A method of making a forged, martensitic, stainless steel alloy is provided. The alloy is a forged preform of martensitic, pitting corrosion resistant stainless steel alloy comprising, by weight: 12.0 to 16.0 percent chromium; greater than 16.0 to 20.0 percent cobalt, 6.0 to 8.0 percent molybdenum, 1.0 to 3.0 percent nickel, 0.02 to 0.04 percent carbon; and the balance iron and incidental impurities. The alloy has a microstructure that comprises a retained austenite phase less than or equal to 2 percent by volume of the microstructure. The method heats the preform to a solutionizing temperature to form a solutionized microstructure. The preform is cooled with a liquid to room temperature. The preform is immersed in a cryo-liquid to transform the retained austenite phase in the microstructure to martensite. The preform is heated to a temperature of less than 600° F. for a time sufficient to form a tempered forged preform.

A planetary gear system includes a planetary gear carrier having three or more posts extending from the planetary gear carrier, each post having a hardened exterior surface, and a planet pinion gear in contact with the hardened exterior surface of each post.

A planetary gear system includes a planetary gear carrier having three or more posts extending from the planetary gear carrier, each post having a hardened exterior surface, and a planet pinion gear in contact with the hardened exterior surface of each post.

A case hardening steel suitable as raw material for producing a mechanical structural part having high rotating bending fatigue strength and pitting fatigue strength at relatively low cost and a method of producing the case hardening steel are provided. A case hardening steel comprises a chemical composition containing, in mass %, C, Si, Mn, P, S, Cr, Mo, Al, N, and O in a predetermined relationship, with a balance being Fe and inevitable impurities, wherein √I≤80 (where I denotes an area (μm.sup.2) of an oxide-based inclusion located in a fish eye central portion at a fracture surface after subjecting the case hardening steel to carburizing-quenching and tempering and then performing a rotating bending fatigue test).

A case hardening steel suitable as raw material for producing a mechanical structural part having high rotating bending fatigue strength and pitting fatigue strength at relatively low cost and a method of producing the case hardening steel are provided. A case hardening steel comprises a chemical composition containing, in mass %, C, Si, Mn, P, S, Cr, Mo, Al, N, and O in a predetermined relationship, with a balance being Fe and inevitable impurities, wherein √I≤80 (where I denotes an area (μm.sup.2) of an oxide-based inclusion located in a fish eye central portion at a fracture surface after subjecting the case hardening steel to carburizing-quenching and tempering and then performing a rotating bending fatigue test).

A rack bar includes: a rack tooth row including a plurality of rack teeth meshing with pinion teeth; a hardened layer provided continuously over an entire circumference of the rack tooth row; and a center portion provided inside the hardened layer and having lower hardness than the hardened layer. When the rack bar is viewed in an axial direction of the rack bar, a depth of the hardened layer from the following positions i), ii), and iii) increases in this order: i) a bottom land of the rack teeth; ii) a side of the rack bar relative to the bottom land; and iii) a back of the rack bar relative to the bottom land.

Methods for treating steel, along with the resulting treated steel, are provided. The method may comprise: nitriding a carburized Ferrium steel component such that the Ferrium steel component has a surface portion with a nitrogen content that is greater than 0% to about 5% by weight. Nitriding the Ferrium steel component may increase the surface hardness of the Ferrium steel. The surface portion may have a nitrogen content of about 0.05% to about 0.5% by weight.

Methods for treating steel, along with the resulting treated steel, are provided. The method may comprise: nitriding a carburized Ferrium steel component such that the Ferrium steel component has a surface portion with a nitrogen content that is greater than 0% to about 5% by weight. Nitriding the Ferrium steel component may increase the surface hardness of the Ferrium steel. The surface portion may have a nitrogen content of about 0.05% to about 0.5% by weight.

Provided are a dual-frequency power-supply apparatus, a high-frequency heating apparatus, and a high-frequency quenching apparatus having a high durability.

A dual-frequency power-supply apparatus 1 includes a power supply 10 that alternately outputs a low-frequency current and a high-frequency current. The power supply 10 has an inverter 30 that converts a direct current into the low-frequency current and the high-frequency current and a controller 40 that controls the inverter 30. The controller 40 repeats, in this order, a first output period T11 in which the low-frequency current is output, a first intermission T12 in which output is stopped, a second output period T13 in which the high-frequency current is output, and a second intermission T14 in which output is stopped. The controller 40 sets the length of the first intermission T12 longer than a time Ta until the polarity of the output voltage of the power supply 10 is reversed fourthly after transition from the first output period T11 to the first intermission T12.

The present invention belongs to the field of mechanical engineering and materials, more specifically in the metallurgy segments, for application in the sugar industry. The invention relates to the hot forging process of mill shafts and heat-treated auxiliary equipment in CrNiMo and low carbon alloy. The shafts and auxiliary equipment manufactured according to this invention have a long service life, thus reducing downtime for maintenance and increasing reliability, since it eliminates the problems associated with cracks and instantaneous fractures. As a consequence, there is a reduction in the risks of accidents and production losses associated with stoppages.