Komatsu Corporation

Chikara Nakao

Takemori Takayama

Noriko Morioka

Masanari Furumoto

Takashi Kuse

Naoji Hamasaka

A ferrous seal sliding part excellent in heat crack resistance, seizure resistance and abrasion resistance is provided. The ferrous seal sliding part has a seal sliding surface, wherein the seal sliding surface has a quench hardened layer having a structure in which a martensite parent phase forms a solid solution with carbon of 0.15 to 0.6 wt % and contains cementite dispersed therein in a content of 3 to 50% by volume.

Ferrous seal sliding parts and producing method thereof

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&#xb0; 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.

Case hardened gear and method of producing the same

Rolling element and method of producing the same

A primary purpose is to provide an inexpensive high-toughness wear-resistant steel having satisfactory toughness where its hardness is HRC 55 or more. This steel contains at least 0.21 to 0.80 wt % C; 0.3 to 2.0 wt % Al; and 0.5 to 4.0 wt % Ni as essential components and further contains alloy elements such as Si, Mn, Cr, Mo, W, V, Ti, Cu and B; unavoidable impurities such as P, S, N and O; and the remainder which substantially consists of a tempered martensitic steel of Fe.

High-toughness wear-resistant steel

For easily producing a toothed material for high-strength gears etc. with a plastic working technique, deformation resistance occurring in plastic working is reduced and stable high precision plastic working is enabled at lower temperatures. One or more types of heat treatment selected from carburization, carbonitriding and nitriding and a hardening process are applied to an alloy steel material containing: iron as a main component; at least 1.0 to 4.5 wt % Si; 0.35 wt % or less C; and balance Fe and unavoidable impurities, whereby a rolling element is obtained which has a surface layer mainly composed of martensite containing no &agr;-Fe phase and of residual austenite and an inner structure cooled from an (&agr;&plus;&ggr;)-Fe two phase region.

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Hirakata, Japan

Chikara Nakao