CN115125444A - Q550ME thick-wall free forging and hot working method for improving mechanical property thereof - Google Patents

Q550ME thick-wall free forging and hot working method for improving mechanical property thereof Download PDF

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CN115125444A
CN115125444A CN202210733215.9A CN202210733215A CN115125444A CN 115125444 A CN115125444 A CN 115125444A CN 202210733215 A CN202210733215 A CN 202210733215A CN 115125444 A CN115125444 A CN 115125444A
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temperature
forging
q550me
thick
mechanical property
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CN115125444B (en
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杜巧林
阮宜江
张煌
谭启海
王仁江
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Chongqing Xinchenghangrui Technology Co ltd
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Chongqing Xinchenghangrui Technology Co ltd
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
    • B21J1/00—Preparing metal stock or similar ancillary operations prior, during or post forging, e.g. heating or cooling
    • B21J1/06—Heating or cooling methods or arrangements specially adapted for performing forging or pressing operations
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
    • B21J5/00—Methods for forging, hammering, or pressing; Special equipment or accessories therefor
    • B21J5/002—Hybrid process, e.g. forging following casting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21K—MAKING FORGED OR PRESSED METAL PRODUCTS, e.g. HORSE-SHOES, RIVETS, BOLTS OR WHEELS
    • B21K29/00—Arrangements for heating or cooling during processing
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/004—Heat treatment of ferrous alloys containing Cr and Ni
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/005—Heat treatment of ferrous alloys containing Mn
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/008—Heat treatment of ferrous alloys containing Si
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/005—Modifying the physical properties by deformation combined with, or followed by, heat treatment of ferrous alloys
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/54—Ferrous alloys, e.g. steel alloys containing chromium with nickel with boron
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/002—Bainite
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/005—Ferrite
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

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  • Physics & Mathematics (AREA)
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  • Crystallography & Structural Chemistry (AREA)
  • Forging (AREA)

Abstract

The invention provides a Q550ME thick-wall free forging and a hot working method for improving the mechanical property thereof, which comprises the steps of pretreating raw materials, putting the pretreated raw materials into a high-temperature furnace for low-temperature heating, then carrying out 1-pass forming temperature-controlled forging on a two-phase region of materials Ac3-Ac1, immediately carrying out rapid cooling to room temperature after forging, and then carrying out high-temperature tempering to obtain a product; the low-temperature heating condition is that the temperature is kept at 600 ℃ for 1h, then the temperature is raised to 850 ℃ and kept for 2 h; the high-temperature tempering temperature is 540-. The invention meets the product performance requirement of the wall thickness within the range of 100-200mm by adopting the hot processing method of controlling components, temperature, shape and cooling for the free forging.

Description

Q550ME thick-wall free forging and hot working method for improving mechanical property thereof
Technical Field
The invention is applied to the technical field of Q550ME forgings, and particularly relates to a Q550ME thick-wall free forging and a hot working method for improving the mechanical property of the free forging.
Background
The Q550ME belongs to low-carbon high-strength alloy structural steel, and the material is widely used for steel plates, flat steels, section steels and bar materials used for ship bodies, machinery, boilers, pressurized containers, ocean engineering and the like, and the performance of forgings is generally supplied in the forms of hot rolled steel plates, steel bars and the like according to the standard GB/T1591-2018. As mechanical equipment products are larger and larger at present, required part products are larger and larger, the wall thickness of many parts exceeds the wall thickness dimension of the products specified in GB/T1591-2018, and after the parts are treated by conventional processes such as hot rolling and the like, the performance requirements of the products cannot be met due to factors such as the depth of a hardening layer, hardenability, sampling positions and the like.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a Q550ME thick-wall free forging and a hot processing method for improving the mechanical property thereof, and the product performance requirement of the wall thickness within the range of 100-200mm is met by adopting a hot processing method of controlling components, temperature, shape and cooling for the free forging.
The technical problem to be solved by the invention is realized by adopting the following technical scheme:
the invention aims to provide a Q550ME thick-wall free forging, which is characterized by comprising the following chemical components in percentage by weight: c: 0.12-0.18%, Si: 0.4-0.6%, Mn: 0.9-1.5%, Cr: 0.3-0.6%, Ni: 0.15-0.5%, Mo: 0.1-0.2%, Cu: not more than 0.4%, P not more than 0.02%, S not more than 0.015%, Als: not less than 0.015%, B not more than 0.004%, N: less than or equal to 0.025 percent, Nb: 0.01-0.11%, Ti: 0.006-0.05%, V: 0.01-0.12%, CEV: less than or equal to 0.47 percent, and the balance of iron and inevitable impurities.
Further, Rm is larger than 670MPa and Rp0.2 is larger than 550MPa when the thickness of the Q550ME forging is 100-200 mm.
The second purpose of the invention is to provide a hot working method for improving the mechanical property of a Q550ME thick-wall free forged piece, which is characterized in that the method comprises the steps of pretreating raw materials, placing the pretreated raw materials into a high-temperature furnace for low-temperature heating, then carrying out 1-time forming temperature-controlled forging in a two-phase region of materials Ac3-Ac1, immediately carrying out rapid cooling to room temperature after forging, and then carrying out high-temperature tempering to obtain a product; the low-temperature heating condition is that the temperature is kept at 600 ℃ for 1h, then the temperature is raised to 850 ℃ and kept for 2 h; the high-temperature tempering temperature is 540-.
Furthermore, the raw material pretreatment means that the raw material is put into a high-temperature furnace for heating before forging, and then is subjected to the fire forming and cogging treatment on an oil press 1.
Further, the heating before forging refers to charging the raw materials in a high-temperature furnace when the temperature is kept at 600 ℃, and preserving the heat for 1-2.5 hours at 600 ℃; then heating to 800-900 ℃ and preserving the heat for 1-2.5 hours; then heating to 1200-1260 ℃, and preserving the temperature for 4-6 hours.
Furthermore, the temperature conditions of heating before forging are selected from 600 ℃ for 2h, 850 ℃ for 2h and 1250 ℃ for 4.5 h.
Furthermore, the cogging treatment is carried out by upsetting and then drawing, and the upsetting ratio is more than or equal to 2.0.
Further, the forging tool is preheated to the temperature of 200-300 ℃ before the temperature-controlled forging, and then the forging is started. The forging tool is preheated firstly, and the contact heat transfer loss of the blank and the tool auxiliary tool is reduced.
Furthermore, the temperature-controlled forging process comprises the steps of drawing out a blank from a furnace according to the metal streamline direction, rounding, upsetting, rounding, punching, shaping in the height direction and finally shaping to obtain a forging.
Furthermore, the total forging ratio in the temperature-controlled forging process is 4.3, the upsetting deformation is more than or equal to 50 percent, and the whole temperature-controlled forging process is controlled within 5-7 minutes. The forging time is greatly shortened, the production period is prolonged, the production efficiency is improved, the consumption of a large amount of energy is saved, and the production cost is saved.
Further, the temperature-controlled forging temperature range is 750-850 ℃.
A hot working method for improving the mechanical property of a Q550ME thick-wall free forging comprises the following steps:
1) heating before forging. Charging the qualified raw materials in a high-temperature furnace when the temperature is kept at 600 ℃, and preserving the heat at 600 ℃ for 1-2.5 hours; then heating to 800-900 ℃ and preserving the heat for 1-2.5 hours; then heating to 1200-1260 ℃, and preserving the temperature for 4-6 hours.
2) And (5) cogging treatment. The heated raw materials are subjected to 1-fire forming cogging treatment on a 2500T oil press, upsetting is firstly carried out, the upsetting ratio is more than or equal to 2.0, and then drawing is carried out.
3) And (5) blanking by a sawing machine. And (4) blanking the cogging-treated raw materials by a sawing machine according to the required processing size through calculation to obtain a blank with the required size.
4) And (4) heating at a low temperature. Keeping the temperature at 600 ℃ for 1h, then heating to 850 ℃ and keeping the temperature for 2 h.
5) And (5) controlling the temperature and forging. Preheating the forging tool to the temperature of 200 ℃ and 300 ℃ before temperature-controlled forging, and controlling the time from discharging to forging starting of the blank within 30 seconds; firstly, pressing a discharged blank on a 7T electro-hydraulic hammer in a metal streamline direction to perform square drawing and rounding, and controlling the time within 2 minutes; and then upsetting, rounding, punching, shaping in the height direction, and finally shaping to obtain the forged piece, wherein the time is controlled within 3-4 minutes. The temperature-controlled forging temperature range is 750-850 ℃, the total forging ratio in the temperature-controlled forging process is 4.3, the upsetting deformation is more than or equal to 50 percent, and the whole temperature-controlled forging process is controlled within 5-7 minutes.
6) And (5) cooling quickly. And (4) quickly putting the forged piece subjected to temperature control forging into cold water to be quickly cooled to room temperature.
7) And (4) high-temperature tempering. And (3) tempering the forging which is rapidly cooled to room temperature in an electric furnace, wherein the high-temperature tempering temperature is 540 and 560 ℃, and the temperature is kept for 8 h.
8) And detecting the forged piece after high-temperature tempering.
Compared with the prior art, the invention has the beneficial effects that:
the invention adjusts the heating temperature of the forming heat and the cooling after forging and the like by adjusting the chemical components in the raw materials and improving the process, cancels the quenching and tempering treatment in the prior art, and improves the performance indexes of the material such as hardenability, low-temperature impact energy, refined grain size and the like. According to the invention, temperature-controlled large-deformation forging is carried out in a low-temperature Ac3-Ac1 two-phase region, and then ferrite and bainite tissues are obtained by rapid cooling, so that the grain size refinement and work hardening are achieved. After high-temperature tempering is matched, the product meets the final performance requirement of customers. The invention can meet the condition that Rm is more than 670MPa and Rp0.2 is more than 550MPa when the thickness is 100-200 mm. The invention has short production period, saves a large amount of energy consumption, improves the production efficiency, and has simple process and easy operation.
Drawings
FIG. 1 is a processing flow chart of the prior art in a Q550ME thick-wall free forging and a hot working method for improving mechanical properties thereof.
FIG. 2 is a processing flow chart of the Q550ME thick-wall free forging and the hot working method for improving the mechanical property of the thick-wall free forging.
FIG. 3 is a temperature change curve of heating before forging in the Q550ME thick-wall free forging and the hot working method for improving the mechanical property thereof.
FIG. 4 is a cross-sectional view of a cogging treatment in the Q550ME thick-wall free forging and the hot working method for improving the mechanical property of the thick-wall free forging.
Fig. 5 is a temperature change curve of low-temperature heating in the Q550ME thick-wall free forging and the hot working method for improving the mechanical property thereof.
FIG. 6 is a sectional view of the temperature controlled forging in the Q550ME thick-wall free forging and the hot working method for improving the mechanical property thereof.
FIG. 7 is a temperature change curve of high-temperature tempering in the Q550ME thick-wall free forging and the hot working method for improving the mechanical property thereof.
FIG. 8 is a metallographic microstructure diagram of a forged product in the Q550ME thick-wall free forging and the hot working method for improving the mechanical property of the forged product.
Detailed Description
The technical solution of the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. It is to be understood that the following examples are only illustrative and explanatory of the present invention and should not be construed as limiting the scope of the present invention. All the technologies realized based on the above-mentioned contents of the present invention are covered in the protection scope of the present invention.
The forgings selected by the invention are all in the range of wall thickness 100-.
Example 1:
a Q550ME thick-wall free forging comprises the following chemical components in percentage by weight: c: 0.13%, Si: 0.5%, Mn: 1.05%, Cr: 0.35%, Ni: 0.47%, Mo: 0.15%, Cu: 0.25%, P0.012%, S0.009%, Als: 0.035%, B0.002%, N0.009%, Nb: 0.05%, Ti: 0.02%, V: 0.08%, CEV: 0.47%, the balance being iron and unavoidable impurities.
A hot working method for improving the mechanical property of a Q550ME thick-wall free forging comprises the following steps:
1) heating before forging. Charging the qualified raw materials in a high-temperature furnace when the temperature is kept at 600 ℃, and preserving the heat for 2 hours at 600 ℃; then heating to 850 ℃ and preserving the heat for 2 hours; then the temperature is raised to 1250 ℃ and the temperature is preserved for 4.5 hours.
2) And (5) cogging treatment. The heated raw materials are subjected to 1-fire forming cogging treatment on a 2500T oil press, upsetting is firstly carried out, the upsetting ratio is more than or equal to 2.0, and then drawing is carried out.
3) And (5) blanking by a sawing machine. And (4) blanking the cogging-treated raw materials by a sawing machine according to the required processing size through calculation to obtain a blank with the required size.
4) And (4) heating at a low temperature. Keeping the temperature at 600 ℃ for 1h, heating to 850 ℃ and keeping the temperature for 2 h.
5) And (5) controlling the temperature and forging. Preheating a forging tool to 250 ℃ before temperature-controlled forging, and controlling the time from discharging to forging starting of a blank within 30 seconds; firstly, pressing a discharged blank on a 7T electro-hydraulic hammer in a metal streamline direction to perform square drawing and rounding, and controlling the time within 2 minutes; and then upsetting, rounding, punching, shaping in the height direction, and finally shaping to obtain the forged piece, wherein the time is controlled within 3-4 minutes. The temperature-controlled forging temperature range is 750-850 ℃, the total forging ratio in the temperature-controlled forging process is 4.3, the upsetting deformation is more than or equal to 50 percent, and the whole temperature-controlled forging process is controlled within 5-7 minutes.
6) And (6) rapidly cooling. And (4) quickly putting the forged piece subjected to temperature control forging into cold water to be quickly cooled to room temperature.
7) And (4) high-temperature tempering. And (3) tempering the forge piece which is quickly cooled to room temperature in an electric furnace, wherein the high-temperature tempering temperature is 550 ℃, and the temperature is kept for 8 hours.
8) And detecting the forged piece after high-temperature tempering.
Example 2:
a Q550ME thick-wall free forging comprises the following chemical components in percentage by weight: c: 0.122%, Si: 0.6%, Mn: 0.9%, Cr: 0.4%, Ni: 0.45%, Mo: 0.12%, Cu: 0.2%, P: 0.01%, S: 0.005%, Als: 0.05%, B: 0.004%, N: 0.015%, Nb: 0.11%, Ti: 0.006%, V: 0.10%, CEV: 0.44%, the balance being iron and unavoidable impurities.
The working-up procedure was carried out as in example 1.
Example 3:
a Q550ME thick-wall free forging comprises the following chemical components in percentage by weight: c: 0.132%, Si: 0.4%, Mn: 1.15%, Cr: 0.3%, Ni: 0.5%, Mo: 0.1%, Cu: 0.4%, P: 0.015%, S: 0.01%, Als: 0.3%, B: 0.001%, N: 0.02%, Nb: 0.01%, Ti: 0.05%, V: 0.04%, CEV: 0.47%, the balance being iron and unavoidable impurities.
The working-up procedure was carried out as in example 1.
Comparative example 1:
a Q550ME thick-wall free forging comprises the following chemical components in percentage by weight: c: 0.144%, Si: 0.35%, Mn: 1.28%, Cr: 0.13%, Ni: 0.22%, Mo: 0.005%, Cu: 0.44%, P: 0.012%, S: 0.018%, Als: 0.025%, B: 0.002%, N: 0.025%, Nb: 0.05%, Ti: 0.02%, V: 0.08%, CEV: 0.44 percent.
The hot working method of the thick-wall free forging of the comparative example Q550ME comprises the following steps:
1) heating before forging. Charging the qualified raw materials in a high-temperature furnace when the temperature is kept at 600 ℃, and preserving the heat for 2 hours at 600 ℃; then heating to 850 ℃ and preserving the heat for 2 hours; then the temperature is raised to 1250 ℃ and the temperature is preserved for 4.5 hours.
2) And (5) cogging treatment. And (3) performing 1-fire forming cogging treatment on the heated raw materials on a 2500T oil press, firstly performing upsetting, wherein the upsetting ratio is more than or equal to 2.0, and then drawing.
3) And (5) blanking by a sawing machine. And (4) blanking the cogging-treated raw materials by a sawing machine according to the required processing size through calculation to obtain a blank with the required size.
4) Heating at high temperature. The blank is placed in a high-temperature furnace when the temperature is kept at 600 ℃, and the temperature is raised to 850 ℃ and kept for 1 hour; then the temperature is increased to 1220 ℃ and the temperature is preserved for 2 hours.
5) And (5) forging. Preheating a forging tool to 250 ℃ before forging, pressing a discharged blank on a 7T electro-hydraulic hammer in a metal streamline direction, drawing out the blank in a square way, and rounding; then upsetting, rounding, punching and shaping in the height direction, and finally shaping to obtain the forged piece, wherein the finish forging temperature of the forged piece is controlled at 800 ℃.
6) And air cooling after forging. And air cooling the forged piece after high-temperature forging to room temperature.
7) And (6) quenching and tempering. And heating the air-cooled forge piece to 650 ℃ in an electric furnace, preserving heat for 1h, heating to 920 ℃ and preserving heat for 4h, then cooling by water, and tempering the forge piece cooled to room temperature by water in the electric furnace, wherein the high-temperature tempering temperature is 550 ℃ and the heat is preserved for 6 h.
8) And detecting the forged piece after quenching and tempering.
Comparative example 2:
a Q550ME thick-wall free forging comprises the following chemical components in percentage by weight: c: 0.144%, Si: 0.35%, Mn: 1.28%, Cr: 0.13%, Ni: 0.22%, Mo: 0.005%, Cu: 0.44%, P: 0.012%, S: 0.018%, Als: 0.025%, B: 0.002%, N: 0.025%, Nb: 0.05%, Ti: 0.02%, V: 0.08%, CEV: 0.44 percent.
The hot working method of the thick-wall free forging of the comparative example Q550ME comprises the following steps:
1) heating before forging. Charging the qualified raw materials in a high-temperature furnace when the temperature is kept at 600 ℃, and preserving the heat for 2 hours at 600 ℃; then heating to 850 ℃ and preserving the heat for 2 hours; then the temperature is raised to 1250 ℃ and the temperature is preserved for 4.5 hours.
2) And (5) cogging treatment. And (3) performing 1-fire forming cogging treatment on the heated raw materials on a 2500T oil press, firstly performing upsetting, wherein the upsetting ratio is more than or equal to 2.0, and then drawing.
3) And (6) blanking by a sawing machine. And (4) blanking the cogging-treated raw materials by a sawing machine according to the required processing size through calculation to obtain a blank with the required size.
4) And (4) heating at a low temperature. Keeping the temperature at 600 ℃ for 1h, then heating to 850 ℃ and keeping the temperature for 2 h.
5) And (5) controlling the temperature and forging. Preheating a forging tool to 250 ℃ before temperature-controlled forging, and controlling the time from discharging to forging starting of a blank within 30 seconds; firstly, pressing a discharged blank on a 7T electro-hydraulic hammer in a metal streamline direction to perform square drawing and rounding, and controlling the time within 2 minutes; and then upsetting, rounding, punching, shaping in the height direction, and finally shaping to obtain the forged piece, wherein the time is controlled within 3-4 minutes. The temperature-controlled forging temperature range is 750-850 ℃, the total forging ratio in the temperature-controlled forging process is 4.3, the upsetting deformation is more than or equal to 50 percent, and the whole temperature-controlled forging process is controlled within 5-7 minutes.
6) And (6) rapidly cooling. And (4) quickly putting the forged piece subjected to temperature control forging into cold water to be quickly cooled to room temperature.
7) And (4) high-temperature tempering. And (3) tempering the forge piece which is rapidly cooled to room temperature in an electric furnace, wherein the high-temperature tempering temperature is 550 ℃, and the temperature is kept for 8 hours.
8) And detecting the forged piece after high-temperature tempering.
The forged pieces tempered in the examples and the comparative examples are detected, and the detection results are shown in table 1. It can be seen that, compared with the technical scheme of the invention, the forging obtained by the comparative example 1 according to the original process and chemical composition is far from the standard requirements in tensile strength and yield strength, and the later stage can not meet the standard requirements only for any improvement of the chemical composition and the forging process in the prior art. Comparative example 2 the forging process was improved and forging was performed according to the method of the present invention, but the tensile strength and yield strength of the forged part could not meet the standard requirements no matter how adjusted on the prior art before improvement. The invention improves the chemical components of the raw materials, the heating temperature of the forming fire, high-temperature tempering, cooling after forging and the like, and improves the performance indexes of hardenability, low-temperature impact energy, refined grain size and the like of the material. By adjusting the raw material composition of Si, Mo, Cu and the like and strictly limiting the composition interval of components of C, Si, Mn, Cr, Ni, Mo and the like, the performance indexes of hardenability, low-temperature impact energy, refined grain size and the like of the material are improved, and the obtained forged piece meets the performance requirements of standards. The forging temperature interval is selected to carry out temperature-controlled large-deformation forging between two phase regions of Ac3-Ac1, and then the temperature-controlled large-deformation forging is rapidly cooled to obtain a ferrite and bainite structure, so that the refined grain size and the work hardening are achieved, see attached figure 8, and the improved forging piece has small grain size and compact material.
TABLE 1
Figure BDA0003714680140000071
The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above-described embodiments. It will be understood by those skilled in the art that various changes, substitutions of equivalents, and alterations can be made without departing from the spirit and scope of the invention.

Claims (10)

1. A Q550ME thick-wall free forging is characterized by comprising the following chemical components in percentage by weight: c: 0.12-0.18%, Si: 0.4-0.6%, Mn: 0.9-1.5%, Cr: 0.3-0.6%, Ni: 0.15-0.5%, Mo: 0.1-0.2%, Cu: not more than 0.4%, P not more than 0.02%, S not more than 0.015%, Als: not less than 0.015%, B not more than 0.004%, N: less than or equal to 0.025%, Nb: 0.01-0.11%, Ti: 0.006-0.05%, V: 0.01-0.12%, CEV: less than or equal to 0.47 percent, and the balance of iron and inevitable impurities.
2. A Q550ME thick-walled free forging of claim 1, wherein: rm of the Q550ME forging is larger than 670MPa when the thickness is 100-200mm, and Rp0.2 is larger than 550 MPa.
3. A hot working method for improving the mechanical property of the Q550ME thick-wall free forging piece of claim 1 or 2, wherein the method comprises the following steps: the method comprises the following steps of (1) pretreating raw materials, placing the pretreated raw materials into a high-temperature furnace for low-temperature heating, then performing 1-time forming temperature-controlled forging in a two-phase region of materials Ac3-Ac1, immediately performing rapid cooling to room temperature after forging, and then performing high-temperature tempering to obtain a product; the low-temperature heating condition is that the temperature is kept at 600 ℃ for 1h, then the temperature is raised to 850 ℃ and kept for 2 h; the high-temperature tempering temperature is 540-560 ℃ and the temperature is kept for 8 h.
4. The hot working method for improving the mechanical property of the Q550ME thick-wall free forging as claimed in claim 3, wherein: the raw material pretreatment means that the raw material is put into a high-temperature furnace for heating before forging, and then is subjected to fire forming and cogging treatment on an oil press 1.
5. The hot working method for improving the mechanical property of the Q550ME thick-wall free forging as claimed in claim 3, wherein: the heating before forging refers to charging the raw materials in a high-temperature furnace when the temperature is kept at 600 ℃, and preserving the heat for 1-2.5 hours at 600 ℃; then heating to 800-900 ℃ and preserving the heat for 1-2.5 hours; then heating to 1200-1260 ℃, and preserving the temperature for 4-6 hours.
6. The hot working method for improving the mechanical property of the Q550ME thick-wall free forging as claimed in claim 5, wherein: the temperature conditions of heating before forging are selected from 600 ℃ for 2h, 850 ℃ for 2h and 1250 ℃ for 4.5 h.
7. The hot working method for improving the mechanical property of the Q550ME thick-wall free forging as claimed in claim 3, wherein: and upsetting and then drawing out during cogging treatment, wherein the upsetting ratio is more than or equal to 2.0.
8. The hot working method for improving the mechanical property of the Q550ME thick-wall free forged piece as claimed in claim 3, wherein: the temperature control forging process comprises the steps of drawing out a discharged blank in four directions according to the metal streamline direction, rounding, upsetting in the height direction, rounding, punching, shaping and finally shaping to obtain a forging piece.
9. The hot working method for improving the mechanical property of the Q550ME thick-wall free forged piece as claimed in claim 8, wherein: the total forging ratio in the temperature-controlled forging process is 4.3, the upsetting deformation is more than or equal to 50 percent, and the whole temperature-controlled forging process is controlled within 5-7 minutes. The forging time is greatly shortened, the production period is prolonged, the production efficiency is improved, the consumption of a large amount of energy is saved, and the production cost is saved.
10. The hot working method for improving the mechanical property of the Q550ME thick-wall free forging as claimed in claim 9, wherein: the temperature control forging temperature range is 750-850 ℃.
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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111304545A (en) * 2019-12-09 2020-06-19 无锡市法兰锻造有限公司 Low-temperature steel forging produced by using continuous casting billet and manufacturing method thereof
CN113088790A (en) * 2021-03-22 2021-07-09 无锡继平锻造有限公司 C-Mn high-strength steel forging and heat treatment process for welded structural part

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111304545A (en) * 2019-12-09 2020-06-19 无锡市法兰锻造有限公司 Low-temperature steel forging produced by using continuous casting billet and manufacturing method thereof
CN113088790A (en) * 2021-03-22 2021-07-09 无锡继平锻造有限公司 C-Mn high-strength steel forging and heat treatment process for welded structural part

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