The railway axle according to this disclosure has a pair of fitting portions and which each include a fitting portion hardened layer and a base metal portion, and a center parallel portion which includes a center parallel portion hardened layer and the base metal portion. The base metal portion has the chemical composition described in the description. In a region having the Vickers hardness of 480 HV or more in the center parallel portion hardened layer, a dislocation density p obtained based on a CoKα characteristic X-ray diffraction result is 2.5×10.sup.16 m.sup.−2 or less, a half-value width B of the (211) diffraction plane is 1.34 degrees or less, and the dislocation density p and the half-value width B of the (211) plane obtained by X-ray diffraction satisfy Formula (1).

(−4.8×10.sup.16×B+8.5×10.sup.16)/ρ≥1.00  (1)

A method for manufacturing a magnetostrictive torque sensor shaft (100) to which a sensor portion (2) of a magnetostrictive torque sensor (1) is to be attached includes: a heat treatment step of subjecting an iron-based shaft member to a carburizing, quenching, and tempering process; a shot peening step of performing shot peening using a steel shot media having a Vickers hardness at least equal to 1100 and at most equal to 1300, at least in a position on the shaft member, after the heat treatment step, to which the sensor portion (2) is to be attached; and a surface polishing step of subjecting the shaft member after the shot peening to surface polishing.

A method for manufacturing a magnetostrictive torque sensor shaft (100) to which a sensor portion (2) of a magnetostrictive torque sensor (1) is to be attached includes: a heat treatment step of subjecting an iron-based shaft member to a carburizing, quenching, and tempering process; a shot peening step of performing shot peening using a steel shot media having a Vickers hardness at least equal to 1100 and at most equal to 1300, at least in a position on the shaft member, after the heat treatment step, to which the sensor portion (2) is to be attached; and a surface polishing step of subjecting the shaft member after the shot peening to surface polishing.

A method for producing a machine component excellent in pitting resistance characteristics and toughness includes a carburizing step, performed on a steel material containing 0.13-0.30% C and 0.90-2.00% Cr in mass % and at least one of Si, Mn, Ni, Mo, Nb, V, Ti, B, Al, and N, balance Fe and unavoidable impurities; heating the material to 850-1030° C. to attain carbon concentration in a surface of 0.8-1.5%; cooling the material at an average rate of 5° C./sec or lower from a temperature higher than the A.sub.cm point of a surface layer to a cooling end temperature that is at least 50° C. lower than the A.sub.1 point to cause the surface layer to have a pearlite or bainite structure with dispersion; spheroidizing annealing at a temperature not higher than the A.sub.cm point at the surface layer; heating the material to not higher than the A.sub.cm point at the surface layer; and performing tempering.

A method of manufacturing a magnetostrictive torque sensor shaft (100) to which a sensor portion (2) of a magnetostrictive torque sensor (1) is mounted. The method includes heat treatment step of subjecting an iron-based shaft member to a carburizing, quenching, and tempering process, and a shot peening step of performing shot peening using a steel shot media having a Vickers hardness at least equal to 1100 and at most equal to 1300 and being free of boron, at least in a position on the shaft member, after the heat treatment step, to which the sensor portion is to be attached.

An apparatus for backward flow forming a material may comprise a mandrel having a headstock at a proximate end of the mandrel, the mandrel configured to rotate about an axis, a plurality of rollers disposed radially outward of the mandrel configured to exert force on the material to form a work piece at a plastic deformation zone, wherein the work piece flows from the plastic deformation zone between the plurality of rollers and the mandrel toward a distal end of the mandrel, and a catcher, coaxial to the mandrel, and removably coupled to the work piece at a traveling end of the work piece.

An oil-immersion quenching cooling precursor and an oil-immersion quenching cooling method includes an axle-type workpiece or a workpiece that has sections in an axle form. Several separation rings are arranged on the workpiece in the axial direction to separate the axle-type workpiece or the workpiece that has sections in an axle form into a plurality of sections before oil-immersion quenching cooling. In the method, there is a cutting procedure before a quenching cooling procedure. Several separation rings distributed in the axial direction are reserved outside a dimension required for the workpiece. sections before oil-immersion quenching cooling. In the method, there is a cutting procedure before a quenching cooling procedure. Several separation rings distributed in the axial direction are reserved outside a dimension required for the workpiece.

An oil-immersion quenching cooling precursor and an oil-immersion quenching cooling method includes an axle-type workpiece or a workpiece that has sections in an axle form. Several separation rings are arranged on the workpiece in the axial direction to separate the axle-type workpiece or the workpiece that has sections in an axle form into a plurality of sections before oil-immersion quenching cooling. In the method, there is a cutting procedure before a quenching cooling procedure. Several separation rings distributed in the axial direction are reserved outside a dimension required for the workpiece. sections before oil-immersion quenching cooling. In the method, there is a cutting procedure before a quenching cooling procedure. Several separation rings distributed in the axial direction are reserved outside a dimension required for the workpiece.

The present invention belongs to the field of mechanical engineering and materials, more specifically in the metallurgy segments, for application in the sugar industry. The invention relates to the hot forging process of mill shafts and heat-treated auxiliary equipment in CrNiMo and low carbon alloy. The shafts and auxiliary equipment manufactured according to this invention have a long service life, thus reducing downtime for maintenance and increasing reliability, since it eliminates the problems associated with cracks and instantaneous fractures. As a consequence, there is a reduction in the risks of accidents and production losses associated with stoppages.

The present invention belongs to the field of mechanical engineering and materials, more specifically in the metallurgy segments, for application in the sugar industry. The invention relates to the hot forging process of mill shafts and heat-treated auxiliary equipment in CrNiMo and low carbon alloy. The shafts and auxiliary equipment manufactured according to this invention have a long service life, thus reducing downtime for maintenance and increasing reliability, since it eliminates the problems associated with cracks and instantaneous fractures. As a consequence, there is a reduction in the risks of accidents and production losses associated with stoppages.