The present invention provides a steel wire rod with stable workability. The steel wire rod has steel components containing, by mass %, C: 0.20 to 0.60%, Si: 0.15 to 0.30%, Mn: 0.25 to 0.60%, P: 0.020%, S: 0.010%, and a balance of Fe and unavoidable impurities, and an internal microstructure including cementite, in which by number ratio, 80% or more of the cementite in a cross-section vertical to a longitudinal direction of the wire rod has a short axis of 0.1 m or less and a ratio of a long axis to the short axis, defined as an aspect ratio, of 2.0 or less.

A steel wire for non-heat treated machine parts, the steel wire contains, based on % by mass: C: from 0.20 to 0.40%, Si: from 0.05 to 0.50%, Mn: from 0.50 to 2.00%, Al: from 0.005 to 0.050%, and the balance being Fe and impurities, in which the microstructure contains bainite of (35[C %]+50)% or more, and when the diameter is defined as D, the average aspect ratio of a bainite grain at a depth of 50 m in the L cross section is defined as AR, and the average grain size of a bainite grain at a depth of 50 M in the C cross section is defined as GD, AR is 1.4 or more, (AR)/(the average aspect ratio of a bainite grain at a depth of 0.25D in the L cross section) is 1.1 or more, GD is (15/AR) m or less, and (GD)/(the average grain size of a bainite grain at a depth of 0.25D in the C cross section) is less than 1.0.

Methods for modifying a physical characteristic of finished endodontic instruments made from one or more superelastic alloys is described which include heat treating one or more finished endodontic instruments in a salt bath for a specific time (e.g., from about four hours to about six hours), at a specified temperature (e.g., from about 475 C. to about 550 C.), and preferably at a specified pH range.

Methods for modifying a physical characteristic of finished endodontic instruments made from one or more superelastic alloys is described which include heat treating one or more finished endodontic instruments in a salt bath for a specific time (e.g., from about four hours to about six hours), at a specified temperature (e.g., from about 475 C. to about 550 C.), and preferably at a specified pH range.

A sliding member (1) includes an iron and steel-based sintered compact containing chromium, molybdenum, and carbon and having a content of chromium, of 5 mass % or less. The sliding member (1) includes: a compound layer (11) which has a sliding surface (1a) and is formed mainly of an iron and steel nitride; and a diffusion layer (12) which is adjacent to the compound layer (11) and has an iron and steel structure into which nitrogen and carbon diffuse. The concentrations of carbon and nitrogen in the diffusion layer (12) are gradually reduced with increasing depth from the sliding surface (1a).

The present invention provides a steel wire rod with stable workability. The steel wire rod has steel components containing, by mass %, C: 0.20 to 0.60%, Si: 0.15 to 0.30%, Mn: 0.25 to 0.60%, P: 0.020%, S: 0.010%, and a balance of Fe and unavoidable impurities, and an internal microstructure including cementite, in which by number ratio, 80% or more of the cementite in a cross-section vertical to a longitudinal direction of the wire rod has a short axis of 0.1 m or less and a ratio of a long axis to the short axis, defined as an aspect ratio, of 2.0 or less.

This invention relates to a surface heat treatment method in a salt bath at low temperature, suitable for partially hardening the surface of a workpiece through heat treatment, including plating the surface of a workpiece with a first metal layer; partially peeling the first metal layer; heat treating the workpiece at a temperature of 400 to 500 C. for a predetermined period of time; and totally peeling the first metal layer. Thereby, low-temperature heat treatment is effective at heat treating the workpiece while minimizing deterioration of corrosion resistance.

This invention relates to a surface heat treatment method in a salt bath at low temperature, suitable for partially hardening the surface of a workpiece through heat treatment, including plating the surface of a workpiece with a first metal layer; partially peeling the first metal layer; heat treating the workpiece at a temperature of 400 to 500 C. for a predetermined period of time; and totally peeling the first metal layer. Thereby, low-temperature heat treatment is effective at heat treating the workpiece while minimizing deterioration of corrosion resistance.