Salt Bath Nitrocarburizing

Our Salt Bath Nitrocarburizing(SBNC) is a low-temperature and environment-friendly carburizing permeation treatment widely used in industrial fields in the world. The workpiece is immersed in a 580°C salt bath with rich [N] and [C] atoms. In this way, nascent [N] and [C] atoms in the salt bath penetrate into the inner part of parts and form a compound layer on the surface of parts and a diffusion lay under the compound layer. Different processes can be selected depending on customer requirements.

Definition of process 

Setting: Place the product to be processed on jigs in a specific manner.

Preheating: ①Dry the residual moisture on the part to prevent salt splash due to evaporation of moisture when the product is put into the furnace.

                     ②Reduce the temperature difference when the product is put into the furnace to reduce the thermal deformation. 

SBNC:  SBNC makes separated live [N] and [C] atoms from 550 ~600°C salt bath  penetrate into the surface of the product to form a component layer of ε-FexN ( x=2~3) and a diffusion layer. The component layer of ε phase has high hardness and abrasion resistance, while the diffusion layer processes good fatigue strength. 

OB: OB refers to oxidizing salt bath with rich nascent [O] atoms. If the product is treated by OB after SBNC, black oxidation film (Fe₃O₄),an even and dense layer can form on the surface to significantly improve its corrosion resistance. The color and thickness of such oxidation film will increase with temperature and time.

Post-processing: The purpose is to remove dust and stain on the surface after SBNC, and glaze the surface. The  available post-processing methods include: grinding, polishing, sand blasting, shot blasting, etc.

Process performance and application

After Salt Bath Nitrocarburizing, a layer of Fe [C, N] is formed on the workpiece surface, which has high hardness, good wear resistance and corrosion resistance. Due to the penetration of  [N] atoms, the workpiece surface results in residual compressive stress, which can significantly improve the fatigue strength of the workpiece, and with an increase in the cooling rate of soft nitriding, the other aspects of performance (such as bending strength) are also increased. 

After Salt Bath Nitrocarburizing, a layer of Fe₃O₄-based black oxide film will be formed on the workpiece surface if processed by oxidation salt-bath; the film cannot only improve the corrosion resistance of the workpiece, but also reduce the friction coefficient of the workpiece surface  with a strong lubricity. The Salt Bath Nitrocarburizing process is suitable for carbon steel, low, medium and high alloy steel, cast iron and iron-based power metallurgy materials. It is widely used for wear-resisting parts, tools and dies with thin infiltration layer, small load and demanding deformation.

Automobiles: relevant parts for drive system, brake system, turbocharging, Air-conditioning compressor, vehicle door, engine 

Home appliance and OA appliance: relevant parts for copier, printer and washer 

Others: relevant parts for plant and equipment, power-driven tools, medical device, textile machines, appliance and switches

Photos of equipment

Examples of products