conventional example 2 in which a pin having a surface layer of chromium carbide was used however as shown in fig2 in oxidized deteriorated oil the elongation of the roller chain of the invention was about u2154 the elongation of the chain of conventional example 2 furthermore as shown in fig4 the elongation properties of the roller chain of the invention are superior to those of conventional examples 1 and 2 in soot containing oil these test results lead to the conclusion that in the roller chain of the invention wear resistance in oxidized deteriorated oil is significantly improved since vanadium carbide has corrosion resistance superior to that of chromium carbide in the deteriorated oil environment furthermore since the roller chain pins having a vanadium carbide layer are harder than those subjected to carburization heat treatment and also harder than those having a chromium carbide layer the wear resistance properties of the roller chain in accordance with the invention are superior in soot containing oil heretofore surface treatment by the formation of a vanadium carbide layer was not recognized to be significantly advantageous as compared with other surface treatments such as carburization heat treatment and the formation of chromium carbide layer however vanadium carbide has proven to be highly superior as a coating material for the pins of a roller chain used under severe conditions such as in oxidized deteriorated oil or in soot containing oil the vanadium.