A heat treating furnace is disclosed for nitride case hardening and gas cooling a stationary workload in the same furnace which is comprised of a single chamber and an access door. The chamber is segregated into an outer portion and an inner portion, with the inner portion being adapted to receive the workload to be nitride case hardened through the access door. The inner portion is surrounded by graphite insulation to retain the gas used to nitride case harden the workload. The inner portion further includes a plurality of graphite resistance heating elements and a plurality of graphite plates juxtaposed in near proximity to the graphite resistance heating elements forming a conduit or plenum between them. The inner portion further includes a fan assembly including a graphite radial fan wheel adapted to circulate the nitriding gas within the inner portion and through the conduit to provide uniform nitride case hardening of the workload.