Abstract: In order to avoid the risk of the damage of the continuity of matrix and the shedding of surface, a series of experiments were conducted to explore the cause of black holes appeared in the infiltrating metal layer of GCr15 chain pin by chromvanadizing heat treatment. The results show that the main reasons for the formation of black holes are the content of vanadium in the penetrating agent, the selection of catalysts and the airtightness of equipment. By modifying the proportion of permeating agent and using vacuum equipment to carry out heat treatment, the problem of black hole in permeating metal layer is solved, and the wear resistance of the pin shaft is greatly improved.

Key words: chain pin, chromvanadizing, black holes in infiltrating metal layer, airtightness