Disclosed is a cold forged gear steel. In addition to Fe and inevitable impurities, the cold forged gear steel further comprises the following chemical elements in mass percentage: 0.15-0.17% of C, 0.10-0.20% of Si, 1.0-1.10% of Mn, 0.80-0.90% of Cr and 0.02-0.04% of Al. Correspondingly, further disclosed is a manufacturing method for the cold forged gear steel, comprising the steps of: (1) smelting and casting; (2) heating; (3) forging or rolling; and (4) spheroidizing annealing: heating to and keeping at 750-770? C., then cooling with a cooling rate of 5-15? C./h to and keeping at 700-720? C., cooling with a cooling rate of 3-12? C./h to and keeping at 660-680? C., and cooling with a cooling rate of 5-20? C./h to 500? C. or below, and then tapping and cooling.

The invention relates to a device for treating, by heat tempering, a metal element (1) of the tube or bar type having arched portions. The device includes heat treatment means having an induction coil (23) and a sprinkler ring (26). According to the invention, this device includes means (2) for holding the metal element (1) that is composed of a clip (2) arranged so as to clamp around an end portion, referred to as the top, of the metal element and to keep the metal element freely suspended under said clip. The device also includes multi-axis robots (24, 28) suitable for moving the induction coil (23) and the sprinkler ring (26) simultaneously along the metal element (1) starting from an end portion, referred to as the bottom, of the metal element that is opposite the top portion thereof.

Embodiments of an ultra-fine-grained, medium carbon steel are disclosed herein. In some embodiments, the ultra-fine grained steel can have high corrosion fatigue resistance, as well as high toughness and yield strength. The ultra-fine grained steels can be advantageous for use as sucker rods in oil wells having corrosive environments.

Provided is a method for manufacturing a magnetostrictive torque sensor shaft mounting a sensor portion of a magnetostrictive torque sensor. The method includes conducting heat treatment on a shaft material including chrome steel or chrome-molybdenum steel by carburizing, quenching and tempering, and conducting shot peening on the shaft material after the heat treatment at least on a position where the sensor portion is to be mounted. The shot peening is conducted by firing shot with a particle size of not less than 0.6 mm and a Rockwell hardness of not less than 60 at a jet pressure of not less than 0.4 MPa for a jet exposure time of not less than 2 minutes.

Provided is a high frequency induction heating apparatus capable of quenching a workpiece having an outward flange, over the whole circumference by means of a frequency with which a penetration depth of an electromagnetic wave is larger than a sheet thickness of the workpiece The high frequency induction heating apparatus includes a high frequency induction heating coil used for heating a long hollow steel workpiece having a closed cross section and an outward flange, in 3DQ in which a bending member is manufactured from the workpiece The high frequency induction heating coil includes a magnetic material core facing each other between which both faces of the outward flange are interposed, having a distance from both faces, and an induction heating coil connected to the magnetic material core and arranged surrounding an outer circumference of a general portion where the outward flange is excluded from the workpiece.

A rolled round steel material contains C: 0.38 to 0.55%, Si: 1.0% or less, Mn: 0.20 to 2.0%, S: 0.005 to 0.10%, Cr: 0.01 to 2.0%, Al: 0.003 to 0.10%, B: 0.0005 to 0.0030%, Ti: 0.047% or less, Cu: 0 to 1.0%, Ni: 0 to 3.0%, Mo: 0 to 0.50%, Nb: 0 to 0.10%, V: 0 to 0.30%, Ca: 0 to 0.005%, and Pb: 0 to 0.30%, a remaining portion being constituted by Fe and an impurities, the impurities containing P in an amount of 0.030% or less and N in an amount of 0.008% or less, and has a chemical composition satisfying [3.4NTi3.4N+0.02]. The microstructure is constituted by ferrite (F), lamellar pearlite (LP), and cementite (C) and microstructural features vary in terms of the lateral, longitudinal and central portions of the steel. This steel material has a high base material toughness and good machinability without performing thermal refining.

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.

One aspect of the present disclosure is directed to low-alloy steels exhibiting high hardness and an advantageous level of multi-hit ballistic resistance with minimal crack propagation imparting a level of ballistic performance suitable for military armor applications. Certain embodiments of the steels according to the present disclosure have hardness in excess of 550 HBN and demonstrate a high level of ballistic penetration resistance relative to conventional military specifications.

A bainitic steel comprising, in weight % (wt %) C: 0.16-0.23, Si: 0.8-1.0, Mo: 0.67-0.9, Cr: 1.10-1.30, V: 0.18-0.4, Ni: 1.60-2.0, Mn: 0.65-0.9, P: 50.020, S: 50.02, Cu: <0.20, N: 0.005-0.012, balance Fe and unavoidable impurities.

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 boron-free zirconia 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 is to be attached. The surface of the shaft member, after shot peening, has a total error, including hysteresis error and angle error, of not more than 3%.