Abstract: A piercer plug with increased life and a method of manufacturing it are provided. The piercer plug 1 includes a tip portion 2 and a trunk portion 3 made of the same material as the tip portion 2 and continuous to the tip portion 2. The trunk portion 3 includes a cylindrical portion 5 having a hole used for attaching a bar. The tip portion 2 is harder than the cylindrical portion 5.

Abstract: A piercer plug with increased wear resistance is provided. A piercer plug includes: a plug body; and a sprayed coating formed on the surface of the plug body. The sprayed coating contains an iron-based alloy and oxides thereof. The chromium concentration determined by analyzing the sprayed coating with X-ray fluorescence analysis is 3 to 20 mass %.

Abstract: A piercer plug having good base-material deformation resistance is provided. A method of manufacturing a piercer plug (10) includes the steps of; preparing a plug body (1) including a tip portion (11) and a cylindrical portion (12) having a hole (121) usable to attach a bar and located rearward of the tip portion (11); forming a build-up layer (2) on the surface of the tip portion (11); and heating the plug body (1) such that the temperature of the tip portion (11) with the build-up layer (2) formed thereon is not lower than the austenite transformation temperature and the temperature of the cylindrical portion (12) is lower than the austenite transformation temperature.

Abstract: A piercing plug includes a plug main body, and a sprayed coating which is formed on a surface of the plug main body and includes iron and iron oxide. A chemical composition of the sprayed coating includes, in addition to the iron and the iron oxide, by mass %, C: 0.015% to 0.6%, Si: 0.05% to 0.5%, Mn: 0.1% to 1.0%, and Cu: 0 to 0.3%.

Abstract: A piercer plug having good base-material deformation resistance is provided. A method of manufacturing a piercer plug (10) includes the steps of; preparing a plug body (1) including a tip portion (11) and a cylindrical portion (12) having a hole (121) usable to attach a bar and located rearward of the tip portion (11); forming a build-up layer (2) on the surface of the tip portion (11); and heating the plug body (1) such that the temperature of the tip portion (11) with the build-up layer (2) formed thereon is not lower than the austenite transformation temperature and the temperature of the cylindrical portion (12) is lower than the austenite transformation temperature.

Abstract: A piercer plug with increased life and a method of manufacturing it are provided. The piercer plug 1 includes a tip portion 2 and a trunk portion 3 made of the same material as the tip portion 2 and continuous to the tip portion 2. The trunk portion 3 includes a cylindrical portion 5 having a hole used for attaching a bar. The tip portion 2 is harder than the cylindrical portion 5.

Abstract: A piercing plug of the present invention includes: a plug body; a Ni—Cr layer formed on a surface of the plug body; and a sprayed coating formed on a surface of the Ni—Cr layer. The plug body contains, by mass %, 20 to 30% of Cr, 30 to 55% of Ni, 0.005 to 0.5% of C, 0.1 to 1.0% of Si, 0.2 to 1.5% of Mn, and at least one of Mo and W which satisfy a following conditional expression (A), and remainder including Fe and impurities. 1.5%?Mo+0.5W?8.

Abstract: A plug that achieves prevention of peel-off of the coating and a method of manufacturing such a plug are provided. A plug (10) is used for piercing a billet. The plug (10) includes a plug body (1), a body coating (2), and a surface-layer coating (3). The body coating (2) is provided on a surface of the plug body. The body coating (2) contains iron and iron oxides. The surface-layer coating (3) is provided on the body coating (2). The surface-layer coating (3) contains iron and iron oxides. The surface-layer coating (3) has a porosity lower than that of a region of the body coating (2) adjacent to the surface-layer coating (3) and having a thickness equal to that of the surface-layer coating (3).

Abstract: Provided is a method for producing a plug for use in a piercing-rolling mill for producing a seamless steel tube/pipe, and the method for producing the plug for piercing-rolling comprises shotblasting a surface of the plug, and arc-spraying a spray wire so as to form a film on a surface of a base metal of the plug that is shotblasted. In the arc-spraying step, the arc spraying is carried out by using, as the spray wire, a cored wire whose iron sheath tube is charged with at least iron oxide particles among iron particles and the iron oxide particles (one or more of FeO particles, Fe3O4 particles, and Fe2O3 particles), so as to form the film containing iron oxide and Fe. Accordingly, it is possible to enhance the production efficiency of the plug, and to produce the plug for piercing-rolling capable of securing the steady enhancement of the durability life of the plug during the piercing-rolling.

Abstract: A method for producing a plug includes: a step of preparing a plug base metal having a concave portion along a circumferential direction in an outer peripheral surface; and an arc spraying step of spraying a spraying wire rod material onto the outer peripheral surface of the plug base metal by arc spraying to form films containing Fe and Fe oxides on the outer peripheral surface of the plug base metal. The arc spraying step includes: a separating step of separating the outer peripheral surface of the plug base metal into a plurality of regions along an axial direction; and a step of performing arc spraying separately in each of the regions. In the separating step, a boundary between the regions is set at the concave portion. In this way, peeling of films at a connecting portion is prevented, and the lifetime of the plug can be increased.

Abstract: Provided is an equipment system for producing a piercing-rolling plug to be used for producing a seamless steel tube/pipe, which includes a shotblasting device for applying shotblasting on a surface of the plug, and an arc-spraying device for performing arc-spraying of iron wires on a surface of a base metal of the plug to which the shotblasting is applied, so as to form a film containing oxide and Fe thereon. The arc-spraying device includes plural spraying booths each of which separately forms part of the film in turn in each of sections into which the surface of the base metal of the plug is divided along an axial direction of the plug. The production efficiency of the plug can therefore be maintained at a high level, and steady enhancement of the durability life of the plug can be realized during the piercing-rolling.

Abstract: It is an objective to provide a plug capable of enhancing a usage count of the plug, which is for use in a piercing machine for piercing-rolling a billet, and a regenerating method of the plug. The plug (10) is for use in a piercing machine (30) for piercing-rolling a billet (36). The plug (10) includes a body (18), a columnar portion (20), and a sprayed film (16). The body (18) has a maximum diameter at its rear end. The columnar portion (20) has the same diameter as the diameter of the rear end of the body (18), and extends from the rear end of the body (18). The sprayed film (16) is formed on a surface of the body (18) and on a surface of the columnar portion (20).

Abstract: A plug for hot tube-making includes: a plug main body; a build-up layer formed around an axis of the plug main body on a surface of the plug main body; and a sprayed coating formed on a surface of the build-up layer.

Abstract: To increase the life of a plug used in a piercing machine for piercing-rolling a billet. The plug (10) is used in a piercing machine (30) that piercing-rolls a billet (36). The plug (10) includes a plug body (12), a build-up layer (14), and a sprayed film (16). The build-up layer (14) is formed on a surface of the plug body (12). The sprayed film (16) covers at least an area ranging from the rear end of the build-up layer (14) to a position of the maximum outer diameter of the plug body (12).

Abstract: A stainless steel member comprising a stainless steel base metal; an oxide film located on the surface of the stainless steel base metal; an electroconductive layer located on the surface of the oxide film and comprising a nonmetallic electroconductive material; and an electroconductive material which is located so as to penetrate the oxide film and which electrically contacts the stainless steel base metal and the electroconductive layer is provided as a stainless steel member for a separator of a solid polymer fuel cell having excellent properties such that a degradation in performance is low even after prolonged operation. A solid polymer fuel cell using the stainless steel member is also provided.

Abstract: A piercing plug includes a plug main body, and a sprayed coating which is formed on a surface of the plug main body and includes iron and iron oxide. A chemical composition of the sprayed coating includes, in addition to the iron and the iron oxide, by mass %, C: 0.015% to 0.6%, Si: 0.05% to 0.5%, Mn: 0.1% to 1.0%, and Cu: 0 to 0.3%.

Abstract: A piercing plug of the present invention includes: a plug body; a Ni—Cr layer formed on a surface of the plug body; and a sprayed coating formed on a surface of the Ni—Cr layer. The plug body contains, by mass %, 20 to 30% of Cr, 30 to 55% of Ni, 0.005 to 0.5% of C, 0.1 to 1.0% of Si, 0.2 to 1.5% of Mn, and at least one of Mo and W which satisfy a following conditional expression (A), and remainder including Fe and impurities. 1.5%?Mo+0.5 W?8.

Abstract: A plug for hot tube-making includes: a plug main body; a build-up layer formed around an axis of the plug main body on a surface of the plug, main body, and a sprayed coating formed on a surface of the build-up layer.

Abstract: A method for producing a plug for use in a piercing-rolling mill for producing a seamless steel tube/pipe includes a step of carrying out shotblasting on a surface of the plug, and an arc-spraying step of performing arc-spraying of a spray wire to form a film on a surface of a base metal of the plug to which the shotblasting is applied. In the arc-spraying step, arc-spraying uses a cored wire whose iron sheath tube is filled with at least low-thermal conductive particles like ZrO2 particles, which have lower thermal conductivity than that of iron oxide among iron particles and low-thermal conductive particles, to form the film containing iron oxide, Fe and low-thermal conductive material. The formed film has enhanced insulation performance to produce the plug capable of ensuring the steady enhancement of the durability life of the plug during the piercing-rolling.

Abstract: Provided is a method for producing a plug for use in a piercing-rolling mill for producing a seamless steel tube/pipe, and the method for producing the plug for piercing-rolling comprises shotblasting a surface of the plug, and arc-spraying a spray wire so as to form a film on a surface of a base metal of the plug that is shotblasted. In the arc-spraying step, the arc spraying is carried out by using, as the spray wire, a cored wire whose iron sheath tube is charged with at least iron oxide particles among iron particles and the iron oxide particles (one or more of FeO particles, Fe3O4 particles, and Fe2O3 particles), so as to form the film containing iron oxide and Fe. Accordingly, it is possible to enhance the production efficiency of the plug, and to produce the plug for piercing-rolling capable of securing the steady enhancement of the durability life of the plug during the piercing-rolling.