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CN-121992338-A - Die casting die nitrocarburizing process without white bright layer

CN121992338ACN 121992338 ACN121992338 ACN 121992338ACN-121992338-A

Abstract

The invention discloses a nitrogen-carbon co-permeation process of a die-casting die without a white bright layer, which comprises the following steps of quenching the die-casting die and tempering for a plurality of times, adjusting the hardness of the die-casting die, cleaning the surface of the die-casting die by using alcohol, placing the cleaned die-casting die into a gas nitriding furnace for vacuumizing, then introducing nitrogen, adding the nitriding furnace to 560 ℃, introducing ammonia and carbon dioxide into the nitriding furnace, adjusting the nitrogen potential, keeping the temperature of the die-casting die in a strong permeation period, adjusting the nitrogen potential, keeping the temperature of the die-casting die for 4-8 hours, keeping the die-casting die in a diffusion period, replacing the die-casting die with the nitrogen atmosphere, keeping the temperature for 2-4 hours, and discharging and air-cooling. The nitrogen-carbon co-permeation process for the die-casting die without the white bright layer provided by the invention eliminates the white bright layer, improves the permeation layer structure and improves the permeation layer depth so as to prolong the service life of the die.

Inventors

  • WU XIAOCHUN

Assignees

  • 上大鑫仑材料科技（上海）有限公司

Dates

Publication Date
20260508
Application Date
20260304

Claims (10)

  1. 1. The nitrocarburizing process for the die casting die without the white bright layer is characterized by comprising the following steps of: quenching and tempering the die-casting die for a plurality of times, and adjusting the hardness of the die-casting die; then cleaning the surface of the die-casting die by using alcohol; placing the cleaned die casting die into a gas nitriding furnace for vacuumizing, and then introducing nitrogen; Adding the nitriding furnace to 560 ℃, introducing ammonia and carbon dioxide into the nitriding furnace, adjusting nitrogen potential, and then preserving heat for 2-4 hours to enable the die casting die to be in a strong seepage period; adjusting nitrogen potential, and preserving heat for 4-8 hours to enable the die casting die to be in a diffusion period; and (3) replacing with nitrogen atmosphere, preserving heat for 2-4 hours, and discharging and air cooling.
  2. 2. A white-bright-layer-free die casting die nitrocarburizing process according to claim 1, wherein the die casting die is quenched and tempered three times.
  3. 3. The nitrogen-carbon co-permeation process of a die-casting die without a white bright layer according to claim 1, wherein the die-casting die is quenched and tempered for three times, specifically, after the die-casting die is heated and insulated, oil quenched to below Ms point, air cooled to room temperature, tempered for three times, and air cooled to room temperature for each tempering, and tempered for the next time.
  4. 4. The nitrogen-carbon co-cementation process of a die-casting die without a white bright layer as claimed in claim 1, wherein the die-casting die is quenched and tempered for several times, and the hardness of the die-casting die is adjusted to 44-50HRC.
  5. 5. The nitrogen-carbon co-permeation process of a die-casting die without a white bright layer according to claim 1, wherein the die-casting die after cleaning is placed in a gas nitriding furnace for vacuumizing, then nitrogen is introduced, specifically, the die is placed in the gas nitriding furnace for vacuumizing, then nitrogen is introduced to 15KPa.
  6. 6. The nitrogen-carbon co-permeation process of the die-casting die without the white bright layer according to claim 1, wherein the nitriding furnace is added to 560 ℃, ammonia and carbon dioxide are introduced into the nitriding furnace, the nitrogen potential is adjusted to 1.2-1.8, and the die-casting die is kept for 2-4 hours, so that the die-casting die is in a strong permeation period.
  7. 7. The process of claim 1, wherein the diffusion period is adjusted to a nitrogen potential of 0.4-0.6.
  8. 8. The nitrogen-carbon co-permeation process of a die casting die without a white bright layer according to claim 1, wherein the die is replaced by nitrogen atmosphere, is kept for 2-4 hours, particularly is replaced by nitrogen atmosphere, is cooled to 550 ℃, and is set to keep the temperature for 2-4 hours according to the effective thickness of the die.
  9. 9. The nitrogen-carbon co-permeation process of the die casting die without the white bright layer, which is characterized by using nitrogen atmosphere for replacement, preserving heat for 2-4 hours, specifically comprising cooling to 550 ℃, purging with nitrogen with the flow rate of 2.0L/h without introducing ammonia and carbon dioxide, and preserving heat for 2-4 hours.
  10. 10. The nitrogen-carbon co-permeation process of the die-casting die without a white bright layer according to claim 1, wherein the nitriding furnace is added to 560 ℃, ammonia gas and carbon dioxide are introduced into the nitriding furnace, the nitrogen potential is adjusted, and the die-casting die is kept for 2-4 hours, so that the die-casting die is in a strong permeation period, and the ratio of the introduced ammonia gas to the introduced carbon dioxide is 20:1.

Description

Die casting die nitrocarburizing process without white bright layer Technical Field The invention relates to a metal material surface treatment technology, in particular to a die casting die nitrocarburizing process without a white bright layer. Background The die is a manufacturing master, and a good die material can greatly improve the manufacturing efficiency and reduce the cost. With the proposal of Tesla integrated die casting concept, the market demand for die steel is also increasing. The conventional large die casting materials are 4Cr5Mo2V and 4Cr5MoSi1V, and the die casting materials can repeatedly contact with high-temperature molten aluminum alloy during service, so that thermal fatigue cracks, corrosion and the like are generated on the surfaces of the die casting materials. To improve the erosion resistance of the die-casting mold, it is common to perform nitrocarburizing to increase the surface hardness while maintaining the hardness of the matrix, so as to resist the erosion of the high-temperature molten aluminum alloy. The nitrocarburizing means that ammonia and carbon dioxide are introduced into a certain proportion at a certain temperature, active nitrogen atoms and active carbon atoms are obtained through decomposition, and meanwhile, the active nitrogen atoms and the active carbon atoms penetrate into the surface of the metal to form a carbon nitride layer. The seeping layer has the advantages of high hardness, high wear resistance, high corrosion resistance, high fatigue strength and the like. However, this treatment method has the disadvantage that hard and brittle pulse-like structures and white bright layers are produced, so that the impact load is not suitable, and the conventional large die casting machine can usually have a die locking force of 10000 tons, under which condition the market is faced with the need for nitriding without the white bright layers. Disclosure of Invention In view of the above-mentioned drawbacks of the prior art, the present invention aims to solve the technical problem that the existing nitrocarburizing process has hard and brittle pulse-like tissue and white and bright layers, and is not suitable for being subjected to impact load. The invention provides a nitrocarburizing process for a die casting die without a white bright layer, which eliminates the white bright layer, improves the structure of a seepage layer and improves the depth of the seepage layer so as to prolong the service life of the die. In order to achieve the above purpose, the invention provides a die casting die nitrocarburizing process without a white bright layer, which comprises the following steps: quenching and tempering the die-casting die for a plurality of times, and adjusting the hardness of the die-casting die; Then cleaning the surface of the die-casting die by using alcohol; placing the cleaned die casting die into a gas nitriding furnace for vacuumizing, and then introducing nitrogen; Adding a nitriding furnace to 560 ℃, introducing ammonia and carbon dioxide into the nitriding furnace, adjusting nitrogen potential, and preserving heat for 2-4 hours to enable the die casting die to be in a strong seepage period; adjusting nitrogen potential, and preserving heat for 4-8 hours to enable the die casting die to be in a diffusion period; and (3) replacing with nitrogen atmosphere, preserving heat for 2-4 hours, and discharging and air cooling. Further, the die casting die is quenched and tempered three times. Further, the die-casting die is quenched and tempered for three times, specifically, the die-casting die is heated and insulated, then is oil quenched to below Ms point, is air cooled to room temperature, is tempered for three times, and is air cooled to room temperature for each tempering, and then is tempered for the next time. Further, the die casting die is quenched and tempered for a plurality of times, and the hardness of the die casting die is adjusted to 48-50HRC. Further, placing the cleaned die casting die into a gas nitriding furnace for vacuumizing, then introducing nitrogen, specifically, placing the die into the gas nitriding furnace for vacuumizing, and then introducing nitrogen to 15KPa. Further, adding the nitriding furnace to 560 ℃, introducing ammonia and carbon dioxide into the nitriding furnace, adjusting the nitrogen potential to 1.2-1.8, and preserving the heat for 2-4 hours to enable the die casting die to be in a strong infiltration period. Further, the diffusion period adjusts the nitrogen potential to 0.4-0.6. Further, nitrogen atmosphere replacement is used, heat preservation is carried out for 2-4 hours, specifically nitrogen atmosphere replacement is used, the temperature is reduced to 550 ℃, and heat preservation is set for 2-4 hours according to the effective thickness of the die. Further, nitrogen atmosphere is used for replacement, the temperature is kept for 2-4 hours, the temperature is reduced to 550 ℃, ammonia gas and carbon dioxide