WO2018103090A1 - High-nitrogen stainless bearing steel heat treatment process - Google Patents

Abstract

A high-nitrogen stainless bearing steel heat treatment process. The process comprises the following steps: S1: selecting a high-nitrogen steel liquid as a base raw material; S2: providing multiple sand pools, the temperatures of the sand pools being different; S3: annealing; S4: selecting sand pools of temperatures respectively between 350-400°C, 250-300°C, 150-200°C, 50-100°C, and 15-40°C; S5: preparing a surface coating agent; S6: preheating; S7: using a flame gun to burn a blank produced in step S6; S8: selecting an air cooler and immediately cooling with the air cooler the blank produced in step S7; and S9: air cooling the cooled blank of step S8. The process reduces resource wastage to a certain extent and increases the wear resistance, contact fatigue, and resilience of a bearing blank.

Description

Heat treatment process of high nitrogen stainless bearing steel Technical field

The invention relates to the technical field of heat treatment technology, and relates to a heat treatment process of high nitrogen stainless bearing steel.

Background technique

At present, bearings used in industries with very harsh working conditions, such as aerospace, require high fracture toughness, high contact fatigue life, and high wear resistance. They must also meet salt spray, mold and damp heat. The three-proof "test requirements, but the traditional high-carbon chromium stainless bearing steel used in the country can not meet the performance requirements. Since conventional steels inevitably produce large eutectic carbides, these carbides are unevenly distributed in a band shape, most of which precipitate on the grain boundaries, and cannot be eliminated during heat treatment, often grinding the bearing rings and The ultra-fine process has an adverse effect.

High-nitrogen steel is a new field of material research. Due to the material properties of high-nitrogen steel, its development and application have attracted extensive attention in various countries, but many problems remain unresolved, such as traditional high-nitrogen steel in casting. The process and the process of heat treatment will make the difference between the original parts of high-nitrogen steel and its own perfect state, and the reasons for these differences are not only the raw material ratio in high-nitrogen steel, but also the heat treatment process. One of the main reasons for this is that the heat treatment process under the prior art is relatively simple in the process of preheating, heating and cooling. Because there are many impurities inside the bearing originals, and these impurities are not easy to remove, the working environment of the bearing originals is relatively simple. Complex, the bearing original requirements are higher, the original in the ordinary processing and use process, will seriously reduce the quality of its use, resulting in a certain degree of wear resistance, contact fatigue and toughness, and the traditional heat treatment process exists A lot of energy is wasted, so a heat treatment process is needed to upgrade the high nitrogen steel shaft Processing quality stainless steel.

Summary of the invention

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat treatment process for a high nitrogen stainless bearing steel to solve the problems set forth in the above background art.

In order to achieve the above object, the present invention provides the following technical solution: a high nitrogen stainless bearing steel hot section Process, the process includes the following steps:

S1: selecting a high-nitrogen steel liquid as a base material, and casting a suitable mold to obtain a high-nitrogen stainless bearing steel original;

S2: setting multiple sand pools, the temperature of the sand pool is different;

S3: annealing, the original part in the step S1 is placed in the annealing furnace, the high temperature of the annealing furnace is set to 780-800 ° C, the low temperature is 550-600 ° C, and the original part is located in the annealing furnace for not less than 4.5 h;

S4: Select sand pools with temperatures between 350-400 ° C, 250-300 ° C, 150-200 ° C, 50-100 ° C, and 15-40 ° C, respectively, numbered 1, 2, 3, 4, and 5 sand Pool, and place the original in step S3 into the sand pool No. 1. When the temperature of the sand pool is lowered to the set temperature of the sand pool, take out the original and place it in the sand pool No. 2. Similarly, the original passes 1-5. Sand pool

S5: Preparation of surface smear: Select steel liquid with carbon content below 0.35% as base steel solution, fill it with nitrogen gas, keep the base steel liquid in a molten state and add Cr, Mn and Nb thereto, then use electromagnetic Stir for 25-30min, the surface coating agent is completed;

S6: Preheating, preheating the original obtained in step S4, first placing the original in the heating device, setting the temperature of the heating device between 150-300 ° C, preheating for 40-60 min, taking out the original and feeding it to the original The surface is sprayed with a surface coating agent, and the spraying process is sprayed, and the original piece is sprayed without a dead angle;

S7: The original piece obtained in the step S6 is burned by using a flame gun, and the burning time is between 30 min and 75 min. After the original piece is completely burned, it is taken out immediately;

S8: The cooling fan is selected, and the original piece obtained in the step S7 is immediately cooled by the cooling fan. After the original fan is purged by the cooling fan, the original is placed in the cooling liquid and cooled to below 60 ° C, and then taken out;

S9: air-cooling the cooling element in step S8, using the tempering furnace and setting the temperature of the tempering furnace to be between 130-170 ° C. After the temperature rises to the set temperature, the holding time is more than 45 min, and the original is taken out, and the high nitrogen is obtained. Stainless steel bearing steel heat treatment process is completed.

Preferably, the sand pool has a sand diameter of not less than three, and the sand diameters are 1 mm, 1.5 mm, and 2 mm, respectively.

Preferably, the Cr is contained in the surface coating agent in an amount of 13-15%, the content of Mn in the surface coating agent is ≤1.2%, and the content of Nb in the surface coating agent is ≤0.8%.

Preferably, the flame gun is disposed in not less than three groups, and the flame gun is uniformly disposed around the original to be processed.

Preferably, in the step S6, the original is located above the surface spreader furnace, and a circulating spray structure is adopted.

Compared with the prior art, the invention has the beneficial effects that the process of the invention is more scientific and reasonable, and the surface of the high-nitrogen stainless steel bearing can be rationalized by a reasonable process operation step, so that the bearing original part can be avoided by 0.5 mm or more. Better reinforcement treatment, and through the cooling and sand preservation effect of the sand pool, the heat treatment quality of the original can be improved. Compared with the traditional heat treatment process, the process can reduce the waste of resources to a certain extent, and can improve the wear resistance of the bearing originals. Sex, contact fatigue and toughness greatly improve the quality and longevity of bearing originals.

detailed description

The technical solutions in the embodiments of the present invention are clearly and completely described below. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts are within the scope of the present invention.

Embodiment 1

The invention provides a technical solution: a heat treatment process for a high nitrogen stainless bearing steel, the process comprising the following steps:

S1: selecting a high-nitrogen steel liquid as a base material, and casting a suitable mold to obtain a high-nitrogen stainless bearing steel original;

S2: setting multiple sand pools, the temperature of the sand pool is different;

S3: annealing, placing the original part in the step S1 in the annealing furnace, setting the high temperature of the annealing furnace to 800 ° C ° C, the low temperature is 550 ° C, and the original part is located in the annealing furnace for 4.5 h;

S4: Select sand pools with temperatures between 350 ° C, 250 ° C, 150 ° C, 50 ° C, and 15 ° C, respectively, numbered sand pools 1, 2, 3, 4, and 5, and place the originals in step S3 In the No. 1 sand pool, when the temperature of the sand pool is lowered to the set temperature of the sand pool, the original is taken out and placed in the No. 2 sand pool. Similarly, the original passes through the sand pool No. 1-5;

S5: Preparation of surface smear: Select steel liquid with carbon content of 0.35% as base steel solution, fill it with nitrogen gas, keep the base steel liquid in a molten state and add Cr, Mn and Nb thereto, then use electromagnetic stirring 25min, the surface smear was completed;

S6: preheating, preheating the original obtained in step S4, first putting the original into the heating device, setting the temperature of the heating device to 150 ° C, preheating for 40 min, taking out the original and spraying the surface coating agent on the surface of the original. The spraying process adopts spray spraying method to spray the original piece without dead angle;

S7: The original piece obtained in the step S6 is burned by using a flame gun, and the burning time is 30 minutes, and the original piece is completely burned, and then taken out immediately;

S8: The cooling fan is selected, and the original obtained in the step S7 is immediately cooled by the cooling fan. After the original fan is purged, the original is placed in the cooling liquid and cooled to 60 ° C, and then taken out;

S9: air-cooling the cooling element in step S8, using the tempering furnace and setting the temperature of the tempering furnace at 130 ° C, after the temperature rises to the set temperature, the holding time is 45 min, the original is taken out, and the high-nitrogen stainless bearing steel is heat-treated The process is completed.

Wherein: the sand pool has a diameter of not less than three, and the sand diameter is 1 mm, 1.5 mm and 2 mm, respectively, and the content of the Cr in the surface coating is 13%, and Mn is in the surface coating agent. The content is 1.2%, the content of Nb in the surface coating agent is 0.8%, the flame gun is set in 3 groups, and the flame gun is uniformly disposed around the original to be processed, and the original part in the S6 step is located above the surface coating agent furnace. A circulating spray structure is used.

Embodiment 2

The invention provides a technical solution: a heat treatment process for a high nitrogen stainless bearing steel, the process comprising the following steps:

S1: selecting a high-nitrogen steel liquid as a base material, and casting a suitable mold to obtain a high-nitrogen stainless bearing steel original;

S2: setting multiple sand pools, the temperature of the sand pool is different;

S3: annealing, the original part in the step S1 is placed in the annealing furnace, the annealing furnace has a high temperature of 790 ° C, a low temperature of 580 ° C, and the original part is located in the annealing furnace for 5 hours;

S4: Select sand pools with temperatures between 370 ° C, 270 ° C, 170 ° C, 80 ° C, and 25 ° C, respectively, with sand pools of 1, 2, 3, 4, and 5, and place the originals in step S3. In the No. 1 sand pool, when the temperature of the sand pool is lowered to the set temperature of the sand pool, the original is taken out and placed in the No. 2 sand pool. Similarly, the original passes through the sand pool No. 1-5;

S5: Preparation of surface smear: Select a molten steel containing 0.3% carbon as the base steel, fill it with nitrogen, keep the base molten steel in a molten state and add Cr, Mn and Nb thereto, then use electromagnetic stirring. 27min, the surface smear was completed;

S6: Preheating, preheating the original obtained in step S4, first placing the original in the heating device, setting the temperature of the heating device to 230 ° C, preheating for 50 min, taking out the original and applying the surface to the original surface. Spraying process using spraying spray method to spray the original piece without dead angle;

S7: The original piece obtained in the step S6 is burned by using a flame gun, and the burning time is between 50 minutes. After the original piece is completely burned, it is taken out immediately;

S8: The cooling unit is selected, and the original part obtained in step S7 is immediately cooled by the cooling fan. After the original part is purged by the cooling fan, the original piece is placed in the cooling liquid and cooled to 650 ° C, and then taken out;

S9: The cooling element in the step S8 is air-cooled, and the tempering furnace is used to set the temperature of the tempering furnace at 155 ° C. After the temperature rises to the set temperature, the holding time is 50 min, and the original piece is taken out, and the high nitrogen stainless bearing steel is obtained. The heat treatment process is completed.

Wherein: the sand pool has a diameter of not less than three, and the sand diameter is 1 mm, 1.5 mm and 2 mm, respectively, and the content of the Cr in the surface coating is between 14%, and the Mn is applied on the surface. The content is 1%, the content of Nb in the surface coating is 0.7%, the flame gun is set in 4 groups, and the flame gun The original is to be evenly disposed around the original to be processed, and the original in the step S6 is located above the surface spreader furnace, and a circulating spray structure is adopted.

Embodiment 3

The invention provides a technical solution: a heat treatment process for a high nitrogen stainless bearing steel, the process comprising the following steps:

S1: selecting a high-nitrogen steel liquid as a base material, and casting a suitable mold to obtain a high-nitrogen stainless bearing steel original;

S2: setting multiple sand pools, the temperature of the sand pool is different;

S3: annealing, the original part in the step S1 is placed in the annealing furnace, the annealing furnace has a high temperature of 800 ° C, a low temperature of 600 ° C, and the original part is located in the annealing furnace for 5.5 h;

S4: Select sand pools with temperatures between 400 ° C, 300 ° C, 200 ° C, 100 ° C, and 40 ° C, respectively, with sand pools 1, 2, 3, 4, and 5, and place the originals in step S3. In the No. 1 sand pool, when the temperature of the sand pool is lowered to the set temperature of the sand pool, the original is taken out and placed in the No. 2 sand pool. Similarly, the original passes through the sand pool No. 1-5;

S5: Preparation of surface smear: Select steel liquid with carbon content below 0.29% as base steel solution, fill it with nitrogen gas, keep the base steel liquid in a molten state and add Cr, Mn and Nb thereto, then use electromagnetic Stir for 30min, the surface coating agent is completed;

S6: preheating, preheating the original obtained in step S4, first placing the original in the heating device, setting the temperature of the heating device between 300 ° C, preheating for 60 min, taking out the original and applying the surface to the original surface. Spraying process using spraying spray method to spray the original piece without dead angle;

S7: The original piece obtained in the step S6 is burned by using a flame gun, and the burning time is between 75 minutes. After the original piece is completely burned, it is taken out immediately;

S8: The cooling unit is selected, and the original part obtained in step S7 is immediately cooled by the cooling fan. After the original part is purged by the cooling fan, the original piece is placed in the cooling liquid and cooled to 68 ° C, and then taken out;

S9: air-cooling the cooling element in step S8, using the tempering furnace and setting the temperature of the tempering furnace at Between 170 ° C, after the temperature rises to the set temperature, the holding time is 55 min, the original is taken out, and the heat treatment process of the high nitrogen stainless bearing steel is completed.

Wherein: the sand pool has a diameter of not less than three, and the sand diameter is 1 mm, 1.5 mm and 2 mm, respectively, and the content of the Cr in the surface coating agent is between 15%, and the Mn is applied on the surface. The content of the material is 1.1%, the content of Nb in the surface coating agent is 0.75%, the flame gun is set to 5 sets, and the flame gun is uniformly disposed around the original to be processed, and the original part in the S6 step is located in the surface coating agent furnace. Above, a circulating spray structure is used.

The high-nitrogen bearing stainless steel prepared by the three sets of examples was processed into original parts, and the bearing originals were installed using the same specifications and simultaneously subjected to rotational wear, breaking strength and contact fatigue test. The experimental data are as follows:

Group	Fracture toughness	Wear resistance	Contact fatigue
Embodiment 1	+	++	++
Embodiment 2	+++	++++	+++
Embodiment 3	+	+	++

Based on the basic comparison of traditional stainless steel bearings, the fracture toughness, wear resistance and contact fatigue of conventional stainless steel bearings are set to "+".

It can be seen from the above table data that the three sets of embodiments have better functional improvement than the conventional stainless steel bearings, and the second embodiment has the best effect.

Compared with the traditional heat treatment process, the process can better control the temperature of the bearing original by the temperature reduction and heat preservation treatment of the sand pool, improve the heat treatment quality of the bearing original, and cooperate with Cr by burning on the surface. Mn and Nb can improve the nitrogen content of the bearing original surface, and better maintain the bearing original to avoid structural toughness of 0.5mm or more.

In general, the process optimizes the heat treatment process of the traditional high-nitrogen bearing stainless steel, and achieves resource saving to a certain extent, greatly improving the fracture toughness, wear resistance and contact fatigue of the bearing original. Extensive market application prospects are conducive to promotion.

While the embodiments of the present invention have been shown and described, it will be understood by those skilled in the art The scope of the invention is defined by the appended claims and their equivalents.

Claims (5)

1. A high-nitrogen stainless bearing steel heat treatment process, characterized in that the process comprises the following steps:

   S1: selecting a high-nitrogen steel liquid as a base material, and casting a suitable mold to obtain a high-nitrogen stainless bearing steel original;

   S2: setting multiple sand pools, the temperature of the sand pool is different;

   S3: annealing, the original part in the step S1 is placed in the annealing furnace, the high temperature of the annealing furnace is set to 780-800 ° C, the low temperature is 550-600 ° C, and the original part is located in the annealing furnace for not less than 4.5 h;

   S4: Select sand pools with temperatures between 350-400 ° C, 250-300 ° C, 150-200 ° C, 50-100 ° C, and 15-40 ° C, respectively, numbered 1, 2, 3, 4, and 5 sand Pool, and place the original in step S3 into the sand pool No. 1. When the temperature of the sand pool is lowered to the set temperature of the sand pool, take out the original and place it in the sand pool No. 2. Similarly, the original passes 1-5. Sand pool

   S5: Preparation of surface smear: Select steel liquid with carbon content below 0.35% as base steel solution, fill it with nitrogen gas, keep the base steel liquid in a molten state and add Cr, Mn and Nb thereto, then use electromagnetic Stir for 25-30min, the surface coating agent is completed;

   S6: Preheating, preheating the original obtained in step S4, first placing the original in the heating device, setting the temperature of the heating device between 150-300 ° C, preheating for 40-60 min, taking out the original and feeding it to the original The surface is sprayed with a surface coating agent, and the spraying process is sprayed, and the original piece is sprayed without a dead angle;

   S7: The original piece obtained in the step S6 is burned by using a flame gun, and the burning time is between 30 min and 75 min. After the original piece is completely burned, it is taken out immediately;

   S8: The cooling fan is selected, and the original piece obtained in the step S7 is immediately cooled by the cooling fan. After the original fan is purged by the cooling fan, the original is placed in the cooling liquid and cooled to below 60 ° C, and then taken out;

   S9: air-cooling the cooling element in step S8, using the tempering furnace and setting the temperature of the tempering furnace to be between 130-170 ° C. After the temperature rises to the set temperature, the holding time is more than 45 min, and the original is taken out, and the high nitrogen is obtained. Stainless steel bearing steel heat treatment process is completed.
2. The heat treatment process for a high-nitrogen stainless bearing steel according to claim 1, wherein the sand pool has a diameter of not less than three, and the sand diameters are 1 mm, 1.5 mm, and 2 mm, respectively.
3. The heat treatment process for a high-nitrogen stainless bearing steel according to claim 1, wherein the Cr content in the surface coating agent is between 13-15%, and the content of Mn in the surface coating agent is ≤1.2. %, Nb content in the surface coating agent ≤ 0.8%.
4. The heat treatment process for a high-nitrogen stainless bearing steel according to claim 1, wherein the flame gun is disposed in not less than three groups, and the flame gun is uniformly disposed around the original to be processed.
5. The heat treatment process for a high-nitrogen stainless bearing steel according to claim 1, wherein the original member is located above the surface spreader furnace in the step S6, and adopts a circulating spray structure.