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Nitriding and Nitrocarburization

What is nitriding and nitrocarburizing?

These processes are thermochemical processes that improve the surface properties of finished or semi-finished products and are carried out with low temperature and low distortion. Material surface, material composition, surface cleanliness, equipment and process parameters used are extremely important parameters in the formation of the final properties that gas nitration and gas nitrocarburizing processes will give to the product.

Gas Nitrocarburizing

Gas Nitrocarburizing process times vary between 30 minutes and 7 hours. In the gas nitration process, besides the ammonia gas given to the environment, carbon dioxide is given to the environment in this process. During the process, a thin layer of iron nitrocarbide enters from the surface of the part by diffusion with the effect of nitrogen and carbon temperature obtained in the fragmentation frit. The process is divided into ferritic nitrocarburizing at 560-580 degrees or austenitic nitrocarburizing at 590-720 degrees. Since the temperature applied in the austenitic nitrocarburizing process is higher, the risk of waste is higher.

The white layer formed after the gas nitrocarburizing process significantly increases the corrosion resistance of the material. In addition, the corrosion resistance of the material can be further increased by forming an iron oxide layer (1-3 microns) on the surface of the material with the post-oxidation process applied after the nitrocarburizing process.

Gas Nitriding

The gas nitriding process is a process that can last up to a maximum of 100 hours at temperatures between 490-560 C. In the gas nitration process, the ammonia gas in the process is broken down to form the nitrogen gas in atomic form and the nitrogen diffuses to the surface of the material with its effect on temperature. The amount (depth) of diffused nitrogen interacts with the nitride forming alloy elements in the chemical structure of the material to form nitride precipitates. As a result of the nitriding process, a layer of iron nitride, also called a white layer, is formed on the surface of the material (approximately 5-30 microns). This layer increases the corrosion and wear resistance of the material. The area between the white layer and the core is called the diffusion layer and contains a large amount of nitride deposits. The diffusion layer especially increases the fatigue resistance of the material and improves the wear resistance.

The mechanical properties that gas nitriding and gas nitrocarburizing processes add to the material are quite similar. The most important difference in the choice of process is that gas nitriding is a very long process (cost) but is done at low temperature (very low distortion), while looking at gas nitrocarburizing, the process time is short (low cost) but relatively high temperature. (more distortion).

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Nitriding Process at Önerler

Gas nitriding furnaces are used for nitriding processes in our company.

  • Gas nitriding, gas nitrocarburizing, and post oxidation processes are all performed in our company.

  • All 3 nitriding furnaces with charging capacities of 600 kg and 2000 kg are German origin IPSEN brand.

  • With the NitroProf program in our furnaces, temperature, time and gas flows that are vital for the process are automatically controlled and recorded.

In our company, which has very important know-how in gas nitriding and gas nitrocarburizing processes, which we have been applying since 2007, we offer our customers the best quality with our expert staff and state-of-the-art equipment.

Benefits of the processes

  • High surface hardness

  • High wear resistance
  • Low friction coefficient

  • High corrosion resistance

  • High fatigue resistance

  • Minimum distortion after the process

Steels Applicable to Processes

  • Crankshafts (fatigue - wear resistance)

  • Gas springs (high wear resistance, corrosion resistance and aesthetic appearance with post-oxidation process after nitration)

  • Hot forging and form molds

  • Washers (Low friction coefficient)

  • Springs (High fatigue resistance

  • Aluminum injection molds

  • Plastic injection molds (Wear resistance, adhesion prevention, and high fatigue resistance)

    1010 250 - 350 HV1

    1020 250 - 350 HV1

    1030 300 - 400 HV1

    1040 350 - 450 HV1

    1050 450 - 550 HV1

    1060 450 - 550 HV1

    4130 500 - 600 HV1

    4140 550 - 650 HV1

    4340 550 - 650 HV1

    8620 500 - 600 HV1

    1.7131 550 - 650 HV1

    1.2714 700 - 800 HV1

    1.2343 950 - 1100 HV1

    1.2344 1000 - 1150 HV1

    1.2367 1000 - 1150 HV1

    1.8519 800 - 900 HV1

    1.8550 950 - 1100 HV1

Problems That May Occur After The Procedures

Since nitriding processes are carried out at lower temperatures than other processes, the problem of distortion is much less. Despite this situation, very small size variations can be seen in finished and nitrided materials.

Since the nitriding process is a surface treatment, material cleaning is extremely important. Cutting fluid, cooling oil, etc. that may come from processes such as machining and grinding. impurities affect the process visually and metallurgically negatively. Since the mechanical properties to be obtained as a result of the nitriding process are directly related to the alloying elements of the steel used, the performance values expected from the material cannot be achieved as a result of a wrong steel selection.