from about 10 seconds to 5 minutes or more depending upon the specific carbonization temperature alternatively the stabilized filamentary material may be heated to a maximum temperature within the range of about 2000 u00b0 to 3100 u00b0 c in an inert atmosphere where it is maintained until substantial graphitization has occurred temperature gradients may be utilized wherein both carbonization and graphitization are accomplished in the same heating zone or the carbonization and graphitization zones may be distinct the equipment utilized to convert the stabilized filamentary material to a pyrolyzed carbonaceous fibrous material i e either an amorphous carbon or a graphitic carbon fibrous material may be varied as will be apparent to those skilled in the art it is essential that the apparatus be capable of producing the required temperature while excluding the presence of an oxidizing atmosphere in a preferred embodiment of the process a continuous length of a stabilized filamentary material is heated by use of an induction furnace in such a procedure the filamentary material may be passed in the direction of its length through a hollow graphite tube or other susceptor which is situated within the windings of the induction coil by varying the length of the graphite tube the length of the induction coil and the rate at which the filamentary material is passed through the graphite tube many apparatus.