US20120305147A1 - Method of manufacturing non-quenched and tempered steel product - Google Patents
Method of manufacturing non-quenched and tempered steel product Download PDFInfo
- Publication number
- US20120305147A1 US20120305147A1 US13/297,541 US201113297541A US2012305147A1 US 20120305147 A1 US20120305147 A1 US 20120305147A1 US 201113297541 A US201113297541 A US 201113297541A US 2012305147 A1 US2012305147 A1 US 2012305147A1
- Authority
- US
- United States
- Prior art keywords
- less
- quenched
- volume
- steel product
- warm
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Images
Classifications
-
- 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
- B21K1/00—Making machine elements
- B21K1/76—Making machine elements elements not mentioned in one of the preceding groups
- B21K1/766—Connecting rods
-
- 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
- B21K1/00—Making machine elements
- B21K1/76—Making machine elements elements not mentioned in one of the preceding groups
- B21K1/767—Toothed racks
-
- 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
- B21K1/00—Making machine elements
- B21K1/76—Making machine elements elements not mentioned in one of the preceding groups
-
- 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
- B21J5/06—Methods for forging, hammering, or pressing; Special equipment or accessories therefor for performing particular operations
-
- 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
- C21D1/26—Methods of annealing
-
- 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
- C21D7/00—Modifying the physical properties of iron or steel by deformation
- C21D7/13—Modifying the physical properties of iron or steel by deformation by hot working
-
- 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
- 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
- C21D9/0068—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for particular articles not mentioned below
-
- 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
- C21D7/00—Modifying the physical properties of iron or steel by deformation
- C21D7/02—Modifying the physical properties of iron or steel by deformation by cold working
- C21D7/04—Modifying the physical properties of iron or steel by deformation by cold working of the surface
- C21D7/06—Modifying the physical properties of iron or steel by deformation by cold working of the surface by shot-peening or the like
Definitions
- the present invention relates to a method of manufacturing a non-quenched and tempered (non-QT) steel product, particularly wherein the strength of the non-QT steel product is enhanced, and wherein the manufacturing process is drastically simplified.
- Enhancing the strength of products that include connecting rods made of a non-QT steel composition not subjected to quenching and tempering typically includes methods such as adding alloying components to the composition, and performing forging followed by controlled cooling to provide a fine-grain structure.
- a conventional connecting rod is deformed by hot forging, and is then subjected to shot blasting, cold coining so as to correct dimensions of bent portions and large/small ends, stress relief annealing for relieving residual stress produced upon coining, and then shot blasting so as to remove scales and make the surface smooth.
- shot blasting cold coining so as to correct dimensions of bent portions and large/small ends
- stress relief annealing for relieving residual stress produced upon coining
- shot blasting so as to remove scales and make the surface smooth.
- this method is problematic in terms of increased manufacturing cost due largely to the two shot blasting processes and the stress relief annealing.
- an insignificant enhancement in strength is achieved.
- forging is performed by introducing a rolling material between upper and lower molds having the shape of the product, and applying pressure thereto using a press, thus obtaining a desired shape.
- a final shape is obtained by carrying out two or three pressing processes, where typically three pressing processes are carried out which include buster, blocker, and finisher processes.
- the buster process greatly compresses the material to remove scales and keeps the forging ratio appropriate.
- the blocker process is performed so as to shape the material to its approximate final shape, thus making it possible to more efficiently perform the finisher process.
- the volumes at these respective steps are determined via simulation, including mold analysis, etc., upon designing the mold.
- the shot blasting process is performed by spraying fine particles of metal or non-metal, called shots or grits, onto the surface of a product to remove and mill scales.
- cold coining is conducted by placing the cooled forged product between coining molds and pressing it under a predetermined amount of pressure. This corrects the bending portions and controls the thickness of large or small ends. This process is used to improve the bending portion of a connecting rod or the like, not to form a novel shape.
- the present invention has been made keeping in mind the above problems encountered in the related art, with an object of providing an improved method of manufacturing a non-QT steel product.
- the method includes rapid cooling to providing a fine-grain structure and warm coining for hardening the structure, thus enhancing the strength or the product.
- the methods may omit continuous stress relief and shot blasting, thus increasing productivity and reducing the manufacturing cost.
- An aspect of the present invention provides a method of manufacturing a non-QT steel product, comprising hot forging a steel material at a heightened temperature (e.g., about 1150 ⁇ 1250° C.) so that the volume thereof is about 120% or less; rapidly cooling the hot forged material (e.g. cooling from the heightened temperature to about 650 ⁇ 700° C. at a cooling rate of about 10° C./s or more; and performing warm coining at a suitable temperature (e.g. about 600° C. or higher.
- a heightened temperature e.g., about 1150 ⁇ 1250° C.
- Another aspect of the present invention provides a method of manufacturing a non-QT steel product, comprising hot forging a steel material at a heightened temperature (e.g., about 1150 ⁇ 1250° C.) so that the volume thereof is about 120% or less; rapidly cooling the hot forged material; and warm coining four faces(top/bottom/left/right) of the material at a suitable temperature (e.g. about 600 ⁇ 680° C.) so that the volume thereof is about 100 ⁇ 120%.
- a heightened temperature e.g., about 1150 ⁇ 1250° C.
- a further aspect of the present invention provides a method of manufacturing a non-QT steel product, comprising hot forging a steel material at a heightened temperature (e.g., about 1150 ⁇ 1250° C.) so that the volume thereof is about 120% or less; rapidly cooling the hot forged material (e.g. cooling from the heightened temperature to about 650 ⁇ 700° C. at a cooling rate of about 10° C./s or more); and warm coining four faces (top/bottom/left/right) of the material at a suitable temperature (e.g. about 600 ⁇ 680° C.) so that the volume thereof is about 100 ⁇ 120%.
- a suitable temperature e.g. about 600 ⁇ 680° C.
- hot forging may be performed by processing the steel material so that the volume thereof is about 140% or less upon buster, about 130% or less upon blocker, and about 120% or less upon finisher.
- warm coining may further comprise transporting the coined material into a warm holding furnace at a suitable temperature (e.g. about 550 ⁇ 650° C.) so that residual stress is relieved.
- a suitable temperature e.g. about 550 ⁇ 650° C.
- transporting may further comprise performing shot blasting to remove scales from the transported material.
- the material may be a connecting rod for automobiles.
- FIG. 1 shows a conventional process of manufacturing a connecting rod
- FIG. 2 shows the shape of a material produced using conventional hot forging
- FIG. 3 shows a conventional cold coining process
- FIG. 4 shows a process of manufacturing a connecting rod according to an embodiment of the present invention.
- FIG. 5 shows a warm coining device used for the process of manufacturing the non-QT steel product of FIG. 4 .
- autonomous or other similar term as used herein is inclusive of motor vehicles in general such as passenger vehicles including sports utility vehicles (SUV), buses, trucks, various commercial vehicles, watercraft including a variety of boats and ships, aircraft, and the like, and includes hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles and other alternative fuel vehicles (e.g., fuels derived from resources other than petroleum).
- a hybrid vehicle is a vehicle that has two or more sources of power, for example both gasoline-powered and electric-powered vehicles.
- the term “about” is understood as within a range of normal tolerance in the art, for example within 2 standard deviations of the mean. About can be understood as within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated value. Unless otherwise clear from context, all numerical values provided herein are modified by the term about.
- FIG. 4 shows a process of manufacturing a non-QT steel product according to an embodiment of the present invention.
- the method of manufacturing a non-QT steel product comprises hot forging a steel material at a heightened temperature (e.g., about 1150 ⁇ 1250° C.) so that the volume thereof is 120% or less, rapidly cooling the hot forged material (e.g., cooling from the heightened temperature to about 650 ⁇ 700° C. at a cooling rate of about 10° C./s or more), and performing warm coining at a suitable temperature (e.g., about 600° C. or higher).
- a heightened temperature e.g., about 1150 ⁇ 1250° C.
- rapidly cooling the hot forged material e.g., cooling from the heightened temperature to about 650 ⁇ 700° C. at a cooling rate of about 10° C./s or more
- warm coining e.g., about 600° C. or higher.
- the method of manufacturing a non-QT steel product comprises hot forging a steel material at a heightened temperature (e.g. about 1150 ⁇ 1250° C.) so that the volume thereof is about 120% or less, rapidly cooling the hot forged material, and warm coining the four faces (top/bottom/left/right) of the material at a suitable temperature (e.g., about 600 ⁇ 680° C.) so that the volume thereof is about 100 ⁇ 120%.
- a heightened temperature e.g. about 1150 ⁇ 1250° C.
- suitable temperature e.g., about 600 ⁇ 680° C.
- the method of manufacturing a non-QT steel product comprises hot forging a steel material at a heightened temperature (e.g. about 1150 ⁇ 1250° C.) so that the volume thereof is about 120% or less, rapidly cooling the hot forged material (e.g. cooling from the heightened temperature to about 650 ⁇ 700° C. at a cooling rate of about 10° C./s or more), and warm coining four faces (top/bottom/left/right) of the material at a suitable temperature (e.g., about 600 ⁇ 680° C.) so that the volume thereof is about 100 ⁇ 120%.
- a suitable temperature e.g., about 600 ⁇ 680° C.
- the method of manufacturing a non-QT steel product according to the present invention generally includes hot forging, rapid cooling, and warm coining.
- One specific example of the non-QT steel product of the invention is a connecting rod for automobiles.
- a conventional cold coining process for treating bent portions thereof may be omitted from embodiments of the present invention, thus providing economic benefits.
- the non-QT steel composition of the present invention comprises about 0.30 ⁇ 0.60 wt % of C, about 0.50 ⁇ 2.0 wt % of Si, about 0.80 ⁇ 1.40 wt % of Mn, about 0.005 ⁇ 0.10 wt % of P, about 0.05 ⁇ 0.10 wt % of S, about 0.050 wt % or less but exceeding 0 wt % of Al, about 0.40 wt % or less but exceeding 0 wt % of Cr, about 0.05 ⁇ 0.35 wt % of V, about 0.15 wt % or less but exceeding 0 wt % of Ti, about 0.05 wt % or less but exceeding 0 wt % of Nb, about 0.010 ⁇ 0.080 wt % of Zr, about 0.030 wt % or less but exceeding 0 wt % of N, and a remainder of Fe and impurities.
- high-pressure nitrogen gas is blown thereon and rapid cooling (e.g. at about 10° C./s or more) is carried out until the temperature of the forged material is 680° C., which is just under the A1 transformation temperature.
- rapid cooling e.g. at about 10° C./s or more
- shot blasting is essentially performed because defects may occur while scales are trapped in the material upon cold coining.
- warm coining is performed at a temperature just under the A1 transformation temperature on the four faces of the top/bottom/left/right of the material so that the volume is 120% or less. This ensures fine dimensions and removes flash generated upon trimming. AS such, conventional milling of the sides can be omitted.
- FIG. 5 shows such a warm coining device, in which the material is compressed at the four faces of the top/bottom/left/right thereof so that the volume is controlled from 120% to about 100%.
- This warm coining process is different from a conventional coining process in which pressing is only performed at the top and bottom of a material.
- relatively simple corrections such as conventional correction of bending portions ( FIG. 3 ) can be performed.
- forming and correcting a material can be simultaneously carried out via heating in a heightened temperature atmosphere and processing the four faces.
- SRA stress relief annealing
- cold coining, shot blasting, and SRA are discontinuously performed using separate devices after hot forging and cooling. This undesirably decreases productivity.
- warm holding is continuously maintained after warm coining, and transporting and strengthening are simultaneously performed, thus increasing productivity.
- rapid cooling, warm coining for enhancing strength, and continuous warm holding processes according to the present invention make it possible to omit steps and improve the quality of the product.
- hot forging is performed so that the steel material is processed to a volume of about 140% or less upon buster, to about 130% or less upon blocker, and to about 120% or less upon finisher.
- the volume is controlled not to 100% but to 120% upon finisher, and the remaining 20% is treated by compression upon subsequent warm coining.
- the present inventions makes it possible to omit the shot blasting and cold coining steps.
- strength may be additionally enhanced by plastic deformation upon warm coining.
- the above warm coining process may further comprise transporting the coined material into a warm holding furnace at a suitable temperature, such as about 550 ⁇ 650° C., for relieving residual stress.
- transport and stress relief can be simultaneously carried out.
- Such transporting may further comprise shot blasting to remove scales from the transported material, and finally trimming the material.
- shot blasting may be performed a single time in contrast with conventional methods.
- the present invention provides a method of manufacturing a non-QT steel product.
- rapid cooling e.g. at about 10° C./sec or more
- warm coining for work hardening is then performed thus enhancing strength.
- continuous stress relief and shot blasting can be omitted, thus increasing the productivity and reducing the manufacturing process.
Abstract
This invention relates to a method of manufacturing a non-quenched and tempered steel product, including hot forging a steel material at about 1150˜1250° C. so that the volume thereof is 120% or less, rapidly cooling the hot forged material to about 650˜700° C. at a cooling rate of about 10° C./s or more, and performing warm coining at a temperature of about 600° C. or higher.
Description
- This application claims under 35 U.S.C. §119(a) priority to Korean Application No. 10-2011-0052563, filed on Jun. 1, 2011, the disclosure of which is incorporated herein by reference in its entirety.
- 1. Field of the Invention
- The present invention relates to a method of manufacturing a non-quenched and tempered (non-QT) steel product, particularly wherein the strength of the non-QT steel product is enhanced, and wherein the manufacturing process is drastically simplified.
- 2. Description of the Related Art
- Enhancing the strength of products that include connecting rods made of a non-QT steel composition not subjected to quenching and tempering typically includes methods such as adding alloying components to the composition, and performing forging followed by controlled cooling to provide a fine-grain structure.
- In order to enhance strength by adding alloying components, however, material costs increase significantly and, thus, provides limitations. In the case of forging followed by controlled cooling, the method is limited because the fastest cooling rate that can form a fine-grain structure is 5° C./s or less.
- As shown in
FIG. 1 , a conventional connecting rod is deformed by hot forging, and is then subjected to shot blasting, cold coining so as to correct dimensions of bent portions and large/small ends, stress relief annealing for relieving residual stress produced upon coining, and then shot blasting so as to remove scales and make the surface smooth. However, this method is problematic in terms of increased manufacturing cost due largely to the two shot blasting processes and the stress relief annealing. Furthermore, an insignificant enhancement in strength is achieved. - According to conventional forming processes, forging is performed by introducing a rolling material between upper and lower molds having the shape of the product, and applying pressure thereto using a press, thus obtaining a desired shape. As shown in
FIG. 2 , a final shape is obtained by carrying out two or three pressing processes, where typically three pressing processes are carried out which include buster, blocker, and finisher processes. When the volume of a final product is 100%, the volume is controlled to 120˜130% upon buster, 110˜120% upon blocker, and 100% upon finisher. For reference, the buster process greatly compresses the material to remove scales and keeps the forging ratio appropriate. After the buster process, the blocker process is performed so as to shape the material to its approximate final shape, thus making it possible to more efficiently perform the finisher process. The volumes at these respective steps are determined via simulation, including mold analysis, etc., upon designing the mold. - The shot blasting process is performed by spraying fine particles of metal or non-metal, called shots or grits, onto the surface of a product to remove and mill scales. As shown in
FIG. 3 , cold coining is conducted by placing the cooled forged product between coining molds and pressing it under a predetermined amount of pressure. This corrects the bending portions and controls the thickness of large or small ends. This process is used to improve the bending portion of a connecting rod or the like, not to form a novel shape. - This related art is merely utilized to enhance understanding about the background of the present invention, and will not be regarded as conventional techniques known to those having ordinary knowledge in the art.
- Accordingly, the present invention has been made keeping in mind the above problems encountered in the related art, with an object of providing an improved method of manufacturing a non-QT steel product. In particular, the method includes rapid cooling to providing a fine-grain structure and warm coining for hardening the structure, thus enhancing the strength or the product. Further, the methods may omit continuous stress relief and shot blasting, thus increasing productivity and reducing the manufacturing cost.
- An aspect of the present invention provides a method of manufacturing a non-QT steel product, comprising hot forging a steel material at a heightened temperature (e.g., about 1150˜1250° C.) so that the volume thereof is about 120% or less; rapidly cooling the hot forged material (e.g. cooling from the heightened temperature to about 650˜700° C. at a cooling rate of about 10° C./s or more; and performing warm coining at a suitable temperature (e.g. about 600° C. or higher.
- Another aspect of the present invention provides a method of manufacturing a non-QT steel product, comprising hot forging a steel material at a heightened temperature (e.g., about 1150˜1250° C.) so that the volume thereof is about 120% or less; rapidly cooling the hot forged material; and warm coining four faces(top/bottom/left/right) of the material at a suitable temperature (e.g. about 600˜680° C.) so that the volume thereof is about 100˜120%.
- A further aspect of the present invention provides a method of manufacturing a non-QT steel product, comprising hot forging a steel material at a heightened temperature (e.g., about 1150˜1250° C.) so that the volume thereof is about 120% or less; rapidly cooling the hot forged material (e.g. cooling from the heightened temperature to about 650˜700° C. at a cooling rate of about 10° C./s or more); and warm coining four faces (top/bottom/left/right) of the material at a suitable temperature (e.g. about 600˜680° C.) so that the volume thereof is about 100˜120%.
- In accordance with various embodiments, hot forging may be performed by processing the steel material so that the volume thereof is about 140% or less upon buster, about 130% or less upon blocker, and about 120% or less upon finisher.
- In some embodiments, warm coining may further comprise transporting the coined material into a warm holding furnace at a suitable temperature (e.g. about 550˜650° C.) so that residual stress is relieved.
- In some embodiments, transporting may further comprise performing shot blasting to remove scales from the transported material.
- According to embodiments of the present invention, the material may be a connecting rod for automobiles.
-
FIG. 1 shows a conventional process of manufacturing a connecting rod; -
FIG. 2 shows the shape of a material produced using conventional hot forging; -
FIG. 3 shows a conventional cold coining process; -
FIG. 4 shows a process of manufacturing a connecting rod according to an embodiment of the present invention; and -
FIG. 5 shows a warm coining device used for the process of manufacturing the non-QT steel product ofFIG. 4 . - Hereinafter, embodiments of the present invention regarding a method of manufacturing a non-QT steel product will be described in detail while referring to the accompanying drawings.
- It is understood that the term “automobile” or other similar term as used herein is inclusive of motor vehicles in general such as passenger vehicles including sports utility vehicles (SUV), buses, trucks, various commercial vehicles, watercraft including a variety of boats and ships, aircraft, and the like, and includes hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles and other alternative fuel vehicles (e.g., fuels derived from resources other than petroleum). As referred to herein, a hybrid vehicle is a vehicle that has two or more sources of power, for example both gasoline-powered and electric-powered vehicles.
- Unless specifically stated or obvious from context, as used herein, the term “about” is understood as within a range of normal tolerance in the art, for example within 2 standard deviations of the mean. About can be understood as within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated value. Unless otherwise clear from context, all numerical values provided herein are modified by the term about.
-
FIG. 4 shows a process of manufacturing a non-QT steel product according to an embodiment of the present invention. According to embodiments of the present invention, the method of manufacturing a non-QT steel product comprises hot forging a steel material at a heightened temperature (e.g., about 1150˜1250° C.) so that the volume thereof is 120% or less, rapidly cooling the hot forged material (e.g., cooling from the heightened temperature to about 650˜700° C. at a cooling rate of about 10° C./s or more), and performing warm coining at a suitable temperature (e.g., about 600° C. or higher). - In addition, the method of manufacturing a non-QT steel product according to embodiments of the present invention comprises hot forging a steel material at a heightened temperature (e.g. about 1150˜1250° C.) so that the volume thereof is about 120% or less, rapidly cooling the hot forged material, and warm coining the four faces (top/bottom/left/right) of the material at a suitable temperature (e.g., about 600˜680° C.) so that the volume thereof is about 100˜120%.
- In addition, the method of manufacturing a non-QT steel product according to embodiments of the present invention comprises hot forging a steel material at a heightened temperature (e.g. about 1150˜1250° C.) so that the volume thereof is about 120% or less, rapidly cooling the hot forged material (e.g. cooling from the heightened temperature to about 650˜700° C. at a cooling rate of about 10° C./s or more), and warm coining four faces (top/bottom/left/right) of the material at a suitable temperature (e.g., about 600˜680° C.) so that the volume thereof is about 100˜120%.
- Thus, the method of manufacturing a non-QT steel product according to the present invention generally includes hot forging, rapid cooling, and warm coining. One specific example of the non-QT steel product of the invention is a connecting rod for automobiles. In the case of such a connecting rod, a conventional cold coining process for treating bent portions thereof may be omitted from embodiments of the present invention, thus providing economic benefits.
- The non-QT steel composition of the present invention comprises about 0.30˜0.60 wt % of C, about 0.50˜2.0 wt % of Si, about 0.80˜1.40 wt % of Mn, about 0.005˜0.10 wt % of P, about 0.05˜0.10 wt % of S, about 0.050 wt % or less but exceeding 0 wt % of Al, about 0.40 wt % or less but exceeding 0 wt % of Cr, about 0.05˜0.35 wt % of V, about 0.15 wt % or less but exceeding 0 wt % of Ti, about 0.05 wt % or less but exceeding 0 wt % of Nb, about 0.010˜0.080 wt % of Zr, about 0.030 wt % or less but exceeding 0 wt % of N, and a remainder of Fe and impurities.
- In accordance with various embodiments, upon cooling after hot forging (so as to provide a volume of 120% or less), high-pressure nitrogen gas is blown thereon and rapid cooling (e.g. at about 10° C./s or more) is carried out until the temperature of the forged material is 680° C., which is just under the A1 transformation temperature. This results in the formation of fine crystal grains (which increases strength) and removal of scales. Thus, the conventional shot blasting process can be eliminated. As shown in the conventional process of
FIG. 1 , shot blasting is essentially performed because defects may occur while scales are trapped in the material upon cold coining. - Furthermore, according to embodiments of the invention, warm coining is performed at a temperature just under the A1 transformation temperature on the four faces of the top/bottom/left/right of the material so that the volume is 120% or less. This ensures fine dimensions and removes flash generated upon trimming. AS such, conventional milling of the sides can be omitted.
FIG. 5 shows such a warm coining device, in which the material is compressed at the four faces of the top/bottom/left/right thereof so that the volume is controlled from 120% to about 100%. This warm coining process, is different from a conventional coining process in which pressing is only performed at the top and bottom of a material. Thus, relatively simple corrections, such as conventional correction of bending portions (FIG. 3 ), can be performed. In particular, forming and correcting a material can be simultaneously carried out via heating in a heightened temperature atmosphere and processing the four faces. - Also, upon warm coining, strength may be additionally enhanced as a result of work hardening effects due to plastic deformation. After warm coining, the material is held in a heated belt conveyor furnace, e.g. at about 600° C. for about 20 minutes or longer, to relieve residual stress. As such, the material may be simultaneously transported and strengthened. Further, according to the present invention, stress relief annealing (SRA) using conventional cold coining may be omitted, thus reducing the manufacturing cost.
- According to conventional methods, cold coining, shot blasting, and SRA are discontinuously performed using separate devices after hot forging and cooling. This undesirably decreases productivity. In contrast, according to embodiments of the present invention, warm holding is continuously maintained after warm coining, and transporting and strengthening are simultaneously performed, thus increasing productivity. Further, the rapid cooling, warm coining for enhancing strength, and continuous warm holding processes according to the present invention make it possible to omit steps and improve the quality of the product.
- In particular, according to embodiments of the present invention, hot forging is performed so that the steel material is processed to a volume of about 140% or less upon buster, to about 130% or less upon blocker, and to about 120% or less upon finisher. In contrast, in conventional methods, the volume is controlled not to 100% but to 120% upon finisher, and the remaining 20% is treated by compression upon subsequent warm coining. Thus, the present inventions makes it possible to omit the shot blasting and cold coining steps. Also, according to the present invention, strength may be additionally enhanced by plastic deformation upon warm coining.
- Also, according to various embodiments of the present invention, the above warm coining process may further comprise transporting the coined material into a warm holding furnace at a suitable temperature, such as about 550˜650° C., for relieving residual stress. As such, transport and stress relief can be simultaneously carried out. Such transporting may further comprise shot blasting to remove scales from the transported material, and finally trimming the material. According to the present invention, shot blasting may be performed a single time in contrast with conventional methods.
- As described hereinbefore, the present invention provides a method of manufacturing a non-QT steel product. According to the present invention, after a forging process, rapid cooling (e.g. at about 10° C./sec or more) is performed to achieving a fine structure, and warm coining for work hardening is then performed thus enhancing strength. Further, continuous stress relief and shot blasting can be omitted, thus increasing the productivity and reducing the manufacturing process.
- Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.
Claims (15)
1. A method of manufacturing a non-quenched and tempered steel product, comprising:
hot forging a steel material at about 1150˜1250° C. so that a volume thereof is about 120% or less;
rapidly cooling, by high pressure liquid nitrogen, the hot forged material to about 650˜700° C. at a cooling rate of about 10° C./s or more; and
performing warm coining at a temperature of about 600° C. or higher on the rapidly cooled material,
wherein the non-quenched and tempered steel product is produced without spot blasting the material.
2. A method of manufacturing a non-quenched and tempered steel product, comprising:
hot forging a steel material at about 1150˜1250° C. so that a volume thereof is about 120% or less;
rapidly cooling the hot forged material, by high pressure liquid nitrogen to a temperature of 680° C. or less; and
once the hot forged material has been rapidly cooled to 680° C. or less, warm coining four faces of top/bottom/left/right of the material at about 600˜680° C. so that the volume thereof is about 100˜120% on the rapidly cooled material
wherein the non-quenched and tempered steel product is produced without spot blasting the material.
3. A method of manufacturing a non-quenched and tempered steel product, comprising:
hot forging a steel material at about 1150˜1250° C. so that a volume thereof is about 120% or less;
rapidly cooling, by high pressure liquid nitrogen, the hot forged material to about 650˜700° C. at a cooling rate of about 10° C./s or more; and
once the hot forged material has been rapidly cooled to about 650˜700° C., warm coining four faces of top/bottom/left/right of the material at about 600˜680° C. so that the volume thereof is about 100˜120% on the rapidly cooled material,
wherein the non-quenched and tempered steel product is produced without spot blasting the material.
4. The method of claim 1 , wherein the hot forging is performed by processing the steel material so that the volume thereof is about 140% or less upon buster, about 130% or less upon blocker, and about 120% or less upon finisher.
5. The method of claim 2 , wherein the hot forging is performed by processing the steel material so that the volume thereof is about 140% or less upon buster, about 130% or less upon blocker, and about 120% or less upon finisher.
6. The method of claim 3 , wherein the hot forging is performed by processing the steel material so that the volume thereof is about 140% or less upon buster, about 130% or less upon blocker, and about 120% or less upon finisher.
7. The method of claim 1 , wherein the warm coining further comprises transporting the coined material into a warm holding furnace at about 550˜650° C. so that residual stress is relieved.
8. The method of claim 2 , wherein the warm coining further comprises transporting the coined material into a warm holding furnace at about 550˜650° C. so that residual stress is relieved.
9. The method of claim 3 , wherein the warm coining further comprises transporting the coined material into a warm holding furnace at about 550˜650° C. so that residual stress is relieved.
10. The method of claim 7 , wherein the transporting further comprises performing shot blasting for removing scales from the transported material.
11. The method of claim 8 , wherein the transporting further comprises performing shot blasting for removing scales from the transported material.
12. The method of claim 9 , wherein the transporting further comprises performing shot blasting for removing scales from the transported material.
13. The method claim 1 , wherein the non-quenched and tempered steel product is a connecting rod for automobiles.
14. The method claim 2 , wherein the non-quenched and tempered steel product is a connecting rod for automobiles.
15. The method claim 3 , wherein the non-quenched and tempered steel product is a connecting rod for automobiles.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
KR10-2011-0052563 | 2011-06-01 | ||
KR1020110052563A KR101284294B1 (en) | 2011-06-01 | 2011-06-01 | Producing method for non quenched and tempered steel product |
Publications (1)
Publication Number | Publication Date |
---|---|
US20120305147A1 true US20120305147A1 (en) | 2012-12-06 |
Family
ID=47230258
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US13/297,541 Abandoned US20120305147A1 (en) | 2011-06-01 | 2011-11-16 | Method of manufacturing non-quenched and tempered steel product |
Country Status (3)
Country | Link |
---|---|
US (1) | US20120305147A1 (en) |
KR (1) | KR101284294B1 (en) |
CN (1) | CN102806289B (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN110253221A (en) * | 2019-06-19 | 2019-09-20 | 云南西仪工业股份有限公司 | A method of for connecting rod blank destressing |
CN110819772A (en) * | 2019-10-28 | 2020-02-21 | 鞍钢股份有限公司 | Nitrogen-hydrogen protective gas control method for continuous annealing furnace |
US20210094088A1 (en) * | 2019-09-30 | 2021-04-01 | Hyundai Motor Company | Method and apparatus for manufacturing a forged component |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH10258335A (en) * | 1997-03-17 | 1998-09-29 | Nissan Motor Co Ltd | Manufacture of connecting rod |
EP1120598A1 (en) * | 2000-01-24 | 2001-08-01 | Praxair Technology, Inc. | Method of using high pressure liquid nitrogen for cooling reactors |
JP2005240149A (en) * | 2004-02-27 | 2005-09-08 | Daido Steel Co Ltd | Low toughness-ductility free cutting non-quenched and tempered steel |
US20060000088A1 (en) * | 2003-03-18 | 2006-01-05 | Tatsuya Hasegawa | Non-heat treated connecting rod and method of manufacturing the same |
US20060124211A1 (en) * | 2004-10-29 | 2006-06-15 | Takashi Takano | Steel pipe for an airbag inflator and a process for its manufacture |
US20090308504A1 (en) * | 2006-03-31 | 2009-12-17 | Jft Steel Corporation, A Corporation Of Japan | Steel sheet excellent in fine blanking performance and manufacturing method of the same |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP3536770B2 (en) * | 2000-03-17 | 2004-06-14 | 住友金属工業株式会社 | Non-heat treated steel |
JP5023410B2 (en) * | 2001-03-02 | 2012-09-12 | 大同特殊鋼株式会社 | Non-tempered steel for hot forging with easy fracture separation |
KR100435317B1 (en) * | 2001-07-02 | 2004-06-10 | 현대자동차주식회사 | Manufacturing method of hotforging splitsteel connectingrod |
JP2006052432A (en) * | 2004-08-10 | 2006-02-23 | Nissan Motor Co Ltd | Method for manufacturing forged product for connecting rod easily separated through rupture and having high-strength |
JP5268715B2 (en) * | 2009-03-05 | 2013-08-21 | 株式会社三條機械製作所 | Manufacturing method of connecting rod and coining type apparatus used therefor |
-
2011
- 2011-06-01 KR KR1020110052563A patent/KR101284294B1/en active IP Right Grant
- 2011-11-16 US US13/297,541 patent/US20120305147A1/en not_active Abandoned
- 2011-11-29 CN CN201110386358.9A patent/CN102806289B/en not_active Expired - Fee Related
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH10258335A (en) * | 1997-03-17 | 1998-09-29 | Nissan Motor Co Ltd | Manufacture of connecting rod |
EP1120598A1 (en) * | 2000-01-24 | 2001-08-01 | Praxair Technology, Inc. | Method of using high pressure liquid nitrogen for cooling reactors |
US20060000088A1 (en) * | 2003-03-18 | 2006-01-05 | Tatsuya Hasegawa | Non-heat treated connecting rod and method of manufacturing the same |
JP2005240149A (en) * | 2004-02-27 | 2005-09-08 | Daido Steel Co Ltd | Low toughness-ductility free cutting non-quenched and tempered steel |
US20060124211A1 (en) * | 2004-10-29 | 2006-06-15 | Takashi Takano | Steel pipe for an airbag inflator and a process for its manufacture |
US20090308504A1 (en) * | 2006-03-31 | 2009-12-17 | Jft Steel Corporation, A Corporation Of Japan | Steel sheet excellent in fine blanking performance and manufacturing method of the same |
Non-Patent Citations (3)
Title |
---|
Kim et al. "Development of an expert system for the process design of axisymmetric hot steel forging", Journal of Material Processing Technology, 101, 2000, 223-230. * |
Machine translation of JP 10258335, 1998. * |
Machine translation of JP 2005240149, 2005. * |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN110253221A (en) * | 2019-06-19 | 2019-09-20 | 云南西仪工业股份有限公司 | A method of for connecting rod blank destressing |
US20210094088A1 (en) * | 2019-09-30 | 2021-04-01 | Hyundai Motor Company | Method and apparatus for manufacturing a forged component |
US11633779B2 (en) * | 2019-09-30 | 2023-04-25 | Hyundai Motor Company | Method and apparatus for manufacturing a forged component |
CN110819772A (en) * | 2019-10-28 | 2020-02-21 | 鞍钢股份有限公司 | Nitrogen-hydrogen protective gas control method for continuous annealing furnace |
Also Published As
Publication number | Publication date |
---|---|
KR101284294B1 (en) | 2013-07-08 |
CN102806289A (en) | 2012-12-05 |
KR20120133745A (en) | 2012-12-11 |
CN102806289B (en) | 2016-09-21 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US20200370155A1 (en) | High strength aluminum stamping | |
KR20230142648A (en) | High intensity corrosion resistance 6XXX series aluminum alloy and a method of manufacture thereof | |
KR102144194B1 (en) | Method of manufacturing hot stamping parts | |
KR20190108125A (en) | Rapid Aging Treatment of High Strength 7XXX Aluminum Alloy and How to Prepare the Alloy | |
CN103820726A (en) | Method for manufacturing bolts with relatively high fatigue strength | |
US20100319426A1 (en) | Method for producing press-hardened components for motor vehicles | |
CN106460107A (en) | Al-casting alloy | |
JP2023030011A (en) | Methods of making highly-formable aluminum alloys and aluminum alloy products thereof | |
JP5729213B2 (en) | Manufacturing method of hot press member | |
US20120305147A1 (en) | Method of manufacturing non-quenched and tempered steel product | |
CN116043145A (en) | Method for warm forming an age-hardenable aluminium alloy in a T4 temper | |
CN109440006B (en) | Baking hardened steel for automobile outer plate and production method thereof | |
KR102042062B1 (en) | Steel wire rod for cold forging and methods for manufacturing thereof | |
EP2479305A1 (en) | Method of manufacturing a structural automotive part made from a rolled Al-Zn alloy | |
CN110229981B (en) | Forging forming method for aluminum alloy straight thrust rod joint | |
JP3562198B2 (en) | Manufacturing method of connecting rod | |
CN105603306A (en) | Dual-phase steel with transformation induced plasticity characteristic and production method thereof | |
CN116159954A (en) | Method for producing forging molded article | |
KR20190078129A (en) | Steel wire rod for cold forging, processed good using the same, and methods for manufacturing thereof | |
KR101481909B1 (en) | Manufacturing method of magnesium alloy | |
CN111549296A (en) | Heat-resistant steel for automobile fastener and production method thereof | |
CN110709530B (en) | Aluminum alloy product with low texture and manufacturing method thereof | |
CN104789744B (en) | Heat treatment method of high-strength automobile frame | |
US11739404B2 (en) | Method for manufacturing aluminum alloy plastically-processed article | |
JP5057299B2 (en) | Steel plate for strength gradient member and method for producing the same |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: HYUNDAI MOTOR COMPANY, KOREA, REPUBLIC OF Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:LEE, CHANG KU;REEL/FRAME:027236/0166 Effective date: 20111017 |
|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |