TH62772A - Methods of vacuum carbonitride - Google Patents

Abstract

DC60 (30/01/46) A method for vacuum carbonitriding, which includes: vacuum carburizing the workpiece in a heat treatment furnace under reduced pressure by supplying carburizing gas to the furnace, which has been heated to a predetermined carburizing temperature; stopping the carburizing gas supply to allow carbon diffusion in the workpiece under reduced pressure; and performing the nitriding process on the workpiece by supplying nitriding gas to the furnace under reduced pressure after the furnace temperature has been lowered. The desired heat treatment qualities, such as hardness, effective box depth, toughness, etc., can be achieved in a short time with remanufacturing capabilities, even in the case of workpieces made of low-grade steel or hardened steel boxes. The vacuum carbonitriding method includes: vacuum carburizing the workpiece in a heat treatment furnace. Under reduced pressure, carburizing gas is introduced into a furnace heated to a predetermined carburizing temperature. The carburizing gas supply is then stopped to allow carbon diffusion into the workpiece under reduced pressure. Nitriding of the workpiece is then performed by introducing nitriding gas into the furnace under reduced pressure after the furnace temperature is lowered. The desired heat treatment qualities, such as hardness, effective box depth, toughness, and similar attributes, can be achieved in a short time, along with remanufacturing capabilities, even in cases of workpieces made from lower-grade steel or hardened steel boxes.

Claims (3)

1. The vacuum carbonitriding method consists of: vacuum carbonitriding on the treated material in a heat treatment furnace under reduced pressure by supplying carburizing gas to a furnace heated to a predetermined carburizing temperature; diffusion of carbon on the treated material by stopping the supply of carburizing gas while maintaining the carburizing temperature to allow carbon to diffuse into the treated material under reduced pressure for a predetermined period based on the desired box depth; and nitriding on the treated material by supplying nitriding gas to the furnace under reduced pressure after the furnace temperature has been reduced. 2. The vacuum carbonitriding method under claim 1, which involves the use of a gas mixture of ethylene and hydrogen as the carburizing gas. 3. A vacuum carbonitriding method pursuant to claim 1 or 2, comprising control of the resulting box depth of the treated material after suspension, which is performed post-nitridation based on the nitriding time.