In order to provide a high-hardness, high-toughness steel, Si, Al, Cr, Mo, V, W, Ni, and Co are more appropriately added so that the steel can have an HRC hardness of 50 or higher and a Charpy impact value of 5 kgf m/cm 2 or more by tempering at a high temperature of 600° C or higher The steel is a martensite steel containing at least C: 015 to 12% by weight and Si: 005 to 18% by weight, wherein Si is partially replaced by 015 to 16% by weight of Al The steel further contains Ni: 03 to 25% by weight; Cr: 01 to 35% by weight; Mo: 01 to 17% by weight, wherein the amount of Mo is not more than the upper limit determined by the relation formula: Mo(% by weight)=17−05×(Si(% by weight)+Al(% by weight)); one or both of V: 005 to 040% by weight and W: 01 to 10% by weight; at least one alloying element of Mn, Co, Cu, Ti, B, and Nb; inevitable impurities including P, S, N, and O; and the balance consisting essentially of Fe

High-hardness, high-toughness steels and crawler components, earth wear resistant components, fastening bolts, high-toughness gears, high-toughness, high contact pressure resistance gears, and wear resistant steel plates using the same

A mechanical part consisting of an outer member having a race surface on the inner side therof, an inner member having a race surface on the outer side thereof, and rolling elements inserted between the race surfaces of these outer and inner members. Mechanical parts of this kind include a hub bearing and a constant-speed universal joint for automobiles, which are required to reduce the dimensions and weight thereof. The outer member having a complicated shape is formed out of medium carbon steel which can be processed easily, and its race surface is subjected to induction hardening, so that the resultant hardened surface layer can ensure a sufficient abrasion resistance. However, how to prolong the lifetime of the rolling elements, such as balls, used under a high surface pressure but increasingly reducted in weight, is posing a problem. The mechanical part according to the present invention has an induction hardened layer as a race surface layer of its outer member, and consists of medium carbon steel containing 0.50-0.70 % by weight of carbon and 0.5-1.0 % by weight of silicon and/or aluminum. The rolling elements rolling or slidingly moving on the mentioned race surfaces are formed out of hardened and tempered high carbon chromium bearing steel, and have carbonitrided surface layer, and this enables the lifetime of the rolling elements under a high surface pressure to be improved.

Mechanical part having rolling elements

There is provided an inexpensive rolling element used under high interface pressure such as induction hardened gears, the rolling element being improved in the seizure resistance of its tooth flanks and having a temper hardness of HRC 50 or more at 300° C. To this end, the rolling element is made from a steel material containing at least 0.45 to 1.5 wt % C and one or more alloy elements selected from 0.1 to 0.5 wt % V and 0.3 to 1.5 wt % Cr, and has a rolling contact surface layer having a structure tempered at low temperature in which 2 to 18% by volume cementite disperses in a martensite parent phase formed by induction heating and cooling and containing 0.25 to 0.8 wt % carbon solid-dissolving therein.

Rolling element and method of producing the same

A water-resistant and long-life rolling bearing used in an environment involving water's seeping in the lubricant thereof, wherein at least one of the inner race, the outer race, and the rolling member is formed of alloy steel containing 0.05 to 0.60% by weight of Cu, 0.10 to 1.10% by weight of C, and 0 to 0.2% by weight of Nb or V. The alloy steel has functions of reducing hydrogen evolution on the surface thereof and of forming a film hardly permeable to hydrogen thereby to retard occurrence of flaking due to hydrogen-induced brittleness.

Water resistant long-life rolling bearing

The present invention provides a bearing component formed from a steel composition comprising: (a) from 0.5 - 1.2 wt. % carbon, (b) from 0.15 - 2 wt. % silicon, (c) from 0.25 - 2 wt. % manganese, (d) from 0.85 - 3 wt. % chromium, (e) optionally one or more of the following elements from 0 - 5 wt. % cobalt, from 0 - 2 wt. % aluminium, from 0 - 0.6 wt. % molybdenum, from 0 - 0.5 wt. % nickel, from 0 - 0.2 wt. % vanadium, from 0 - 0.1 wt. % sulphur, from 0 - 0.1 wt. % phosphorous, and (f) the balance iron, together with unavoidable impurities.

A bearing component

A bearing race member composed of steel containing 0.60 to 0.85% carbon by weight, 0.5 to 1.0% by weight in a single content or total contents of Si and Al, and 13 ppm or less oxygen, wherein said bearing race member is quenched and subsequently tempered to contain 15% or less retained austenite therein. Even though basically made of structural carbon steel, the bearing race member has a long life equal to that of high-carbon chromium bearing steel and is superior in dimensional stability and crack fatigue strength.

Hirotsugu Hamaoka

Papers

Bearing race member and method of fabrication

Steel bearing race member

Bague pour roulement