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What is the nitriding process of aluminum extrusion die?

What is the nitriding process of aluminum extrusion die?

Answer:

Aluminum extrusion die manufacturing process, extrusion die process is generally as follows:Put forward the mold task (profile drawing)HereDie design for forging blank, annealing and extrusionDown hereTurning procedure checkDown hereCoarse grinding plane, crossed through NC program tape or tapeHereDrilling and millingHereTo test the electrode machining EDM..HereHeat treatment line cutting processHereInspection and correction of grindingHereExtrusion honingHereExtrusion, mold testing and fixing the nitriding treatment
The principle of nitridation:Gas nitrocarburizing, that is gas nitrocarburizing, refers to low temperature nitrocarburizing based on gas nitriding and carburizing. Commonly used media have 50% ammonia, +50% endothermic gas (Nitemper method); 35%-50% ammonia, +50-60% exothermic gas (Nitroc method) and ammonia through the drip ethanol or formamide and so on. In soft nitriding, because of the high solubility of carbon atoms in the epsilon phase, the soft nitrided surface is a common compound of carbon and nitrogen, which is good in toughness and wear resistant.In the process of gas nitrocarburizing, due to the extremely low solubility of carbon atoms, it quickly reaches saturation state and precipitates many super micro cementite points. These cementite particles, as the core of the crystallization of nitrides, contribute to the formation of nitrides. When the surface nitrogen concentration reaches a certain level, the epsilon phase is formed, while the carbon solubility of the epsilon phase is very high, which in turn accelerates the dissolution of carbon.After gas nitrocarburizing, its structure is composed of epsilon phase, gamma phase and nitrogen containing cementite Fe3 (C, N), carbon will reduce the diffusion rate of nitrogen, so the thermal stress and the stress of the tissue are hard, the nitriding is large and the layer is thinner. But at the same time, because the soft nitride layer does not exist. Therefore, the nitride layer, better toughness than hard nitriding
Nitriding process:The main process parameters of gas nitrocarburizing are nitriding temperature, nitriding time, and nitriding atmosphere.The gas soft nitriding temperature is usually 560-570 DEG C, because the nitrided layer has the highest hardness at this temperature. The nitriding time is usually 3-4 hours, because the hardness of the compound layer reaches the maximum at 2-3 hours after penetration, while the depth of the nitrided layer increases slowly with time. The nitriding atmosphere is determined by the rate of ammonia decomposition and the rate of dripping of the carbonaceous penetrant.

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