A sprocket wheel, which is a machine component configured to slide relative to a bushing while being in contact with the bushing in an outer peripheral surface, includes a base made of a first metal, and an overlay that covers the base so as to constitute the outer peripheral surface. The surface of the overlay constituting the outer peripheral surface has been smoothed. Such a smoothed surface of the overlay makes the sprocket wheel less damaging to the bushing.

A sprocket wheel, which is a machine component configured to slide relative to a bushing while being in contact with the bushing in an outer peripheral surface, includes a base made of a first metal, and an overlay that covers the base so as to constitute the outer peripheral surface. The surface of the overlay constituting the outer peripheral surface has been smoothed. Such a smoothed surface of the overlay makes the sprocket wheel less damaging to the bushing.

A composite casting special-shaped roll is compounded of two parts: an inner layer and an outer layer. The shape of body of the roll is curved surface, and a center hole is arranged for mount the shaft in that central axis of roll. The casting mold is designed into two parts, namely inner cast mold and outer cast mold through the curved surface design and mold design of the roll body. The composite casting special-shaped roll with the wear-proof working layer of the roll body that is resistant to impact, rapid cooling and heating resistance and the high-strength and high-toughness core is prepared by separate casting. It meets the requirements of the service conditions of rolls used by the steel pipe and cold forming sectional steel rolling mill and other equipment, improves the service life of the roll, saves the alloy material and reduces the manufacturing cost.

A composite casting special-shaped roll is compounded of two parts: an inner layer and an outer layer. The shape of body of the roll is curved surface, and a center hole is arranged for mount the shaft in that central axis of roll. The casting mold is designed into two parts, namely inner cast mold and outer cast mold through the curved surface design and mold design of the roll body. The composite casting special-shaped roll with the wear-proof working layer of the roll body that is resistant to impact, rapid cooling and heating resistance and the high-strength and high-toughness core is prepared by separate casting. It meets the requirements of the service conditions of rolls used by the steel pipe and cold forming sectional steel rolling mill and other equipment, improves the service life of the roll, saves the alloy material and reduces the manufacturing cost.

An outer layer of a rolling roll having a chemical composition comprising by mass 1.3-2.8% of C, 0.3-1.8% of Si, 0.3-2.5% of Mn, 0-6.5% of Ni, 1-10% of Cr, 0.9-6% of Mo, 0-8% of W, 0.5-6% of V, 0-3% of Nb, and 0% or more and less than 0.01% of B, the balance being Fe and inevitable impurities, and meeting the formulae (1): 1000117752C+14Si11Mn+6.8Cr+1W+0.65Mo+12V+15Nb1115, and (2): 5Cr+Mo+0.5W+V+1.2Nb15, wherein C, Si, Mn, Cr, W, Mo, V and Nb represent % by mass of these elements, and a structure containing eutectic carbide without graphite.

The invention relates to a method for producing a rolling bearing ring featuring an improved robustness against the formation of white etching cracks (WEC), wherein the rolling bearing component, which is made of a hypo-eutectoid heat-treated steel containing C in an amount of 0.4-0.55% and Cr in an amount of 0.5-2.0% in order to form a hardened boundary layer, is inductively heated, then quenched and subsequently tempered.

A martensitic alloy component includes by weight, 0.25% to 0.31% carbon (C), 2.1% to 3.0% manganese (Mn), 0.22% to 0.28% silicon (Si), 2.0% to 2.2% chromium (Cr), 0.45% to 0.55% molybdenum (Mo), 0.08% to 0.12% vanadium (V), and the balance is iron (Fe) and incidental impurities. The manganese-chromium martensitic alloy component has a hardenability corresponding to an ideal diameter of about 15 inches to about 30 inches or more.

A martensitic alloy component includes by weight, 0.25% to 0.31% carbon (C), 2.1% to 3.0% manganese (Mn), 0.22% to 0.28% silicon (Si), 2.0% to 2.2% chromium (Cr), 0.45% to 0.55% molybdenum (Mo), 0.08% to 0.12% vanadium (V), and the balance is iron (Fe) and incidental impurities. The manganese-chromium martensitic alloy component has a hardenability corresponding to an ideal diameter of about 15 inches to about 30 inches or more.

Provided is a tripod type constant velocity universal joint (1), including: an outer joint member (2) having track grooves (6) formed at trisected positions in a circumferential direction to extend in an axial direction; a tripod member (3) including leg shafts (9) radially projecting from trisected positions in the circumferential direction; and rollers (4) fitted in a freely rotatable manner about the leg shafts (9), respectively, and received in the track grooves (6), respectively, in which a radially outer surface (4a) of each of the rollers (4) is formed of a surface unsubjected to grinding or cutting work after heat treatment.

Provided is a tripod type constant velocity universal joint (1), including: an outer joint member (2) having track grooves (6) formed at trisected positions in a circumferential direction to extend in an axial direction; a tripod member (3) including leg shafts (9) radially projecting from trisected positions in the circumferential direction; and rollers (4) fitted in a freely rotatable manner about the leg shafts (9), respectively, and received in the track grooves (6), respectively, in which a radially outer surface (4a) of each of the rollers (4) is formed of a surface unsubjected to grinding or cutting work after heat treatment.