It is provided a mechanical structural part and a method of manufacturing the same. The mechanical structural part comprises a chemical composition containing C: 0.45% to 0.51%, Si: 0.15% to 0.35%, Mn: 0.60% to 0.90%, P: 0.030% or less, S: 0.025% or less, Al: 0.040% to 0.059%, Cr: 0.10% to 0.50%, and N: 0.0060% to 0.0100%, with the balance being Fe and inevitable impurities, and a hardened layer by induction hardening and tempering treatment, wherein an area ratio of crystal grains each having a prior austenite grain size of 80 m or less in the hardened layer is 80% or more, and a number ratio of grains each having a grain size twice or more than a mode of grain size in the hardened layer is 5% or less.

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 obtained based on a CoK characteristic X-ray diffraction result is 2.510.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 and the half-value width B of the (211) plane obtained by X-ray diffraction satisfy Formula (1).
(4.810.sup.16B+8.510.sup.16)/1.00(1)

A traverse hardening device performs traverse hardening on a shaft-like body in which a large diameter portion having a relatively large outer diameter and a small diameter portion having a relatively small outer diameter are connected via a level difference portion. The device includes: first divided coils annularly arranged around a motion center line at a first position on the motion center line; second divided coils annularly arranged around the motion center line at a second position different from the first position on the motion center line; a first divided coil drive unit configured to bring the first divided coils close to and away from the motion center line; a second divided coil drive unit configured to bring the second divided coils close to and away from the motion center line; and a control unit for the first divided coil drive unit and the second divided coil drive unit.

A traverse hardening device performs traverse hardening on a shaft-like body in which a large diameter portion having a relatively large outer diameter and a small diameter portion having a relatively small outer diameter are connected via a level difference portion. The device includes: first divided coils annularly arranged around a motion center line at a first position on the motion center line; second divided coils annularly arranged around the motion center line at a second position different from the first position on the motion center line; a first divided coil drive unit configured to bring the first divided coils close to and away from the motion center line; a second divided coil drive unit configured to bring the second divided coils close to and away from the motion center line; and a control unit for the first divided coil drive unit and the second divided coil drive unit.

traverse hardening device performs traverse hardening on a shaft-like body in which a large diameter portion and a small diameter portion are connected via a level difference portion. The device includes a plurality of divided coils which are annularly disposed around a central axis and through which a high-frequency current flows; and a coil drive unit that brings the divided coils close to and away from the central axis. Each of the divided coils includes a plurality of protruding coil portions each having a shape protruding in a direction away from the central axis, and the protruding coil portions are disposed so as to at least partially overlap each other in an extending direction of the central axis and to overlap each other in a radial direction around the central axis.

traverse hardening device performs traverse hardening on a shaft-like body in which a large diameter portion and a small diameter portion are connected via a level difference portion. The device includes a plurality of divided coils which are annularly disposed around a central axis and through which a high-frequency current flows; and a coil drive unit that brings the divided coils close to and away from the central axis. Each of the divided coils includes a plurality of protruding coil portions each having a shape protruding in a direction away from the central axis, and the protruding coil portions are disposed so as to at least partially overlap each other in an extending direction of the central axis and to overlap each other in a radial direction around the central axis.

A hollow wind turbine main shaft and a profiling forging process and a use thereof are provided. The profiling forging process includes: step S1: smelting alloying elements according to a formula to obtain a melt, casting the melt to obtain an ingot, and hot-feeding the ingot; step S2: reheating the ingot hot-fed in the step S1, followed by primary drawing-out, primary upsetting, secondary drawing-out, and secondary upsetting to obtain a forged ingot; step S3: reheating the forged ingot, followed by punching to obtain a punched forging; step S4: reheating the punched forging, and performing drawing-out and rounding on a shaft body of the punched forging to obtain a finished forging; and step S5: placing the finished forging into a thermal insulation barrel for slow cooling, and air-cooling the finished forging to a room temperature to obtain the hollow wind turbine main shaft.

A hollow wind turbine main shaft and a profiling forging process and a use thereof are provided. The profiling forging process includes: step S1: smelting alloying elements according to a formula to obtain a melt, casting the melt to obtain an ingot, and hot-feeding the ingot; step S2: reheating the ingot hot-fed in the step S1, followed by primary drawing-out, primary upsetting, secondary drawing-out, and secondary upsetting to obtain a forged ingot; step S3: reheating the forged ingot, followed by punching to obtain a punched forging; step S4: reheating the punched forging, and performing drawing-out and rounding on a shaft body of the punched forging to obtain a finished forging; and step S5: placing the finished forging into a thermal insulation barrel for slow cooling, and air-cooling the finished forging to a room temperature to obtain the hollow wind turbine main shaft.