CN110846552A - Forging method of martensitic stainless steel main shaft - Google Patents

Abstract

The invention relates to a forging method of a martensitic stainless steel main shaft, which comprises the steps of adopting a special heating mode to control the temperature of an electroslag ingot, firstly placing the remelted DIN1.4122 electroslag ingot in a furnace with the temperature of 650 +/-10 ℃ for heat preservation, then placing the furnace in a heating furnace for rapidly heating to the forging temperature of 1200 +/-10 ℃, avoiding generating tissue stress and reducing the risk of forging cracking; the economic cost and the time cost of heating production before forging are saved, the production efficiency is improved, the deformation amount and the deformation speed of each pass are strictly controlled, and the main deformation temperature is controlled to be 830-1150 ℃; in order to avoid the temperature rise inside the forging caused by forging deformation, delta-ferrite is generated inside the forging: on one hand, the deformation of the main deformation pass of the oil press is controlled to be 80-150 mm, and the forging is carried out in a pulling or pushing mode, so that the local over-high temperature rise is avoided; on the other hand, the oil press is fully utilized to transfer the forging clearance of the precision forging machine, air cooling temperature control is carried out, the temperature of the center of the forge piece is reduced, the phenomenon that the temperature rise inside the forge piece is too high in the rapid forging process of the precision forging machine is avoided, forging in a two-phase region is successfully avoided, forging cracking is reduced, and the impact power value after tempering is improved.

Description

Forging method of martensitic stainless steel main shaft

Technical Field

The invention belongs to the technical field of steel material manufacturing process control, and particularly relates to a forging method of a martensitic stainless steel main shaft.

Background

The specification of the esterification reactor forging is large, the adopted DIN1.4122 material belongs to high-chromium martensitic stainless steel, the material has poor thermal conductivity, large deformation resistance and poor plasticity, the material is extremely easy to crack in the forging and forming process of the traditional oil press, and the delta-ferrite structure generated in the production process seriously influences the impact energy index after quenching and tempering. Therefore, aiming at the problems of serious surface cracking and low impact value after quenching and tempering of the DIN1.4122 shaft parts, the special production and manufacturing process is adopted, so that the qualified product quality is ensured, the production efficiency can be greatly improved, and the production cost is reduced.

Disclosure of Invention

The invention aims to solve the problems of cracking and improper structure, low impact energy after quenching and tempering and the like of the main shaft forge piece for the martensitic stainless steel DIN1.1422 esterification reactor produced in the prior art, and provides the forging method of the martensitic stainless steel main shaft, which solves the forging problems, improves the quality requirement of the forge piece, meets the requirements of the quenched and tempered structure and mechanical property, and improves the product percent of pass and production efficiency.

In order to achieve the purpose, the invention adopts the following technical scheme:

a forging method of a martensitic stainless steel main shaft is characterized by comprising the following specific steps:

step 1), selecting materials and making steel by adopting an electric furnace smelting and vacuum refining mode, stirring argon in the whole refining process and pouring under the protection of argon; the internal control chemical components in the refining process are calculated according to the weight percentage: 0.33 to 0.43 percent of C, 15.00 to 17.50 percent of Cr, 0.80 to 1.30 percent of Mo, less than or equal to 1.00 percent of Mn, less than or equal to 1.00 percent of Ni, less than or equal to 1.00 percent of Si, less than or equal to 0.040 percent of P, and less than or equal to 0.015 percent of S; after degassing, on-line hydrogen determination and oxygen determination are carried out, the content of [ H ] is controlled to be less than or equal to 1.5ppm, the content of [ O ] is controlled to be less than or equal to 5ppm, and the content of nitrogen in a gas sample is analyzed to be less than or equal to 90 ppm. High-quality scrap steel is selected as a material, 0.5-1.5 tons of carburant and 0.5-1.5 tons of lime are added into the furnace in advance before feeding, the [ P ] is reduced to be below 0.005 percent by utilizing the advantage of low temperature of molten steel in the early stage of oxidation, and steel retaining and slag retaining operation is adopted for tapping; the vacuum degassing is sufficient, the holding time is more than or equal to 20 minutes under the condition that the pressure is less than or equal to 0.7mbar, and the gas and the nonmetallic inclusion in the molten steel are removed to the maximum extent.

Step 2), remelting the cast martensitic stainless steel spindle electroslag ingot, placing the remelted martensitic stainless steel spindle electroslag ingot in a furnace at 650 +/-10 ℃ for heat preservation for 4 hours, then, quickly heating the ingot in the furnace to the forging temperature of 1200 +/-10 ℃ after the furnace is rotated to perform heat preservation at 800-850 ℃ for 3 hours;

step 3), feeding the martensitic stainless steel spindle electroslag ingot heated to the forging temperature into a 5000-ton oil press for drawing, and controlling the deformation of the main deformation pass of the oil press to be 80-150 mm; hammering the same position once in the deformation process of each pass, performing pull forging on the next position after pressing the hammer once at the same position in the deformation process, after the pass forging of the whole forge piece is finished, starting next pass forging from the other end, forging in a pull forging or push forging mode, avoiding repeated hammering forging at the same position, causing overhigh local temperature rise of the forge piece, generating delta-ferrite, causing forging cracking and influencing the structure after forging, further reducing the impact power after tempering, and stopping forging after the forging is finished to phi 550mm on an upper flat V anvil and a lower V anvil of an oil press;

and 4) feeding the elongated martensitic stainless steel spindle electroslag ingot into a precision forging machine for forging and forming, and meanwhile, performing air cooling temperature control on the forged piece by utilizing a forging gap formed by rotating the precision forging machine by using an oil press, namely performing air cooling temperature control on the forged piece after the oil press finishes forging, and performing forging forming on the precision forging machine after the surface temperature of the forged piece is air cooled to 870-900 ℃ so as to reduce the core temperature of the forged piece, avoid overhigh temperature rise inside the forged piece in the quick forging process of the precision forging machine to generate delta-ferrite, successfully avoid forging in a two-phase region, reduce forging cracking and improve the impact power value after quenching and tempering.

The technical scheme of the invention has the following positive effects:

the invention adopts a unique forging process control method to avoid delta-ferrite generated in the forge piece due to temperature rise caused by forging deformation. Strictly controlling the deformation and deformation speed of each pass to control the main deformation temperature at 930-1150 ℃. On one hand, the deformation of the main deformation pass of the hydraulic press is controlled to be 80-150 mm, and the next position is drawn and forged after one time of hammering at the same position in the deformation process of each pass, namely one time of hammering at the same position in the deformation process; and after the forging of the whole forging piece in the first pass is finished, starting the forging of the next pass from the other end. The phenomenon that the local temperature rise of a forge piece is too high due to multiple times of hammer forging at the same position is avoided; on the other hand, the forging clearance of the oil press rotating precision forging machine is fully utilized to carry out air cooling temperature control, the temperature of the center of the forge piece is reduced, and the overhigh temperature rise inside the forge piece in the rapid forging process of the precision forging machine is avoided. Thereby successfully avoiding forging in a two-phase region, reducing forging cracking and improving the impact power value after tempering.

The invention solves the problems of cracking of the forged spindle piece for the martensitic stainless steel DIN1.4122 esterification reactor, influence of delta-ferrite on impact energy and the like, ensures the product quality, has small machining allowance, high production efficiency, reduced production cost, good forged piece forging permeability, uniform mechanical properties of all parts, long service life and more economic and scientific production process.

Drawings

FIG. 1 is a drawing of a DIN1.4122 spindle forging in mm dimensions according to an embodiment of the invention.

FIG. 2 is a graph showing the pre-forging heating specification of a DIN1.4122 spindle in accordance with an embodiment of the invention.

Detailed Description

The invention will be further illustrated and described with reference to specific examples.

Example 1: a forging method of a martensitic stainless steel main shaft takes a main shaft forging with the diameter of 450mm as an example for analysis.

The main shaft forging blank drawing is shown in figure 1, and the size of an electroslag ingot, forging equipment and tools, a forging deformation mode and the like are determined according to a DIN1.4122 main shaft forging drawing. The process route is as follows: electric furnace smelting and vacuum refining → electroslag remelting → drawing of 5000 ton oil press → forging and forming of fine forging machine → annealing → straightening → physical and chemical detection, inspection → rough machining → thermal refining treatment → physical and chemical detection, inspection → packaging → delivery. The material used is DIN1.4122 steel, and the electroslag ingot is produced by the company.

The specific production flow is as follows: electric furnace smelting + vacuum refining → electroslag remelting → heating → drawing of 5000 ton oil press → fine forging forming → post-forging annealing → straightening → surface inspection, blanking, physical and chemical detection (annealed structure, delta-ferrite content, ultrasonic detection) → rough machining → thermal refining treatment → physical and chemical detection (grain size, non-metal inclusion, mechanical properties (one drawing and three punching), ultrasonic detection), inspection, blanking → ultrasonic detection, size inspection → delivery.

Selecting a phi 1100mm crystallizer and 16.3 tons of electroslag ingots for forging production; and a special heating mode before forging is adopted, the pass deformation and the deformation temperature in the forging process are controlled, and the air cooling temperature control forging production is carried out by utilizing the forging clearance of the oil press rotary precision forging machine. The method effectively avoids the structure stress, controls the internal structure of the forge piece, avoids forging cracking, improves the forging production efficiency, reduces the production cost and has stable product quality.

A forging method of a martensitic stainless steel main shaft comprises the following specific steps:

step 1), selecting materials and making steel by adopting an electric furnace smelting and vacuum refining mode, stirring argon in the whole refining process and pouring under the protection of argon; the internal control chemical components in the refining process are calculated according to the weight percentage: 0.33 to 0.43 percent of C, 15.00 to 17.50 percent of Cr, 0.80 to 1.30 percent of Mo, less than or equal to 1.00 percent of Mn, less than or equal to 1.00 percent of Ni, less than or equal to 1.00 percent of Si, less than or equal to 0.040 percent of P, and less than or equal to 0.015 percent of S; after degassing, on-line hydrogen determination and oxygen determination are carried out, the content of [ H ] is controlled to be less than or equal to 1.5ppm, the content of [ O ] is controlled to be less than or equal to 5ppm, and the content of nitrogen in a gas sample is analyzed to be less than or equal to 90 ppm. High-quality scrap steel is selected as a material, 0.5-1.5 tons of carburant and 0.5-1.5 tons of lime are added into the furnace in advance before feeding, the [ P ] is reduced to be below 0.005 percent by utilizing the advantage of low temperature of molten steel in the early stage of oxidation, and steel retaining and slag retaining operation is adopted for tapping; the vacuum degassing is sufficient, the holding time is more than or equal to 20 minutes under the condition that the pressure is less than or equal to 0.7mbar, and the gas and the nonmetallic inclusion in the molten steel are removed to the maximum extent.

Step 2), remelting the cast martensitic stainless steel spindle electroslag ingot, placing the remelted martensitic stainless steel spindle electroslag ingot in a furnace at 650 +/-10 ℃ for heat preservation for 4 hours, then, quickly heating the ingot in the furnace to the forging temperature of 1200 +/-10 ℃ after the furnace is rotated to perform heat preservation at 800-850 ℃ for 3 hours;

step 3), feeding the martensitic stainless steel spindle electroslag ingot heated to the forging temperature into a 5000-ton oil press for drawing, and controlling the deformation of the main deformation pass of the oil press to be 80-150 mm; hammering the same position once in the deformation process of each pass, performing pull forging on the next position after pressing the hammer once at the same position in the deformation process, after the pass forging of the whole forge piece is finished, starting next pass forging from the other end, forging in a pull forging or push forging mode, avoiding repeated hammering forging at the same position, causing overhigh local temperature rise of the forge piece, generating delta-ferrite, causing forging cracking and influencing the structure after forging, further reducing the impact power after tempering, and stopping forging after the forging is finished to phi 550mm on an upper flat V anvil and a lower V anvil of an oil press;

and 4) feeding the elongated martensitic stainless steel spindle electroslag ingot into a precision forging machine for forging and forming, and meanwhile, performing air cooling temperature control on the forged piece by utilizing a forging gap formed by rotating the precision forging machine by using an oil press, namely performing air cooling temperature control on the forged piece after the oil press finishes forging, and performing forging forming on the precision forging machine after the surface temperature of the forged piece is air cooled to 870-900 ℃ so as to reduce the core temperature of the forged piece, avoid overhigh temperature rise inside the forged piece in the quick forging process of the precision forging machine to generate delta-ferrite, successfully avoid forging in a two-phase region, reduce forging cracking and improve the impact power value after quenching and tempering.

In the process, firstly, the remelting electroslag ingot is placed in an electric furnace at 650 +/-10 ℃ for heat preservation for 4 hours, then a heating furnace is rotated to carry out heat preservation at 800-850 ℃ for 3 hours, and then the temperature is directly raised to the forging temperature for heat preservation, and the electroslag ingot is taken out of the furnace for forging. Therefore, the structural stress generated by heating the cold and cold ingots in the furnace of the electroslag ingot is avoided, the risk of cracking of the electroslag ingot and forging is greatly reduced, the economic cost and the time cost of heating production before forging are saved, and the production efficiency is improved. The special heating specification before forging is shown in figure 2.

The forging process is mainly characterized in that high-temperature delta-ferrite is prevented from being generated in the forging, so that the deformation amount and the deformation speed of each pass are strictly controlled, and the main deformation temperature is controlled to be 930-1150 ℃. In order to avoid the temperature rise inside the forging caused by forging deformation, delta-ferrite is generated inside the forging: controlling the deformation of the main deformation pass of the oil press to be 80-150 mm, and performing single hammering at the same position in the deformation process of each pass, namely performing single hammering at the same position in the deformation process, and performing pull forging at the next position; and after the forging of the whole forging piece in the first pass is finished, starting the forging of the next pass from the other end. The forging method avoids forging cracking and influence on the structure after forging caused by over-high local temperature rise of the forged piece and delta-ferrite generated by multiple times of hammer forging at the same position, and further reduces the impact energy after tempering. And (5) stopping forging after the upper flat anvil and the lower V anvil of the oil press are forged to phi 550mm, and turning to a precision forging machine for forging.

The forging clearance of the oil press rotating precision forging machine is utilized, before the precision forging machine is used for forging, the air cooling temperature control is carried out on the intermediate blank of the DIN1.4122 main shaft forging piece, the core temperature of the forging piece is reduced, and the phenomenon that delta-ferrite is generated due to overhigh temperature inside the forging piece in the rapid forging process of the precision forging machine is avoided, so that the forging in a two-phase region is successfully avoided, the forging cracking is reduced, and the impact power value after quenching and tempering is improved; meanwhile, the method has high efficiency and small forging allowance, and greatly reduces the production cost.

By adopting the special forging method and strictly controlling the forging parameters in each process, the generation of tissue stress and delta-ferrite is avoided, the problem of cracking in the process of forging the DIN1.4122 main shaft forge piece is solved, the impact energy after quenching and tempering is greatly improved, the forging allowance is greatly reduced, the one-time qualified rate of the product is greatly improved, and the production period and the production cost are further reduced.

The results of physicochemical measurements obtained by the above-described strict control of the respective steps are shown in Table 1.

Table 1 test results of examples

Claims (1)

1. A forging method of a martensitic stainless steel main shaft is characterized by comprising the following specific steps:

step 1), selecting materials and making steel by adopting an electric furnace smelting and vacuum refining mode, stirring argon in the whole refining process and pouring under the protection of argon; the internal control chemical components in the refining process are calculated according to the weight percentage: c =0.33% -0.43%, Cr =15.00% -17.50%, Mo =0.80% -1.30%, Mn is less than or equal to 1.00%, Ni is less than or equal to 1.00%, Si is less than or equal to 1.00%, P is less than or equal to 0.040%, and S is less than or equal to 0.015%; after degassing, on-line hydrogen determination and oxygen determination are carried out, the content of [ H ] is controlled to be less than or equal to 1.5ppm, the content of [ O ] is controlled to be less than or equal to 5ppm, and the content of nitrogen in a gas sample is analyzed to be less than or equal to 90 ppm;

high-quality scrap steel is selected as a material, 0.5-1.5 tons of carburant and 0.5-1.5 tons of lime are added into the furnace in advance before feeding, the [ P ] is reduced to be below 0.005 percent by utilizing the advantage of low temperature of molten steel in the early stage of oxidation, and steel retaining and slag retaining operation is adopted for tapping; the vacuum degassing is sufficient, the holding time is more than or equal to 20 minutes under the condition that the gas is less than or equal to 0.7mbar, and the gas and the nonmetallic inclusion in the molten steel are removed to the maximum extent;

step 2), remelting the cast martensitic stainless steel spindle electroslag ingot, placing the remelted martensitic stainless steel spindle electroslag ingot in a furnace at 650 +/-10 ℃ for heat preservation for 4 hours, then, quickly heating the ingot in the furnace to the forging temperature of 1200 +/-10 ℃ after the furnace is rotated to perform heat preservation at 800-850 ℃ for 3 hours;

step 3), feeding the martensitic stainless steel spindle electroslag ingot heated to the forging temperature into a 5000-ton oil press for drawing, and controlling the deformation of the main deformation pass of the oil press to be 80-150 mm; hammering the same position once in the deformation process of each pass, performing pull forging on the next position after pressing the hammer once at the same position in the deformation process, after the pass forging of the whole forge piece is finished, starting next pass forging from the other end, forging in a pull forging or push forging mode, avoiding repeated hammering forging at the same position, causing overhigh local temperature rise of the forge piece, generating delta-ferrite, causing forging cracking and influencing the structure after forging, further reducing the impact power after tempering, and stopping forging after the forging is finished to phi 550mm on an upper flat V anvil and a lower V anvil of an oil press;

and 4) feeding the elongated martensitic stainless steel spindle electroslag ingot into a precision forging machine for forging and forming, and meanwhile, performing air cooling temperature control on the forged piece by utilizing a forging gap formed by rotating the precision forging machine by using an oil press, namely performing air cooling temperature control on the forged piece after the oil press finishes forging, and performing forging forming on the precision forging machine after the surface temperature of the forged piece is air cooled to 870-900 ℃ so as to reduce the core temperature of the forged piece, avoid overhigh temperature rise inside the forged piece in the quick forging process of the precision forging machine to generate delta-ferrite, successfully avoid forging in a two-phase region, reduce forging cracking and improve the impact power value after quenching and tempering.

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