A track pin for a track chain assembly includes a body made from a steel alloy. The steel alloy has a composition comprising iron, a nitride-forming element, a carbide-forming element, and silicon. The composition of the steel alloy comprises at least 0.5 percent by weight of silicon. The body includes a compound layer on an exterior surface thereof. The compound layer includes at least one of Fe.sub.2-3(C,N) microstructures and Fe.sub.4N microstructures formed therein by ferritic nitro-carburizing.

A track link which is a tracked undercarriage component is made of a steel having a specific component composition, and includes a high hardness portion having a hardness of HRC 57 or more and HRC 60 or less, and a low hardness portion. The high hardness portion includes a first matrix including a martensite phase and a residual austenite phase, and first nonmetallic particles dispersed in the first matrix and including at least one species selected from the group consisting of MnS, TiCN, and NbCN, and it does not include a M.sub.23C.sub.6 carbide. The low hardness portion includes a second matrix including a martensite phase, and second nonmetallic particles dispersed in the second matrix and including at least one species selected from the group consisting of MnS, TiCN, and NbCN, and it does not include a M.sub.23C.sub.6 carbide.

The present application relates to a steel for grade R6 offshore mooring chain for use in anchoring and mooring floating bodies with cathodic protection: the chemical composition are C 0.18˜0.24%, N 0.006˜0.024, P 0.005˜0.025, S≤0.005, Si 0.15˜0.35, Mn 0.20˜0.40, Cr 1.40˜2.60, Ni 0.80˜3.20, Mo 0.35˜0.75, Cu≤0.50, Al≤0.02, Ti≤0.005, V 0.04˜0.12, Nb 0.02˜0.05, Ca 0.0005˜0.004, O≤0.0015, H≤0.00015, the balance is Fe: the total content of alloy ΣM=(Si+Mn+Cr+Ni+Mo+Cu), 3.4<ΣM≤6.8; the total content of microalloy ΣMM=(Ti+Al+Nb+V), 0.065≤ΣMM≤0.194. The corrosion potential is adjusted to prevent hydrogen embrittlement caused by cathodic overprotection on the basic premise of maintaining the strength, toughness and low corrosion rate of the steel. Where V is only used for strengthening, and the content of N in VCN is increased, especially for the increase of the temperature for chain quenching to make M3C, M2C and VCN fully dissolved in solid solution and fully precipitated in tempering, which improves the precipitation strengthening effect.

Disclosed is a chain element (2), in particular for a power transmission chain of a chain drive, made of a carbon-containing material, especially steel, characterized by a core layer (5) that has a ferritic matrix structure including at least one hard phase that is distributed therein, and a hardened peripheral layer (6) that has a martensitic structure.

An example bushing has three portions along its radial direction including an inner portion most proximal to a central hole of the bushing, an outer portion most distal from the center hole, and a core portion between the inner portion and the outer portion. The core portion has a hardness that is less than the hardness of the inner portion or the outer portion of the bushing. The bushing may be formed using high carbon steel, which in some cases may be spheroidal cementite crystal structure. A rough bushing may be formed using the high carbon steel, followed by a direct hardening process, and an induction hardening process on the inner surface most proximal to the central hole of the bushing. The induction hardening on the inner surface may harden the outer portion while tempering the core portion of the bushing.

In one embodiment of the present disclosure, a drive chain system (22, 24) for a spiral conveyor belt (34) includes inner (52) and outer (62) drive chains driving the spiral conveyor belt, the inner and outer drive chains each including a plurality of links (70) defined by a plurality of first (72) and second (74) pitches connected by linking pins (84, 86) extending through holes (80, 82) in the pitches, wherein at least a portion of the linking pins of at least one of the inner and outer drive chains are hardened and/or dissimilar linking pins which are harder on an outer surface than other components in the inner and outer drive chains.

A roller chain having at least one pair of offset links wherein the offset link plates are made with a steel having a high chromium content and are through-hardened using an austempering heat treatment (such as a salt bath quench). The resulting offset link plates may have a hardness in range of 44-50 HRC on the Rockwell hardness scale and a bainite metallurgical microstructure. The offset link plates may also have a greater fatigue strength than at least one of the inner link plates and the outer link plates. The inner and outer link plates may be formed out of a plain carbon steel which is heated, quenched and tempered to produce a martensite microstructure.

In one embodiment of the present disclosure, a drive chain system (22, 24) for a spiral conveyor belt (34) includes inner (52) and outer (62) drive chains driving the spiral conveyor belt, the inner and outer drive chains each including a plurality of links (70) defined by a plurality of first (72) and second (74) pitches connected by linking pins (84, 86) extending through holes (80, 82) in the pitches, wherein at least a portion of the linking pins of at least one of the inner and outer drive chains are hardened and/or dissimilar linking pins which are harder on an outer surface than other components in the inner and outer drive chains.

A track link includes an elongate link body formed of a link body material that varies in hardness to form a first lower hardness zone, a second lower hardness zone, and a higher hardness zone. The higher hardness zone includes an upper rail surface of the elongate link body and extends substantially throughout the elongate link body outside of the first and second lower hardness zones, which surround the track pin bores. Related methodology for making a track link is also disclosed.

A roller chain includes pins, bushings, rollers, inner plates and outer plates. Two bushings are connected to one another in each case by way of at least two inner plates to form a chain link. Two consecutive chain links are articulately connected to one another in each case by way of each bushing being seated on a pin projecting beyond both ends of the bushing. At least one combination, which consist of two mutually frictionally engaged componentsthe pin and bushing on the one hand, the bushing and roller on the other hand,include one component consisting of austenitic stainless steel with an S-phase formed at least on the surface by way of nitriding at a temperature between about 400 C. and 500 C., and another component consisting of a stainless ferritic steel, which at least on the surface, is nitrided at a temperature between about 1000 C. and 1200 C.