10% to 13%, Mo in a content of 0.5% to 3.5%, Co in a content of 9% to 12%, Cr in a content of 1.5% to 4.5%, Ti in a content of 1.5% to 4.5%, and Al in a content of 0.01% to 0.2%, where the total content of Mo and Ti is 5.0 mass percent or less, and the ratio ([Mo]/[Ti]) of the Mo content [Mo] to the Ti content [Ti] is 1.0 or less, with the remainder consisting of iron and inevitable impurities.

Provided is a stainless steel powder composition, which comprises Cr, Cu, Mn, Mo, Ni and Fe; wherein, based on a total weight of the stainless steel powder composition, a content of Cr is 20 wt% to 24 wt%, and a content of Cu is more than 0 wt% and less than or equal to 0.5 wt%, a content of Mn is more than 0 wt% and less than or equal to 2 wt%, a content of Mo is 2.25 wt% to 3 wt% and a content of Ni is 10 wt% to 15 wt%. When applying the stainless steel powder composition of the present invention to laser additive manufacturing (LAM), the produced stainless steel workpiece has enhanced tensile strength, thereby expanding the follow-up applications and increasing the commercial value.