CN114657363A - Method for improving 42CrMoA crankshaft band-shaped structure - Google Patents
Method for improving 42CrMoA crankshaft band-shaped structure Download PDFInfo
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- CN114657363A CN114657363A CN202210186512.6A CN202210186512A CN114657363A CN 114657363 A CN114657363 A CN 114657363A CN 202210186512 A CN202210186512 A CN 202210186512A CN 114657363 A CN114657363 A CN 114657363A
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- 42crmoa
- crankshaft
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- 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
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/30—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for crankshafts; for camshafts
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- 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
-
- 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
-
- 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
-
- 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
- C22C38/18—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
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Forging (AREA)
- Heat Treatment Of Articles (AREA)
- Shafts, Cranks, Connecting Bars, And Related Bearings (AREA)
Abstract
The invention relates to a method for improving 42CrMoA crankshaft banded structure, which comprises the following steps: the method comprises the steps of cogging and forging a hot steel ingot through an oil press to prepare an intermediate billet, returning the intermediate billet to a furnace for heating at 1230-1270 ℃ for 10-20 h, after heat preservation, pulling out a material airing to 600-650 ℃ by a trolley, reducing the furnace temperature to 930-970 ℃, returning the furnace for heat preservation for 2h, taking out the material airing to 750-800 ℃ for fine forging machine forging and forming, after forging, quickly cooling a forged piece to 350-400 ℃, heating the forged piece to 600-650 ℃ at full power, preserving heat for 1h/100mm, heating the forged piece to 840-880 ℃ at full power, preserving heat for 1-2 h/100mm, quickly cooling the forged piece to 400-450 ℃, heating the forged piece to 630-670 ℃ at full power, preserving heat for 4h/100mm, and cooling the forged piece to be less than or equal to 30 ℃/h for less than or equal to 450 ℃ after heat preservation.
Description
Technical Field
The invention belongs to the technical field of crankshaft manufacturing processes, and particularly relates to a method for improving a 42CrMoA crankshaft band-shaped structure.
Background
When the steel ingot is subjected to hot press working, two kinds of structures may be alternately layered in the rolling direction, and such a structure as seen under a microscope is called a band-shaped structure. After low-carbon steel, medium-carbon steel and low-alloy structural steel are subjected to press working, a banded structure with alternately-layered ferrite and pearlite tends to appear; in the high carbon alloy steel, a band-shaped structure of carbide occurs. The strip structure is the main cause of anisotropy of steel, and obviously reduces the transverse plasticity and toughness of steel. When the band-shaped structure is severe, the machinability of the steel is impaired, the finish of the machined surface is poor, the carburized layer tends to be uneven during carburization, and the steel tends to be deformed during heat treatment and has uneven hardness. Therefore, the forging with high requirements has certain limit requirements on the level of the band-shaped structure.
The 42CrMoA crankshaft has high requirements on anisotropy and structural uniformity of materials, has strict requirements on a band-shaped structure, generally requires that the level of the band-shaped structure is less than or equal to 2.0, most of the levels of the band-shaped structures produced by the general process are about 3.0, the production rework rate is high, and the production difficulty is high.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide a method for improving the band-shaped structure of a 42CrMoA crankshaft, which solves the problem of unqualified band-shaped structure aiming at the band-shaped structure cause.
The technical scheme of the invention for achieving the aim is as follows: a method for improving 42CrMoA crankshaft band-shaped tissue comprises the following specific steps:
step 1), cogging and forging the hot-fed steel ingots into intermediate billets through an oil press, then returning the intermediate billets to a furnace for heating 1230-1270 ℃, preserving the heat for 10-20 h, after the heat preservation is finished, pulling out the aired materials by a trolley to 600-650 ℃, reducing the furnace temperature to 930-970 ℃, returning the furnace for heat preservation for 2h, taking out the materials from the furnace, airing the materials to 750-800 ℃, and feeding the materials into a precision forging machine for forging and forming;
step 2), after forging, quickly cooling the forged piece to 350-400 ℃, heating the forged piece to 600-650 ℃ at full power for waiting for material, preserving heat for 1h/100mm, heating the forged piece to 840-880 ℃ at full power, and preserving heat for 1-2 h/100 mm; and after the heat preservation is finished, quickly cooling to 400-450 ℃, then heating to 630-670 ℃ at full power, preserving heat for 4h/100mm, after the heat preservation is finished, cooling to less than or equal to 450 ℃ at a rate of less than or equal to 30 ℃/h, and discharging from the furnace for air cooling.
Preferably, the rapid cooling in the step 2) is air cooling or fog cooling.
Preferably, in the step 1), when the intermediate blank is returned to the furnace for heating, the optimal temperature rise is 1250 +/-10 ℃, and the optimal heat preservation time is 15 h.
Preferably, in the step 2), when the temperature is raised by the full power, the optimal temperature is 860 +/-10 ℃, the optimal heat preservation time is 1.5h/100mm, the temperature is quickly cooled to 400-450 ℃ after the heat preservation is finished, and the temperature is raised to the optimal temperature of 650 +/-10 ℃ by the full power.
The 42CrMoA crankshaft is a vacuum refining die casting forged piece, and the steel for the crankshaft comprises, by mass, 0.38-0.45% of carbon, 0.20-0.40% of silicon, 0.60-0.90% of manganese, 0.30-0.60% of nickel, 0.90-1.20% of chromium, 0.15-0.25% of molybdenum, 0.05-0.12% of vanadium and the balance of iron.
The technical scheme of the invention has the following positive effects:
1. the hot-delivered steel ingots are subjected to cogging forging through an oil press to prepare intermediate billets, then the intermediate billets are returned to a furnace to be heated to 1230-1270 ℃ for heat preservation, and after the heat preservation is finished, the trolley pulls out and dries the materials to 600-650 ℃; the intermediate blank is diffused, so that the component segregation of the steel ingot is reduced or eliminated, the structure is homogenized, and the banded structure is reduced.
2. And after forging, quickly cooling the forging to 350-400 ℃, raising the temperature to 600-650 ℃ at full power for material waiting, preserving heat, raising the temperature to 840-880 ℃ at full power after heat preservation, and preserving heat. And after the heat preservation is finished, quickly cooling to 400-450 ℃, and then heating to 630-670 ℃ at full power. After high-temperature austenitization, the crankshaft forging piece is quickly cooled to a pearlite transformation zone to ensure that ferrite cannot precipitate in time, and then isothermal holding is carried out in the pearlite transformation zone to ensure that different parts of the crankshaft forging piece and the crankshaft forging piece are transformed at the same isothermal temperature, so that a uniform ferrite plus pearlite or pseudo eutectoid structure of pearlite is formed, and the level of a banded structure is further reduced.
Drawings
FIG. 1 is a graph showing an isothermal normalizing process of the steel for 42CrMoA crankshaft of the present invention.
Detailed Description
The technical solution of the present invention is further illustrated by the following specific embodiments, but the scope of the present invention is not limited thereto.
Example 1: a method for improving 42CrMoA crankshaft band-shaped structure is disclosed, the crankshaft specification is phi 290mm multiplied by 5025mm, and the steel for the crankshaft comprises the following chemical components in percentage by mass: c: 0.42%, Si 0.25%, Mn 0.75%, Ni: 0.33%, Cr: 1.13%, Mo: 0.22%, V: 0.08 percent, and the balance of Fe and other inevitable impurities, and adopts a vacuum refining die for ingot casting.
The method comprises the following specific steps:
step 1), cogging and forging a hot-fed steel ingot into an intermediate billet through an oil press, then returning the intermediate billet to a furnace for heating 1250 +/-10 ℃, preserving heat for 15 hours, after heat preservation is finished, pulling out a material airing to 600-650 ℃ by a trolley, reducing the furnace temperature to 950 +/-10 ℃, returning to the furnace for preserving heat for 2 hours, taking out the material from the furnace, airing to 750-800 ℃, and feeding the material into a precision forging machine for forging and forming;
step 2), after forging, air-cooling the forged piece to 350-400 ℃, heating the forged piece to 600-650 ℃ at full power for waiting for material, preserving heat for 3 hours, heating the forged piece to 860 +/-10 ℃ at full power, and preserving heat for 4.5 hours; after the heat preservation is finished, fog cooling is carried out to 400-450 ℃, then the temperature is raised to 650 +/-10 ℃ at full power, the heat preservation is carried out for 11.5h, furnace cooling is carried out to be less than or equal to 450 ℃ at the speed of less than or equal to 30 ℃/h after the heat preservation is finished, and the furnace is taken out and air cooled.
The 42CrMoA crankshaft produced by the process has the following detection results of the strip-shaped structure after forging:
| test No | Sampling site | Banded organization (grade) |
| 1 | 1/2 radius | 0 |
| 2 | 1/2 radius | 1.0 |
Example 2: a method for improving 42CrMoA crankshaft band-shaped structure is disclosed, the crankshaft specification is phi 345mm multiplied by 5495mm, the crankshaft steel comprises the following chemical components by mass percent: c: 0.40%, Si 0.26%, Mn 0.71%, Ni: 0.35%, Cr: 1.13%, Mo: 0.22%, V: 0.09 percent, and the balance of Fe and other inevitable impurities, and adopts a vacuum refining die for ingot casting.
The method comprises the following specific steps:
step 1), cogging and forging a hot-fed steel ingot into an intermediate billet through an oil press, then returning the intermediate billet to a furnace, heating to 1250 +/-10 ℃, preserving heat for 15 hours, after heat preservation, pulling out a material airing to 600-650 ℃ by a trolley, reducing the furnace temperature to 950 +/-10 ℃, returning to the furnace, preserving heat for 2 hours, taking out the material from the furnace, airing to 750-800 ℃, and feeding the material into a precision forging machine for forging and forming;
step 2), after forging, air-cooling the forged piece to 350-400 ℃, heating the forged piece to 600-650 ℃ at full power for waiting for material, preserving heat for 3.5 hours, heating the forged piece to 860 +/-10 ℃ at full power, and preserving heat for 5.5 hours; after the heat preservation is finished, fog cooling is carried out to 400-450 ℃, then the temperature is raised to 650 +/-10 ℃ at full power, the heat preservation is carried out for 14h, furnace cooling is carried out to be less than or equal to 450 ℃ at the speed of less than or equal to 30 ℃/h after the heat preservation is finished, and the furnace is taken out and air cooled.
The 42CrMoA crankshaft produced by the process has the following detection results of the strip-shaped structure after forging:
| test No | Sampling site | Banded organization (grade) |
| 1 | 1/2 radius | 1.0 |
| 2 | 1/2 at radius | 0.5 |
Claims (5)
1. A method for improving 42CrMoA crankshaft band-shaped tissue is characterized in that: the method comprises the following specific steps:
step 1), cogging and forging a hot-fed steel ingot into an intermediate billet through an oil press, then returning the intermediate billet to a furnace for heating 1230-1270 ℃, preserving heat for 10-20 h, after heat preservation, pulling out a material for drying to 600-650 ℃ by a trolley, reducing the furnace temperature to 930-970 ℃, returning to the furnace for preserving heat for 2h, taking out the material for drying to 750-800 ℃, and feeding the material into a precision forging machine for forging and forming;
step 2), after forging, quickly cooling the forged piece to 350-400 ℃, raising the temperature to 600-650 ℃ at full power for material waiting, preserving heat for 1h/100mm, raising the temperature to 840-880 ℃ at full power, and preserving heat for 1-2 h/100 mm; and after the heat preservation is finished, quickly cooling to 400-450 ℃, then heating to 630-670 ℃ at full power, preserving heat for 4h/100mm, after the heat preservation is finished, cooling to less than or equal to 450 ℃ at a rate of less than or equal to 30 ℃/h, and discharging from the furnace for air cooling.
2. The method for improving 42CrMoA crankshaft band tissue according to claim 1, wherein the rapid cooling in the step 2) is air cooling or fog cooling.
3. The method for improving 42CrMoA crankshaft band-shaped structure according to claim 1, wherein in the step 1), when the intermediate blank is returned to the furnace for heating, the optimal temperature rise is 1250 +/-10 ℃, and the optimal heat preservation time is 15 h.
4. The method for improving 42CrMoA crankshaft band-shaped tissue according to claim 1, wherein in the step 2), when the temperature is raised at full power, the optimal temperature is 860 +/-10 ℃, the optimal heat preservation time is 1.5h/100mm, the temperature is cooled to 400-450 ℃ immediately after the heat preservation is finished, and the temperature is raised at full power to 650 +/-10 ℃.
5. The method for improving the 42CrMoA crankshaft band-shaped structure is characterized in that the 42CrMoA crankshaft is a vacuum refining die casting forged piece, and the chemical components of the steel for the crankshaft comprise 0.38-0.45 mass percent of carbon, 0.20-0.40 mass percent of silicon, 0.60-0.90 mass percent of manganese, 0.30-0.60 mass percent of nickel, 0.90-1.20 mass percent of chromium, 0.15-0.25 mass percent of molybdenum, 0.05-0.12 mass percent of vanadium and the balance of iron.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202210186512.6A CN114657363A (en) | 2022-02-28 | 2022-02-28 | Method for improving 42CrMoA crankshaft band-shaped structure |
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| CN202210186512.6A CN114657363A (en) | 2022-02-28 | 2022-02-28 | Method for improving 42CrMoA crankshaft band-shaped structure |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115679213A (en) * | 2022-11-01 | 2023-02-03 | 河南中原特钢装备制造有限公司 | Heat treatment process for controlling total section hardness difference of 42CrMo forge piece |
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| CN101487077A (en) * | 2009-03-04 | 2009-07-22 | 江苏金源锻造股份有限公司 | Isothermal normalizing method for alloy carburizing steel gear and forging shaft for wind power generator |
| CN102286655A (en) * | 2011-08-09 | 2011-12-21 | 浙江万能达炉业有限公司 | Device and method for isothermal normalizing utilizing forging waste heat |
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| CN114029435A (en) * | 2021-11-01 | 2022-02-11 | 内蒙古北方重工业集团有限公司 | Process method for eliminating steel strip-shaped structure of 40CrNiMoA crankshaft |
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2022
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115679213A (en) * | 2022-11-01 | 2023-02-03 | 河南中原特钢装备制造有限公司 | Heat treatment process for controlling total section hardness difference of 42CrMo forge piece |
| CN115679213B (en) * | 2022-11-01 | 2023-08-25 | 河南中原特钢装备制造有限公司 | Heat treatment process for controlling full-section hardness difference of 42CrMo forge piece |
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