A cast lip for an excavating bucket composed of a ferrous alloy having at least seven percent chromium by weight, 3%-6% nickel by weight, and 0.12% carbon by weight, and a primarily martensitic structure.

Austempered steel for components requiring high strength and high ductility and/or fracture toughness, which has a silicon content of 3.1 weight-% to 4.4 weight-% and a carbon content of 0.4 weight-% to 0.6 weight-%. The microstructure of the austempered steel is ausferritic or superbainitic.

An improved crushing tool for the processing of aggregates, and a heat treatment method for metals used in the fabrication of such tools, is provided. The crushing tool may comprise an attachment portion having a relatively low material hardness and a crushing portion having, in comparison to the attachment portion, a relatively high material hardness. For example, the hardness of the attachment portion may be in the range of 20-35 HRC, and that of the crushing portion may be in the range of 50-60 HRC. Use of tool-grade steel, such as AISI S7 steel, may thereby result in a tool offering a compromise between the hardness (wear-resistance) of the crushing portion and the toughness of the attachment portion. A heat treatment process for the tool-grade steel may involve distinct heating, quenching, and tempering cycles in order to achievable desirable material properties.

A matrix type hot work tool steel, in use, has an improved abrasive wear resistance in demanding applications. The steel is suited for applications in hot forging, die casting or hot extrusion. It is also suitable for press hardening, in particular for press hardening of Advance High Strength Steel (AHSS) and has a high hot wear resistance. The hot work tool steel has a composition including, in weight % (wt. %): C 0.65-0.85; Si 0.03-0.8; Mn 0.1-1.8; Cr 4.5-6.6; Mo 1.8-3.5; V 1.3-2.3; Al0.1; N0.12; Ni1; W0.5; Co2; Cu1; Nb0.1; Ti0.05; Zr0.05; Ta0.05; B0.01; Ca0.01; Mg0.01; REM0.2; and balance Fe and impurities.

The present invention is a processing method for a metal component by using a processing furnace. The method includes the steps of: introducing an activation atmospheric gas into the processing furnace; heating the activation atmospheric gas in the processing furnace to a first temperature; introducing a nitriding atmospheric gas or a nitrocarburizing atmospheric gas into the processing furnace; and heating the nitriding atmospheric gas or the nitrocarburizing atmospheric gas in the processing furnace to a second temperature. The activation atmospheric gas is introduced into the processing furnace through a pipe for introducing the activation atmospheric gas. A liquid organic solvent is introduced intermittently a plurality of times into the pipe for introducing the activation atmospheric gas which is under a state wherein the activation atmosphere gas continues to be introduced.

Provided is a method for producing a galvannealed steel sheet. When the steel sheet passing through the soaking zone is a type of steel containing 0.2 mass % or more of Si, both dry gas and humidified gas are supplied to the soaking zone, where the humidified gas is supplied only from the humidified gas supply port positioned in a latter part of the soaking zone among a plurality of humidified gas supply ports, where the latter part of the soaking zone is determined considering a sheet passing speed V and a target temperature T on the exit side of the soaking zone.

A far-infrared radiation multi-stage type heating furnace for steel sheets for hot stamping, the furnace including far-infrared radiation heaters having flexibility that are prevented from deflecting even during heating at temperatures ranging from the Ac.sub.3 transformation temperature to 950 C. The furnace includes: multiple-staged heating units that accommodate steel sheets, each heating unit formed by thermal insulation materials disposed around the periphery; and far-infrared radiation heaters positioned above and below the heating units. A far-infrared radiation heater is received by first metal strips. The first metal strips are disposed so that their strong axis direction approximately corresponds to the direction of gravity and supported by support pieces so as to be expandable and contractible in a longitudinal direction by thermal expansion or thermal contraction. The support pieces are disposed outside the thermal insulation materials in the heating units and a ceiling unit.

A far-infrared radiation multi-stage type heating furnace for steel sheets for hot stamping, the furnace including far-infrared radiation heaters having flexibility that are prevented from deflecting even during heating at temperatures ranging from the Ac.sub.3 transformation temperature to 950 C. The furnace includes: multiple-staged heating units that accommodate steel sheets, each heating unit formed by thermal insulation materials disposed around the periphery; and far-infrared radiation heaters positioned above and below the heating units. A far-infrared radiation heater is received by first metal strips. The first metal strips are disposed so that their strong axis direction approximately corresponds to the direction of gravity and supported by support pieces so as to be expandable and contractible in a longitudinal direction by thermal expansion or thermal contraction. The support pieces are disposed outside the thermal insulation materials in the heating units and a ceiling unit.

A heat treatment apparatus 1 includes a coolant passage defining body 42 to define a coolant passage 48 to supply a coolant to a workpiece 100. The coolant passage defining body 42 includes an upper member 50 and a lower member 40 as a plurality of coolant passage defining members, and is configured so that, by displacing these members 49 and 50 so as to approach each other along an up-down direction Z1 crossing a conveyance direction, the coolant passage 48 is defined in a state housing the workpiece 100. In addition, the coolant passage defining body is configured so that, by displacing the members 49 and 50 described above so as to separate from each other along the up-down direction Z1, the workpiece 100 is allowed to be let into and out of the coolant passage 48 along the conveyance direction A1.

Steel has a chemical composition that contains 0.050% to 0.40% of C, 0.50% to 3.0% of Si, 3.0% to 8.0% of Mn, and 0.001% to 3.0% of sol. Al, by mass %, and has a metallographic structure that contains 10% to 40% of austenite in terms of % by volume. The average concentration of C in austenite is 0.30% by 0.60%, by mass %, structure uniformity, which is represented by a value obtained by subtracting the minimum value from the maximum value of Vickers hardness that is measured, in the metallographic structure is 30 Hv or less, and the tensile strength is 900 MPa to 1800 MPa.