A method of case hardening a titanium part, including placing the titanium part within a chamber; evacuating or purging the chamber; heating the titanium part placed within the chamber; introducing a gas containing cyanogen into the chamber; and exposing the titanium part placed within the chamber to the introduced gas containing cyanogen.

in a heat treatment method for a tubular shaft for a drive shaft having a ball spline structure for a plunging and an undercut region with a reduced diameter, a carburizing-austempering is performed such that a deep portion hardness of the undercut region is a value between HRC 35 to HRC 50.

in a heat treatment method for a tubular shaft for a drive shaft having a ball spline structure for a plunging and an undercut region with a reduced diameter, a carburizing-austempering is performed such that a deep portion hardness of the undercut region is a value between HRC 35 to HRC 50.

Provided are a steel that is for a die and that enables production of a die being for hot working and having both high hardness and high thermal conductivity; a die for hot working; and a manufacturing method for the same. The steel for a hot working die has a compositional makeup containing, in mass %, 0.45-0.65% of C, 0.1-0.6% of Si, 0.1-2.5% of Mn, 1.0-6.0% of Cr, 1.2-3.5% of (Mo+½W) where Mo and W are contained independently or in combination, 0.1-0.5% of V, 0.15-0.6% of Ni, 0.1-0.6% of Cu, and 0.1-0.6% of Al, the balance being Fe and inevitable impurities. Further, this die for hot working has said compositional makeup, and this manufacturing method is for manufacturing said die for hot working.

The disclosure provides a metal surface layer treating method, a metal assembly and an electronic device. The metal surface layer treating method includes: putting metal into a vacuum chamber, and vacuumizing the vacuum chamber to a first vacuum degree; adding a mixed gas of acetylene, nitrogen and hydrogen into the vacuum chamber; and heating the vacuum chamber to a temperature above an ambient temperature. In response to the temperature in the vacuum chamber reaching a first temperature value above the ambient temperature and a gas pressure of the vacuum chamber reaching a first pressure value, performing glow discharge so that a carbon-nitrogen gradient hardening layer is formed on a surface layer of the metal. The method includes removing part of a carbon layer of the surface layer of the carbon-nitrogen gradient hardening layer.

A method of treating a sintered mining insert including cemented carbide includes the step of subjecting the mining insert to a surface hardening process. The surface hardening process is executed at an elevated temperature of or above 100° C. A mining insert is also provided, wherein the HV1 Vickers hardness measurement increase (HV1%) from the surface region, measured as an average of HV1 measurements taken at 100 μm, 200 μm and 300 μm below the surface, compared to the HV1 Vickers hardness measured in the bulk (HV1bulk), is at least 8.05-0.00350×HV1bulk.

A method of treating a sintered mining insert including cemented carbide includes the step of subjecting the mining insert to a surface hardening process. The surface hardening process is executed at an elevated temperature of or above 100° C. A mining insert is also provided, wherein the HV1 Vickers hardness measurement increase (HV1%) from the surface region, measured as an average of HV1 measurements taken at 100 μm, 200 μm and 300 μm below the surface, compared to the HV1 Vickers hardness measured in the bulk (HV1bulk), is at least 8.05-0.00350×HV1bulk.

An example component of a machine includes a core layer and an outer layer encasing the core layer. The outer layer has a greater carbon concentration and hardness than the core layer. The outer layer may also be compressively stressed, while the core layer may have tensile stress. The stress and/or hardness profile of the component may enhance its resistance to cracking, particularly in applications where the component is impacted by other object and/or operates at elevated temperatures. The component, such as parts of a fuel injector, may be formed by rough forming the component, carburizing the component, quenching the component, subzero processing the component, and then performing a tempering process. The components may have relatively sharp transition from the high carbon outer layer to the lower carbon core layer. Additionally, the components have a relatively high tempering resistance when used in relatively high temperature environments.

An example component of a machine includes a core layer and an outer layer encasing the core layer. The outer layer has a greater carbon concentration and hardness than the core layer. The outer layer may also be compressively stressed, while the core layer may have tensile stress. The stress and/or hardness profile of the component may enhance its resistance to cracking, particularly in applications where the component is impacted by other object and/or operates at elevated temperatures. The component, such as parts of a fuel injector, may be formed by rough forming the component, carburizing the component, quenching the component, subzero processing the component, and then performing a tempering process. The components may have relatively sharp transition from the high carbon outer layer to the lower carbon core layer. Additionally, the components have a relatively high tempering resistance when used in relatively high temperature environments.

The present invention is to provide a steel plate with physical properties superior to existing steel plates used in fields such as industrial machinery, especially excellent low-temperature impact toughness along with high strength and high hardness, and a method for manufacturing same.