Systems and methods for locally softening high strength steel are disclosed. One method may include heat treating one or more local regions of a steel component having a hardness of at least 450 HV to soften the local region(s) to a hardness of at most 250 HV. The heat treating may include heating only the local region(s) to a target temperature above an A.sub.C1 temperature of the component and below an A.sub.C3 temperature of the component. In another method, the heat treating may include heating only the local region(s) to a first target temperature above an A.sub.C3 temperature of the component, cooling the local region(s) to below an A.sub.C1 temperature of the component, and isothermally holding the local region(s) at a second target temperature below the A.sub.C1 temperature. The locally softened region(s) may allow for improved joining and/or trimming of the component.

A track link which is a tracked undercarriage component is made of a steel having a specific component composition, and includes a high hardness portion having a hardness of HRC 57 or more and HRC 60 or less, and a low hardness portion. The high hardness portion includes a first matrix including a martensite phase and a residual austenite phase, and first nonmetallic particles dispersed in the first matrix and including at least one species selected from the group consisting of MnS, TiCN, and NbCN, and it does not include a M.sub.23C.sub.6 carbide. The low hardness portion includes a second matrix including a martensite phase, and second nonmetallic particles dispersed in the second matrix and including at least one species selected from the group consisting of MnS, TiCN, and NbCN, and it does not include a M.sub.23C.sub.6 carbide.

A track link which is a tracked undercarriage component is made of a steel having a specific component composition, and includes a high hardness portion having a hardness of HRC 57 or more and HRC 60 or less, and a low hardness portion. The high hardness portion includes a first matrix including a martensite phase and a residual austenite phase, and first nonmetallic particles dispersed in the first matrix and including at least one species selected from the group consisting of MnS, TiCN, and NbCN, and it does not include a M.sub.23C.sub.6 carbide. The low hardness portion includes a second matrix including a martensite phase, and second nonmetallic particles dispersed in the second matrix and including at least one species selected from the group consisting of MnS, TiCN, and NbCN, and it does not include a M.sub.23C.sub.6 carbide.

Provided is a mechanical structural member that can reduce deformation and has high precision and excellent quality. The mechanical structural member has a groove (32) and a tooth (33) formed by plastic working, and includes a hardened layer (31a) with a uniform martensitic single phase structure formed on a surface by induction hardening, a core region (31b) having a sorbite structure, and a boundary layer (31c) in which a sorbite structure and a martensite structure are mixed, formed between the core region (31b) and the hardened layer (31a). Rockwell hardness in the core region is 13 to 28 (HRC), and a variation in the Rockwell hardness is within 6 (HRC).

A hot-press molding method of the present disclosure includes a first heating process in which a steel plate is heated and the entire steel plate becomes austenite, a first cooling process in which a cooling rate of the steel plate after the first heating process is partially changed, a first region which is a part of the steel plate is transformed into martensite, and a second region other than the first region remains as austenite, a second heating process in which the entire steel plate is reheated and the first region becomes tempered martensite, and a second cooling process in which the entire steel plate after the second heating process is cooled. At least one of the first cooling process and the second cooling process is performed during a molding process in which the steel plate is press-molded on a molding die.

When welding with a consumable wire electrode, current contacting occurs when the electrode wire passes by a readily electrically conductive contact element. In order to improve the current contacting and reduce the wear of the contact element in particular, the invention proposes subjecting contact elements to a cold treatment prior to using same. The cold treatment has a cooling phase during which the temperature of the contact element is reduced to a lower target temperature, a subsequent holding phase in which the contact element is substantially held at the target temperature, and a final heating phase, in which the contact element is brought to an upper target temperature. The use of contact elements treated using the method according to the invention leads to a substantial increase of the wear resistance compared to untreated contact elements.

A method and system for recovering a high yield of low carbon ferroalloy, e.g., low carbon ferrochrome, from chromite and low carbon ferrochrome produced by the method. A stoichiometric mixture of feed materials including scrap aluminum granules, lime, silica sand, and chromite ore are provided into a plasma arc furnace. The scrap aluminum granules are produced from used aluminum beverage containers. The feed materials are heated, whereupon the aluminum in the aluminum granules produces an exothermic reaction reducing the chromium oxide and iron oxide in the chromite to produce molten low carbon ferrochrome with molten slag floating thereon. The molten low carbon ferrochrome is extracted, solidified and granulated into granules of low carbon ferrochrome. The molten slag is extracted, solidified and granulated into granules of slag.

A quenching apparatus and a quenching method for a metal sheet with which it is possible to inhibit shape defects from occurring in the metal sheet when quenching is performed and a method for manufacturing a steel sheet. The quenching apparatus is placed on an exit side of a soaking zone in a continuous annealing furnace, and the apparatus includes a cooling fluid-spray device having plural spray nozzles for spraying mist onto both surfaces of a continuously transported metal sheet, and at least one pair of restraining rolls for restraining the metal sheet on both surfaces thereof in a region from a cooling start point to a cooling finish point in the cooling fluid-spray device.

The present invention relates to a method of hardening slides of a perforating press comprising providing a steel beam; hardening of the steel beam in a vacuum furnace; tempering the steel beam twice; first straightening of the steel beam at a temperature of 20? C.?10? C.; milling of an at least partially continuous sawtooth profile, along a longitudinal direction of the steel beam, on a first side of the steel beam; wherein, after milling the at least partially continuous sawtooth profile on the first side of the steel beam, a second side of the steel beam, lying opposite the first side, is hardened by means of induction currents, after which the steel beam is again tempered twice and after which the steel beam is straightened a second time at a temperature of 20? C.?10? C. The invention also relates to a slide for a perforating press hardened according to the method.

To provide a steel and a manufacturing method thereof that can contribute to achieving both high strength and hydrogen embrittlement resistance. The steel has a chemical composition represented by: C: 0.15% to 0.35%; Si: 0.8% to 2.5%; Mn: 0.8% to 2.5%; Al: 0.03% to 2.0%; N: 0.002% to 0.010%; P: 0.01% or less; S: 0.01% or less; O: 0.01% or less; B: 0.0001% to 0.005%; Nb: 0.0% to 0.05%; Ti: 0.0% to 0.2%; V 0.0% to 0.05%; Mo: 0.0% to 1.0%; Cr: 0.0% to 1.0%; Ni: 0.01% to 1.0%; Cu: 0.05% to 1.0%; at least one of Ca, Mg and REM: 0.0005% to 0.01%; and the balance: Fe and impurities, and has a martensite phase or/and a bainite phase in which ?-carbide is dispersedly precipitated.