One. Application of industrial gases in heat treatment:
1. Hardening：In metal processing, heat treatment is used to increase the hardness and strength of steel. The hardening effect is achieved by heating the steel to a critical temperature and then cooling it rapidly, which creates a martensite structure. This heat treatment usually uses nitrogen or hydrogen as a protective atmosphere and water or oil as the cooling medium.
2. Quenching：Quenching is a heat treatment method that changes the properties of a material by rapidly cooling it. In an industrial furnace, materials are heated to the appropriate temperature and then rapidly cooled, often using water, oil, or a gaseous medium to rapidly cool the material. This process can be used to increase the hardness, strength and wear resistance of materials.
3. Annealing：Annealing is a heat treatment method by heating a material to a high temperature and then cooling it slowly. Annealing can be used to relieve stress, improve the toughness and processability of materials, and adjust grain size and structure. During the annealing process, commonly used atmosphere control gases include nitrogen, hydrogen and mixed gases.
4. Welding：During metal welding, heat treatment is used to relieve stress on the welded joint and improve its mechanical properties. Welded materials often undergo an annealing or aging treatment to relieve stress and increase the strength of the weld area.
5. Nitriding：Nitriding is a heat treatment method in which materials are exposed to nitrogen or ammonia at high temperatures to form a nitride layer on their surface. This layer can increase the hardness, wear resistance and corrosion resistance of the material and increase the service life of the material. Nitriding is commonly used on materials such as tool steel, stainless steel and engineering steel.
Two. Commonly used industrial gases in industrial furnace heat treatment:
Nitrogen (N2): Nitrogen is widely used for atmosphere control during heat treatment. It acts as a protective atmosphere to prevent oxidation of materials and the formation of an oxide layer on the surface. In addition, nitrogen can be used for rapid cooling during cooling and quenching.
Hydrogen (H2): Hydrogen is commonly used in annealing and reduction reactions. It can reduce oxides on the surface of materials and improve the purity and strength of metals.
Oxygen (O2): Oxygen is often used in combustion processes to provide oxygen to support combustion reactions. It is used for heating and oxidation in some heat treatments.
Methane (CH4): Methane is a commonly used fuel gas that can be used to provide combustion heat in furnaces.
Ethylene (C2H4): Ethylene is a commonly used fuel gas. It is often used in the heat treatment process of high-temperature furnaces to provide the heat source required for high-temperature combustion.
Argon (Ar): Argon is mainly used as an inert gas and is often used in protective atmospheres. It can prevent oxidation and nitridation of the material surface, and is especially suitable for processes such as welding, annealing and sintering during high-temperature processing.
Ammonia (NH3): Ammonia is commonly used in atmosphere control and nitriding processes in heat treatment. It can provide active nitrogen through a reaction to form a nitride layer on the surface of the material, thereby increasing hardness and wear resistance.
Carbon monoxide (CO): Carbon monoxide is a commonly used reducing gas used to reduce metal oxides in heat treatments. It can reduce the content of oxides and improve the surface quality and performance of materials.
Carbon dioxide (CO2): Carbon dioxide is commonly used in cooling and quenching processes. It can control the hardening and phase transformation of materials through rapid cooling to achieve the required physical and mechanical properties.
Hydrogen-nitrogen mixed gas (H2/N2): Hydrogen-nitrogen mixed gas is often used in annealing and reduction processes. It can provide a reducing atmosphere, reduce the oxide content on the metal surface, and improve the purity and performance of the material.
Nitrogen-hydrogen mixed gas (N2/H2): Nitrogen-hydrogen mixed gas is often used in nitriding treatment and reduction reactions. By adjusting the ratio of nitrogen and hydrogen in the mixed gas, the atmosphere control and reaction conditions can be adjusted to meet the requirements of specific material processing.
