Patent ID: 8146340

Claim:
A link chain comprising: non-turning link ranks each having a plurality of first link plates each disposed in a width direction of said link chain and having a pair of pinholes; turning link ranks each having a plurality of second link plates each disposed in the width direction of said link chain and having a pair of bush holes; a bush disposed within each of the bush holes; pins linking said non-turning link ranks with said turning link ranks alternately by being inserted into the pinholes of said first link plates and the bushes of said second link plates; each first link plate not turning relatively with respect to each pin linking a respective non-turning rank with a respective turning rank so as to be fixed with respect to the pin thereby so linking the respective ranks; each second link plate being turnable relatively with respect to each pin linking a respective non-turning rank with a respective turning rank; a surface of each of said pins is coated by a metal carbide formed of at least one of chrome, vanadium, niobium, titanium, zirconium, tantalum, molybdenum and tungsten by means of cementation and having Vickers hardness of 1300 Hv or more; and each bush is molded into a seamless cylindrical shape by cold-forging carbon steel or alloy steel containing carbon by 0.2 wt % or more, is coated with a metal carbide formed of at least one of chrome, vanadium, niobium, titanium, zirconium, tantalum, molybdenum and tungsten by means of cementation and having Vickers hardness of 1300 Hv or more and is treated further by a quenching, tempering or isothermal transformation process.