A method for producing a surface-hardened material, comprising: an immersion step of immersing an iron steel material having nitrogen attached in the form of a solid solution on the surface thereof in a melt containing a chloride at a temperature ranging from 650 C. to 900 C.; and a cooling step of cooling the immersed iron steel material to a temperature equal to or lower than a martensitic transformation start temperature at a cooling rate equal to or higher than a lower critical cooling rare at which martensitic transformation starts.

A method of treating a surface of a gear for a strain wave reduction gear mechanism. The method includes: taking a gear for a strain wave reduction gear mechanism as a workpiece, the gear is formed from a machine structural steel containing at least 0.2% carbon and being subjected to heat treatment after having been machined; performing a first process in which carbide particles are ejected against a surface of the workpiece so as to remove machining marks on the surface of the workpiece and so as to cause elemental carbon in the carbide particles to diffuse and permeate into the surface of the gear; and after the first process, performing a second process in which spherical particles are ejected against a surface of the workpiece for increasing an internal compressive residual stress of the gear surface by a magnitude of at least 50 MPa.

A method of treating a surface of a gear for a strain wave reduction gear mechanism. The method includes: taking a gear for a strain wave reduction gear mechanism as a workpiece, the gear is formed from a machine structural steel containing at least 0.2% carbon and being subjected to heat treatment after having been machined; performing a first process in which carbide particles are ejected against a surface of the workpiece so as to remove machining marks on the surface of the workpiece and so as to cause elemental carbon in the carbide particles to diffuse and permeate into the surface of the gear; and after the first process, performing a second process in which spherical particles are ejected against a surface of the workpiece for increasing an internal compressive residual stress of the gear surface by a magnitude of at least 50 MPa.

The present disclosure relates to a method for producing a coating film having high heat resistance, high hardness and wear resistance, a coating film having high heat-resistance, high hardness and wear resistance produced using the method, and a cutting tool including the same. The method includes forming a metal nitride layer on a metal base; forming a carbon layer on the metal nitride layer; and irradiating a laser into the carbon layer to add carbons into a portion of the metal nitride layer, thereby to form a carburized layer.

The present disclosure relates to a method for producing a coating film having high heat resistance, high hardness and wear resistance, a coating film having high heat-resistance, high hardness and wear resistance produced using the method, and a cutting tool including the same. The method includes forming a metal nitride layer on a metal base; forming a carbon layer on the metal nitride layer; and irradiating a laser into the carbon layer to add carbons into a portion of the metal nitride layer, thereby to form a carburized layer.

The present disclosure provides a thermal spray alloy system that is more resistant to wear and/or corrosion than conventional alloy compositions. The disclosed alloys minimize or eliminate micro-cracks within the formed coating on the tool. The alloy comprises carbon, boron, and a fluxing agent selected from the group of aluminum, magnesium, or lithium. The alloy may also comprise titanium, silicon, manganese, molybdenum, nickel, and chromium, as well as other elements. The object to be coated may be any downhole component used in the oil and gas industry, or may be applied to any object or tool that needs an increased wear and/or corrosive protection layer including in diverse fields such as marine, chemical processing, and refining. A thermal spray coating with the disclosed alloy composition provides increased strength and resistance to spalling, breaking, cracking, deforming, and crack formation, as well as metallurgical bonding between the coating and the substrate.

A method of hardening a surface of a ferro-alloy object, the method comprising at least partially gasifying a carbon-containing polymer to form a hardening material source; and exposing the object to the hardening material source, such that the hardening material source and the surface of the object react, thereby hardening the surface of the object.

A method of hardening a surface of a ferro-alloy object, the method comprising at least partially gasifying a carbon-containing polymer to form a hardening material source; and exposing the object to the hardening material source, such that the hardening material source and the surface of the object react, thereby hardening the surface of the object.

A method for treating sheet metal is disclosed in which a material containing at least one alloying element is applied onto a first area of at least one surface of the metal sheet. A second area of the surface is kept free of the material. The metal sheet is subsequently heat treated in order to diffuse the alloying element into the first area of the metal sheet. The temperature of the first area is lower than the melting temperature of the metal sheet during the diffusion.

A method for treating sheet metal is disclosed in which a material containing at least one alloying element is applied onto a first area of at least one surface of the metal sheet. A second area of the surface is kept free of the material. The metal sheet is subsequently heat treated in order to diffuse the alloying element into the first area of the metal sheet. The temperature of the first area is lower than the melting temperature of the metal sheet during the diffusion.