CA2128019C - High-strength steel parts and method of making - Google Patents
High-strength steel parts and method of makingInfo
- Publication number
- CA2128019C CA2128019C CA002128019A CA2128019A CA2128019C CA 2128019 C CA2128019 C CA 2128019C CA 002128019 A CA002128019 A CA 002128019A CA 2128019 A CA2128019 A CA 2128019A CA 2128019 C CA2128019 C CA 2128019C
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- Prior art keywords
- strength
- blank
- psi
- mpa
- strength steel
- Prior art date
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- Expired - Lifetime
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Classifications
-
- 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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/02—Hardening articles or materials formed by forging or rolling, with no further heating beyond that required for the formation
-
- 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
-
- 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
-
- 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
- C21D9/0093—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for screws; for bolts
-
- 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
- C21D2211/008—Martensite
-
- 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
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Crystallography & Structural Chemistry (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Forging (AREA)
- Heat Treatment Of Steel (AREA)
- Heat Treatment Of Articles (AREA)
Abstract
High strength steel parts and method of making are disclosed by providing a blank of high-strength steel material having a tensile strength of at least about 120,000 psi and a yield strength or at least about 90,000 psi and warm forming the blank to provide the part of desired geometric configuration while substantially maintaining or increasing the strength properties of the blank.
Description
HIGH-STRENGTH STEEL PARTS AND METHOD OF MAKING SAME
Field of the Invention The present invention relates to a method of making high-strength steel parts and the parts produced thereby, and more particularly it relates to a method in which a blank of high-strength steel is warm formed into a desired geometric configuration while maintaining the high-strength properties of the steel blank.
Background of the Invention Steel parts have heretofore been formed using cold forging or hot forging techniques which are well known in the art. In hot forging parts from steel, the material is initially heated to about 2000~F and higher. At these hot forging temperatures, substantial scale and decarburization of the steel ~093/1~233 2 ~ ~ t 1 PCT/US93/~519 -occurs. Since the scale and decarburized surfaces must be removed to obtain the finished part, known hot forging techniques result in the waste of a certain amount of material; furthermore, such techniques are 5 costly due to increased processing steps required to remove the scale and the higher energy consumption because of the high temperatures. On the other hand, there are drawbacks to cold forming parts as well.
Since the part is formed at or about room temperature, the reshaping or forming steps require substantially higher forces. This frequently necessitates a series of cold forming steps in which the material is formed into the desired part gradually. This increases die wear and noise associated with such processes.
Furthermore, if the material is worked to a substantial degree over a series of forming stages, the strength of the part is increased and the part must therefore be annealed between successive cold forming operations to relieve internal stress, which adds to the time and cost of such processes.
- To avoid the above drawbacks, warm forging may be utilized to form parts from materials at an intermediate temperature which is high enough to reduce the strength of the material and thereby facilitate forming, and yet is below the hot forging temperature at which scaling and decarburization occurs. One such warm forming method is disclosed in U.S. Pat. No. 3,557,587. Certain other patents disclose processes which include rolling and extruding steps carried out at "warm" temperatures so as to avoid the drawbacks of decarburization and scaling and/or to impart or improve desired metallurgical and mechanical properties to the steel. See U.S.
Pat. Nos. 2,767,836; 2,767,837; 2,880,855; 3,076,361; 3,573,999, and "Warm Working of Steel", Gokyu, et al, translation of the Japanese Institute of Metal, 1968, Volume 9, Supplement, Pages 177-181 .
Additionally, there are other known methods for bending or forging steel bars, rods or billets to form a desired product which methods include a warm forming or warm forging step. See U.S. Pat. Nos. 2,953,794; 3,720,087; 3,877,821; 4,312,210;
4,317,355; 4,608,851 and 4,805,437. No representation is made that any of the above cited references fairly represent the prior art or that such references are the most material references.
U.S. Patent Nos. 3,001,897 and 3,904,445 both describe methods of forming a blank of high strength steel for subsequent use to form parts. The former Patent describes a method in which steel is first cold reduced and then further reduced to the final gauge at a warm temperature. The latter Patent describes a method in which steel is processed into bar stock by hot reduction to the final gauge, rapid cooling and cold finishing.
The stock is then stress relieved at a warm temperature.
Abstract No. 101411, Chemical Abstracts Vol. 95, No.
11, (Japanese Patent Application No. 56-4612) describes a method of forming bolts from hardened steel rods containing 0.15-0.4 carbon in which a rod is hot-rolled, water cooled, cold-drawn, ~ CA 02128019 1998-07-14 heated to 550~C, hot shaped to bolts and then water cooled. The tensile strength of the products is at least 100 kg/mm2.
U.S. Patent No. 3,959,999 describes a method of producing long articles such as wire, strip and rolled sections, from hot rolled carbon steel by preforming alternate cold and warm plastic deformations of a rod at least twice in succession.
U.S. Patent No. 3,720,087 describes a process for bending steel bars or rods to effect a desired curvature or straightness at a temperature in the range 150~C to 480~C. The strength properties of the bars or rods are retained provided the steel is one which strain or work hardens.
A method of making high-strength steel parts, in accordance with the invention, comprises providing a blank of high-strength steel material having a tensile strength of at least 800 MPa (120,000 psi) and a yield strength of at least 600 MPa (90,000 psi) and warm forming the blank at a temperature between 150~C (300~F) to 650~C (1200~F) to provide a part having a desired geometric configuration, whereby the mechanical properties of tensile strength and yield strength of the part are greater than the blank wherein the high-strength steel material comprises, by weight percent:
carbon 0.30 to 0.65 manganese 0.30 to 2.5 vanadium up to 0.35 iron balance.
There is thus provided, which has heretofore been lacking, a method of making a high-strength steel part from a blank of steel possessing desired high-strength properties, which method includes a warm forming step whereby the blank is formed into a desired part and whereby the mechanical properties of the part are greater than those originally possessed by the blank, and in which the part is, preferably, produced without additional strengthening processing steps to impart mechanical strength properties to the steel part.
The present invention is directed to a method of making high-strength steel parts from blanks of high-strength steel material having a tensile strength of at least about 800 MPa (120,000 psi) and a yield strength of at least about 600 MPa (90, 000 psi) .
In one of its aspects, the present invention provides a method of making high-strength steel parts from blanks of high-strength steel material by warm forming the blank to provide a part having a desired geometric configuration, whereby the mechanical properties of tensile strength and yield strength of the part are greater than the blank.
The present invention also provides a method of making high-strength steel parts including warm forming a blank of high-strength steel material whereby the mechanical properties oftensile strength and yield strength of the part are substantially the same as or greater than the blank and wherein the part, with the desired mechanical properties of tensile strength and yield strength, is produced without further strengthening processing steps. High-strength steel parts are produced in accordance with the method of this invention.
The principles of this invention, its objectives and advantages will be further understood with reference to the following detailed description.
Detailed Description of the Invention The method of the present invention is useful for producing a wide variety of high-strength steel parts including various types of bolts (U-bolts, eye-bolts, ~-bolts, hex-head bolts, square-head bolts, etc.), axles, cam shafts, screws, sway bars and other parts susceptible to forming by the warm forging or forming process disclosed herein.
In a preferred embodiment, the method for making a high-strength steel part includes providing a blank of high-strength steel material having a tensile strength of at least about 800 MPa (120,000 psi), and preferably at least about 1025 MPa (150,000 psi), and a yield strength of at least about 600 MPa (90,000 psi), and preferably at least about 900 MPa (130,000 psi). In one form, the high-strength steel material utilized as the blank has been hot reduced and cold drawn to provide the blank having the mechanical properties of tensile strength and yield strength stated above.
The high-strength steel material may be exemplified by the following composition, by weight percent:
carbon about 0.30 to about 0.65 manganese about 0.30 to about 2.5 vanadium up to about 0.35 iron balance.
In a more preferred form, the high-strength steel material has the following composition, by weight percent:
carbon about 0.50 to about 0.55 manganese about 1.20 to about 1.65 vanadium about 0.03 to about 0.15 iron balance.
The blank, having a composition and mechanical properties of tensile strength and yield strength as given above, is thereafter warm formed at a temperature of about 150~C (300~F) to about 650~C (1200~F) to provide a part having a desired geometric configuration, whereby the mechanical properties of tensile strength and yield strength of the part are greater than the blank. The temperature at which the part is formed is related to the chemical composition of the steel material used.
The formed part, with the mechanical properties of tensile strength and yield strength given, is produced without any further strengthening processing steps subsequent to the warm forming thereof.
The blank of high-strength steel material having a tensile strength of at least about 800 MPa (120,000 psi) and a yield strength of at least about 600 MPa (90,000 psi), which is used as the starting piece in the method of the present invention is produced by any suitable method known in the art. One such method is disclosed in U.S. Patent No. 3,904,445 which discloses a processing sequence to produce a high-strength steel bar stock of the type particularly useful for producing threaded fasteners, including U-bolts. In the described process, the bar stock produced has a fine grained structure between about ASTM No. 5-8. In the disclosed process, a steel, having a chemistry falling within certain disclosed ranges, is subjected to a standard hot reducing operation to within 10~-15~ of final gauge. The hot reduced bar stock is then cut or severed into individual lengths for rapid air cooling. Thereafter the individual lengths of hot reduced bar stock are subjected to a cold finishing to final gauge. The final step is a controlled stress relieving step to increase the mechanical strength properties. This stress relieving step comprises heating the lengths of bar stock to between about 260-450~C (500-850~F) for about 1 hour, but may or may not be necessary. Thus, such bar stock, with and without further stress relieving may be used to form the starting blank material of high-strength steel.
The following examples illustrate the practice of the present invention to produce a U-bolt from high-strength steel bar stock produced in accordance with thé method disclosed in U.S. Pat. No. 3,904,445, described above.
ExamPle 1 High-strength steel bar stock of Grade 8 strength steel, having a diameter of 2.1 cm (0.825"), is cut to lengths of approximately 90 cm (36.0"). This stock has a tensile strength of at least about 1025 MPa (150,000 psi) and a yield strength of at least about 900 MPa (130,000 psi). Both ends of the bar stock segments are threaded using known threading processes to provide 6.4 cm (2~") threaded sections at either end thereof. The bar stock segments are then heated to approximately 450~C (850~F) and a medial section of each bar stock segment is flattened using a mechanical forging press applying approximately 100 MPa (1,000 tons) of pressure. The flattened section of the bar stock is approximately 1.1 cm (7/16") thick and 3.2 cm (1~
wide. Thereafter, the bar stock segments are bent at the location of the flattened section to form the U-bolt product.
The flattening step provides elongation to the bar stock segment such that the total length of the finished U-bolt product is somewhat in excess of 90 cm (36"). The finished U-bolt product has the desired mechanical properties of tensile strength and yield strength originally possessed by the bar stock and therefore requires no further strengthening processing steps.
~ 9 Examples 2-6 Five high-strength cold drawn C-1541 steel bars having diameters of about 18.3 mm (O.72") were cut to lengths of approximately 46 cm (18'l). These bars were turned down to diameters of about 1.25 cm (0.5") and tested for mechanical properties reported in Table I. For instance, these bars had tensile strengths of about 960 MPa (140,000 psi) and yield strengths of about 900 MPa (130,000 psi) as set forth in Table I.
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- . -Examples 7-11 Five high-strength cold drawn C-1541 steel bars having diameters of about 18.3 mm (0.72") were cut to lengths of approximately 46.0 cm (18") from the same length of bar stock used to make bars of Examples 2-6. The bars were then heated to approximately 270~C (550~F) and a medial section of each bar was flattened in a fashion similar to Example 1 using a mechanical forging press applying approximately 100 MPa (1,000 tons) of pressure.
The flattened bars were then turned down to a diameter of about 1.25 cm (0.5") and tested for the properties listed in Table II.
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Field of the Invention The present invention relates to a method of making high-strength steel parts and the parts produced thereby, and more particularly it relates to a method in which a blank of high-strength steel is warm formed into a desired geometric configuration while maintaining the high-strength properties of the steel blank.
Background of the Invention Steel parts have heretofore been formed using cold forging or hot forging techniques which are well known in the art. In hot forging parts from steel, the material is initially heated to about 2000~F and higher. At these hot forging temperatures, substantial scale and decarburization of the steel ~093/1~233 2 ~ ~ t 1 PCT/US93/~519 -occurs. Since the scale and decarburized surfaces must be removed to obtain the finished part, known hot forging techniques result in the waste of a certain amount of material; furthermore, such techniques are 5 costly due to increased processing steps required to remove the scale and the higher energy consumption because of the high temperatures. On the other hand, there are drawbacks to cold forming parts as well.
Since the part is formed at or about room temperature, the reshaping or forming steps require substantially higher forces. This frequently necessitates a series of cold forming steps in which the material is formed into the desired part gradually. This increases die wear and noise associated with such processes.
Furthermore, if the material is worked to a substantial degree over a series of forming stages, the strength of the part is increased and the part must therefore be annealed between successive cold forming operations to relieve internal stress, which adds to the time and cost of such processes.
- To avoid the above drawbacks, warm forging may be utilized to form parts from materials at an intermediate temperature which is high enough to reduce the strength of the material and thereby facilitate forming, and yet is below the hot forging temperature at which scaling and decarburization occurs. One such warm forming method is disclosed in U.S. Pat. No. 3,557,587. Certain other patents disclose processes which include rolling and extruding steps carried out at "warm" temperatures so as to avoid the drawbacks of decarburization and scaling and/or to impart or improve desired metallurgical and mechanical properties to the steel. See U.S.
Pat. Nos. 2,767,836; 2,767,837; 2,880,855; 3,076,361; 3,573,999, and "Warm Working of Steel", Gokyu, et al, translation of the Japanese Institute of Metal, 1968, Volume 9, Supplement, Pages 177-181 .
Additionally, there are other known methods for bending or forging steel bars, rods or billets to form a desired product which methods include a warm forming or warm forging step. See U.S. Pat. Nos. 2,953,794; 3,720,087; 3,877,821; 4,312,210;
4,317,355; 4,608,851 and 4,805,437. No representation is made that any of the above cited references fairly represent the prior art or that such references are the most material references.
U.S. Patent Nos. 3,001,897 and 3,904,445 both describe methods of forming a blank of high strength steel for subsequent use to form parts. The former Patent describes a method in which steel is first cold reduced and then further reduced to the final gauge at a warm temperature. The latter Patent describes a method in which steel is processed into bar stock by hot reduction to the final gauge, rapid cooling and cold finishing.
The stock is then stress relieved at a warm temperature.
Abstract No. 101411, Chemical Abstracts Vol. 95, No.
11, (Japanese Patent Application No. 56-4612) describes a method of forming bolts from hardened steel rods containing 0.15-0.4 carbon in which a rod is hot-rolled, water cooled, cold-drawn, ~ CA 02128019 1998-07-14 heated to 550~C, hot shaped to bolts and then water cooled. The tensile strength of the products is at least 100 kg/mm2.
U.S. Patent No. 3,959,999 describes a method of producing long articles such as wire, strip and rolled sections, from hot rolled carbon steel by preforming alternate cold and warm plastic deformations of a rod at least twice in succession.
U.S. Patent No. 3,720,087 describes a process for bending steel bars or rods to effect a desired curvature or straightness at a temperature in the range 150~C to 480~C. The strength properties of the bars or rods are retained provided the steel is one which strain or work hardens.
A method of making high-strength steel parts, in accordance with the invention, comprises providing a blank of high-strength steel material having a tensile strength of at least 800 MPa (120,000 psi) and a yield strength of at least 600 MPa (90,000 psi) and warm forming the blank at a temperature between 150~C (300~F) to 650~C (1200~F) to provide a part having a desired geometric configuration, whereby the mechanical properties of tensile strength and yield strength of the part are greater than the blank wherein the high-strength steel material comprises, by weight percent:
carbon 0.30 to 0.65 manganese 0.30 to 2.5 vanadium up to 0.35 iron balance.
There is thus provided, which has heretofore been lacking, a method of making a high-strength steel part from a blank of steel possessing desired high-strength properties, which method includes a warm forming step whereby the blank is formed into a desired part and whereby the mechanical properties of the part are greater than those originally possessed by the blank, and in which the part is, preferably, produced without additional strengthening processing steps to impart mechanical strength properties to the steel part.
The present invention is directed to a method of making high-strength steel parts from blanks of high-strength steel material having a tensile strength of at least about 800 MPa (120,000 psi) and a yield strength of at least about 600 MPa (90, 000 psi) .
In one of its aspects, the present invention provides a method of making high-strength steel parts from blanks of high-strength steel material by warm forming the blank to provide a part having a desired geometric configuration, whereby the mechanical properties of tensile strength and yield strength of the part are greater than the blank.
The present invention also provides a method of making high-strength steel parts including warm forming a blank of high-strength steel material whereby the mechanical properties oftensile strength and yield strength of the part are substantially the same as or greater than the blank and wherein the part, with the desired mechanical properties of tensile strength and yield strength, is produced without further strengthening processing steps. High-strength steel parts are produced in accordance with the method of this invention.
The principles of this invention, its objectives and advantages will be further understood with reference to the following detailed description.
Detailed Description of the Invention The method of the present invention is useful for producing a wide variety of high-strength steel parts including various types of bolts (U-bolts, eye-bolts, ~-bolts, hex-head bolts, square-head bolts, etc.), axles, cam shafts, screws, sway bars and other parts susceptible to forming by the warm forging or forming process disclosed herein.
In a preferred embodiment, the method for making a high-strength steel part includes providing a blank of high-strength steel material having a tensile strength of at least about 800 MPa (120,000 psi), and preferably at least about 1025 MPa (150,000 psi), and a yield strength of at least about 600 MPa (90,000 psi), and preferably at least about 900 MPa (130,000 psi). In one form, the high-strength steel material utilized as the blank has been hot reduced and cold drawn to provide the blank having the mechanical properties of tensile strength and yield strength stated above.
The high-strength steel material may be exemplified by the following composition, by weight percent:
carbon about 0.30 to about 0.65 manganese about 0.30 to about 2.5 vanadium up to about 0.35 iron balance.
In a more preferred form, the high-strength steel material has the following composition, by weight percent:
carbon about 0.50 to about 0.55 manganese about 1.20 to about 1.65 vanadium about 0.03 to about 0.15 iron balance.
The blank, having a composition and mechanical properties of tensile strength and yield strength as given above, is thereafter warm formed at a temperature of about 150~C (300~F) to about 650~C (1200~F) to provide a part having a desired geometric configuration, whereby the mechanical properties of tensile strength and yield strength of the part are greater than the blank. The temperature at which the part is formed is related to the chemical composition of the steel material used.
The formed part, with the mechanical properties of tensile strength and yield strength given, is produced without any further strengthening processing steps subsequent to the warm forming thereof.
The blank of high-strength steel material having a tensile strength of at least about 800 MPa (120,000 psi) and a yield strength of at least about 600 MPa (90,000 psi), which is used as the starting piece in the method of the present invention is produced by any suitable method known in the art. One such method is disclosed in U.S. Patent No. 3,904,445 which discloses a processing sequence to produce a high-strength steel bar stock of the type particularly useful for producing threaded fasteners, including U-bolts. In the described process, the bar stock produced has a fine grained structure between about ASTM No. 5-8. In the disclosed process, a steel, having a chemistry falling within certain disclosed ranges, is subjected to a standard hot reducing operation to within 10~-15~ of final gauge. The hot reduced bar stock is then cut or severed into individual lengths for rapid air cooling. Thereafter the individual lengths of hot reduced bar stock are subjected to a cold finishing to final gauge. The final step is a controlled stress relieving step to increase the mechanical strength properties. This stress relieving step comprises heating the lengths of bar stock to between about 260-450~C (500-850~F) for about 1 hour, but may or may not be necessary. Thus, such bar stock, with and without further stress relieving may be used to form the starting blank material of high-strength steel.
The following examples illustrate the practice of the present invention to produce a U-bolt from high-strength steel bar stock produced in accordance with thé method disclosed in U.S. Pat. No. 3,904,445, described above.
ExamPle 1 High-strength steel bar stock of Grade 8 strength steel, having a diameter of 2.1 cm (0.825"), is cut to lengths of approximately 90 cm (36.0"). This stock has a tensile strength of at least about 1025 MPa (150,000 psi) and a yield strength of at least about 900 MPa (130,000 psi). Both ends of the bar stock segments are threaded using known threading processes to provide 6.4 cm (2~") threaded sections at either end thereof. The bar stock segments are then heated to approximately 450~C (850~F) and a medial section of each bar stock segment is flattened using a mechanical forging press applying approximately 100 MPa (1,000 tons) of pressure. The flattened section of the bar stock is approximately 1.1 cm (7/16") thick and 3.2 cm (1~
wide. Thereafter, the bar stock segments are bent at the location of the flattened section to form the U-bolt product.
The flattening step provides elongation to the bar stock segment such that the total length of the finished U-bolt product is somewhat in excess of 90 cm (36"). The finished U-bolt product has the desired mechanical properties of tensile strength and yield strength originally possessed by the bar stock and therefore requires no further strengthening processing steps.
~ 9 Examples 2-6 Five high-strength cold drawn C-1541 steel bars having diameters of about 18.3 mm (O.72") were cut to lengths of approximately 46 cm (18'l). These bars were turned down to diameters of about 1.25 cm (0.5") and tested for mechanical properties reported in Table I. For instance, these bars had tensile strengths of about 960 MPa (140,000 psi) and yield strengths of about 900 MPa (130,000 psi) as set forth in Table I.
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- . -Examples 7-11 Five high-strength cold drawn C-1541 steel bars having diameters of about 18.3 mm (0.72") were cut to lengths of approximately 46.0 cm (18") from the same length of bar stock used to make bars of Examples 2-6. The bars were then heated to approximately 270~C (550~F) and a medial section of each bar was flattened in a fashion similar to Example 1 using a mechanical forging press applying approximately 100 MPa (1,000 tons) of pressure.
The flattened bars were then turned down to a diameter of about 1.25 cm (0.5") and tested for the properties listed in Table II.
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o r o~ r o ~ ~ r~ o~r ~D o ~ o 10 ~ ~ ~':J~ In O ~'J~ ~ N ~r ~ ~ ~ O
O ~1 0 ~ O~ ~ ~ ~7~ ~~ O ~1 ~ O
~11 ~ ~u~ o ~ ~1 ~ ~ O O O o r r o ~ o~ ~ o\o o\
O CO O ~ ~ O ~l ~ O ~ ~ ~D O r o ~ ~ ~ ~ u~ ~ ~l ~ o ~ ~ oo . . ~ o O ~1 0 ~ a~ ~ ~O al ~ o ol ~ ~ ~ o ~ ~~ o -11 ,1 ~ ,1 ~1 o o ~ ~ o o ~ r o o ~ ~ o\o o\o o r a~ ~ o o o ~ ~ o o~ ~ o r O ~1 0 ~~ r~ ~O cr~ ~ o H ~ ~-1 ~ O ~ ~1~Ç\ O
H o~¦ H ~1 ~1 ~_1 W
Co ~ ~ O O~ ooO O ~ U~ o\~ o\~ ~ ~ ~D
ro oo o ~
~r ~ ~ ~ ~ ~ ~ r ~ ~ C0 ~~ r o O ~ O ~ o~ ~~1 ~ O O ~1 ~ O
o ~ ~ ~D
~ ~ o o o u~o o o Ln ~ oo o\o o\
o c~ O a~ u~ ~r~ ~ ~ r ~ r o ~ o Ln ~ ~ ~ r ~r~ r ~ ~ ~ 0 ~ ~ ~r o O ~1 0 ~ a~ ~co ~ ~ ~r o a~ ,i ~ o ~ ~ ~ o ~ ~ ~ o c H
H O U~ t~ ~l X~ X ~--1 X ~ 4 X o\~ o\~ ~1 O
a~
s~
$~ a o o o c a o ~_~ o U
a) ~ ~ ~ u.
a ~ ~ ~ ~ a~ a ~ ~ C - ~
a) ~ a) c c o ~ ~
a) ~ aJ ~ a a) ~ _ 1 3 ~ r~
The finished bars of Table II had desired mechanical properties greater than those originally possessed by the bars of Table I. For example, the tensile strengths increased from about 960 MPa (140,000 psi) to about 1100 MPa (160,000 psi) and the yield strengths increased from about 890-905 MPa (130-132,000 psi) to about 1015-1025 MPa (148-150,000 psi).
Thus, the method provides for warm forming a blank into a part whereby the mechanical properties of tensile and yield strengths may be greater than the blank.
~ ~ oo r--o o co ooO O ~ ~ O~o o\~ c~
o r o~ r o ~ ~ r~ o~r ~D o ~ o 10 ~ ~ ~':J~ In O ~'J~ ~ N ~r ~ ~ ~ O
O ~1 0 ~ O~ ~ ~ ~7~ ~~ O ~1 ~ O
~11 ~ ~u~ o ~ ~1 ~ ~ O O O o r r o ~ o~ ~ o\o o\
O CO O ~ ~ O ~l ~ O ~ ~ ~D O r o ~ ~ ~ ~ u~ ~ ~l ~ o ~ ~ oo . . ~ o O ~1 0 ~ a~ ~ ~O al ~ o ol ~ ~ ~ o ~ ~~ o -11 ,1 ~ ,1 ~1 o o ~ ~ o o ~ r o o ~ ~ o\o o\o o r a~ ~ o o o ~ ~ o o~ ~ o r O ~1 0 ~~ r~ ~O cr~ ~ o H ~ ~-1 ~ O ~ ~1~Ç\ O
H o~¦ H ~1 ~1 ~_1 W
Co ~ ~ O O~ ooO O ~ U~ o\~ o\~ ~ ~ ~D
ro oo o ~
~r ~ ~ ~ ~ ~ ~ r ~ ~ C0 ~~ r o O ~ O ~ o~ ~~1 ~ O O ~1 ~ O
o ~ ~ ~D
~ ~ o o o u~o o o Ln ~ oo o\o o\
o c~ O a~ u~ ~r~ ~ ~ r ~ r o ~ o Ln ~ ~ ~ r ~r~ r ~ ~ ~ 0 ~ ~ ~r o O ~1 0 ~ a~ ~co ~ ~ ~r o a~ ,i ~ o ~ ~ ~ o ~ ~ ~ o c H
H O U~ t~ ~l X~ X ~--1 X ~ 4 X o\~ o\~ ~1 O
a~
s~
$~ a o o o c a o ~_~ o U
a) ~ ~ ~ u.
a ~ ~ ~ ~ a~ a ~ ~ C - ~
a) ~ a) c c o ~ ~
a) ~ aJ ~ a a) ~ _ 1 3 ~ r~
The finished bars of Table II had desired mechanical properties greater than those originally possessed by the bars of Table I. For example, the tensile strengths increased from about 960 MPa (140,000 psi) to about 1100 MPa (160,000 psi) and the yield strengths increased from about 890-905 MPa (130-132,000 psi) to about 1015-1025 MPa (148-150,000 psi).
Thus, the method provides for warm forming a blank into a part whereby the mechanical properties of tensile and yield strengths may be greater than the blank.
Claims (6)
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method of making a high-strength steel part comprising providing a blank of high-strength steel material having a tensile strength of at least 800 MPa (120,000 psi) and a yield strength of at least 600 MPa (90,000 psi) and warm forming the blank at a temperature between 150°C (300°F) to 650°C (1200°F) to provide a part having a predetermined geometric configuration, whereby the mechanical properties of tensile strength and yield strength of the part are greater than the blank and are produced without further strengthening processing steps, wherein the high-strength steel material comprises, by weight percent:
carbon 0.30 to 0.65%
manganese 0.30 to 2.5%
vanadium, wherein vanadium is present in an amount greater than zero, up to .35%
iron balance.
carbon 0.30 to 0.65%
manganese 0.30 to 2.5%
vanadium, wherein vanadium is present in an amount greater than zero, up to .35%
iron balance.
2. A method as claimed in claim 1, wherein the high-strength steel material has previously been hot reduced and cold drawn to provide the blank having a tensile strength of at least 800 MPa (120,000 psi) and a yield strength of at least 600 MPa (90,000 psi).
3. A method as claimed in either claim 1 or claim 2, wherein the blank of high-strength steel material has a tensile strength of at least 1025 MPa (150,000 psi) and a yield strength of at least 900 MPa (130,000 psi).
4. A method as claimed in claim 3, wherein the high-strength steel material has previously been hot reduced and in:
cold drawn to provide the blank with the said strength properties.
cold drawn to provide the blank with the said strength properties.
5. A method as claimed in any one of claims 1 to 4, wherein the high-strength steel material comprises, by weight percent:
carbon 0.50 to 0.55%
manganese 1.20 to 1.65%
vanadium 0.03 to 0.15%
iron balance.
carbon 0.50 to 0.55%
manganese 1.20 to 1.65%
vanadium 0.03 to 0.15%
iron balance.
6. A method as claimed in any one of claims 1 to 5, wherein the part is a bolt, screw, axle, sway bar or cam shaft.
in:
in:
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US82774092A | 1992-01-29 | 1992-01-29 | |
| US827,740 | 1992-01-29 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2128019A1 CA2128019A1 (en) | 1993-08-05 |
| CA2128019C true CA2128019C (en) | 1999-02-23 |
Family
ID=25250021
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002128019A Expired - Lifetime CA2128019C (en) | 1992-01-29 | 1993-01-21 | High-strength steel parts and method of making |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0624205A1 (en) |
| JP (1) | JP2878842B2 (en) |
| KR (1) | KR100230882B1 (en) |
| BR (1) | BR9305812A (en) |
| CA (1) | CA2128019C (en) |
| WO (1) | WO1993015233A1 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5454888A (en) * | 1990-10-24 | 1995-10-03 | Consolidated Metal Products, Inc. | Warm forming high-strength steel structural members |
| AU679106B2 (en) * | 1993-07-14 | 1997-06-19 | Consolidated Metal Products, Inc. | Warm forming high strength steel parts |
| US6852181B2 (en) * | 2001-10-23 | 2005-02-08 | Consolidated Metal Products, Inc. | Flattened U-bolt and method |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3001897A (en) * | 1956-10-22 | 1961-09-26 | Lasalle Steel Co | Steels and method of processing same |
| US3720087A (en) * | 1969-10-03 | 1973-03-13 | Lasalle Steel Co | Metallurgical process of bending steel to desired curvature or straightness while avoiding losses in strength |
| US3959999A (en) * | 1974-11-01 | 1976-06-01 | Ivan Konstantinovich Lyskov | Method of producing long-length articles from hot-rolled carbon steel and article produced thereby |
| US4289548A (en) * | 1977-08-19 | 1981-09-15 | Jones & Laughlin Steel Corporation | High strength cold finished bars |
| FR2525709B1 (en) * | 1982-04-22 | 1986-04-04 | Ugine Aciers | STEEL SCREWS AND BOLTS WITH HIGH MECHANICAL CHARACTERISTICS AND PROCESS FOR THE PREPARATION OF SUCH SCREWS AND BOLTS |
| US5094698A (en) * | 1990-10-24 | 1992-03-10 | Consolidated Metal Products, Inc. | Method of making high strength steel parts |
-
1993
- 1993-01-21 WO PCT/US1993/000519 patent/WO1993015233A1/en not_active Application Discontinuation
- 1993-01-21 BR BR9305812A patent/BR9305812A/en not_active IP Right Cessation
- 1993-01-21 JP JP5513314A patent/JP2878842B2/en not_active Expired - Lifetime
- 1993-01-21 CA CA002128019A patent/CA2128019C/en not_active Expired - Lifetime
- 1993-01-21 EP EP93904550A patent/EP0624205A1/en not_active Ceased
- 1993-01-21 KR KR1019940702598A patent/KR100230882B1/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| AU668542B2 (en) | 1996-05-09 |
| KR100230882B1 (en) | 1999-11-15 |
| BR9305812A (en) | 1997-02-18 |
| JPH07505188A (en) | 1995-06-08 |
| KR950700429A (en) | 1995-01-16 |
| EP0624205A1 (en) | 1994-11-17 |
| AU3587893A (en) | 1993-09-01 |
| JP2878842B2 (en) | 1999-04-05 |
| CA2128019A1 (en) | 1993-08-05 |
| WO1993015233A1 (en) | 1993-08-05 |
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