CA2166713C - Warm forming high strength steel parts - Google Patents
Warm forming high strength steel parts Download PDFInfo
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- CA2166713C CA2166713C CA002166713A CA2166713A CA2166713C CA 2166713 C CA2166713 C CA 2166713C CA 002166713 A CA002166713 A CA 002166713A CA 2166713 A CA2166713 A CA 2166713A CA 2166713 C CA2166713 C CA 2166713C
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- strength steel
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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
- 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
- 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
- C21D9/30—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for crankshafts; for camshafts
-
- 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
-
- 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
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/02—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for springs
-
- 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
- C21D9/28—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for plain shafts
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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)
- Valve-Gear Or Valve Arrangements (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 of 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
WARM FORMING HIGH STRENGTH STEEL PARTS
The present invention relates to a method of making high-strength steel parts and the parts produced thereby, and mare 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.
The present invention relates to a method of making high-strength steel parts and the parts produced thereby, and mare 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 1100°C (2000°F) and higher.
At these hot forging temperatures, substantial scale and decarburization of the steel 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 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.
At these hot forging temperatures, substantial scale and decarburization of the steel 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 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 5094698 describes a method of making high-strength steel parts from blanks of high-strength steel material having a tensile strength of at least 800 N/mm2 and a yield strength of at least 600 N/mmz. The blank is warm formed to provide a part of desired geometric configuration. The mechanical properties of the part are substantially the same as the blank without further strengthening processing steps. The high strength steel material comprises, by weight, 0.30 to 0.650 carbon, 0.30 to 2.50% manganese and up to 0.350 vanadium with the balance being iron.
A method of making a high-strength steel part, in accordance with the invention, comprises providing a blank of high-strength steel material having a tensile strength of at least 800 N/mm2 (120,000 psi) and a yield strength of at least 600 N/mm2 (90,000 psi) and warm forming the blank into a', part having a specific geometric configuration, whereby ~~e mechanical properties of tensile strength and yield strength of the part are substantially the same as or greater than the blank; wherein the high-strength steel material comprises; by weight percent:
carbon 0.30 to 0.65%
manganese 0.30 to 2.500 iron balance said part with said mechanical properties of tensile strength and yield strength produced without further - 5 _ 2166113 strengthening processing steps, characterised in that the steel material further comprises, as a compulsory component, up to 0.35% of aluminum and/or niobium and/or titanium either alone or in a mixture including vanadium.
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 N/mm2 (120,000 psi) and a yield strength of at least about 600 N/mmz (90,000 psi).
The method includes warm forming a blank of high-strength steel material whereby the mechanical properties of tensile 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 term "blank" as used herein has its usual meaning, i.e., a piece of metal to be warm formed into a finished part of desired geometric configuration.
Blanks include such pieces of metal as bar stock (i.e., a piece of steel long in proportion to its thickness or width). The specific parts and configurations into which the blank is warm formed include various types of headed and upset shanks, cam rollers, nuts, ball joint L
casings, torsion bars, axles, cam shafts, spline shafts, steering arms, sway bars, I-beams and other such parts according to this invention.
It is known to use aluminum, niobium, titanium and vanadium as grain refiners in the high temperature heat treatment of steel. An appropriate collective term therefor is accordingly "ferrous grain refiners" and this is employed herein.
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 headed and upset shanks, screws, bolts, cam rollers, nuts, ball joint casings, torsion bars, axles, cam shafts, spline shafts, steering arms, sway bars, I-beams and other such parts susceptible to forming by the warm forging or forming process disclosed herein.
In a preferred embodiment, the method of the present invention for making a high-strength steel part includes providing a blank of high-strength steel t material having a tensile strength of at least about 800 N/mm2 (120,000 psi), and preferably at least about 1000 N/mm2 (150,000 psi), and a yield strength of at least about 600 N/mm2 (90,000 psi), and preferably at least about 900 N/mm2 (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%
at least 1 ferrous grain refiner from the group consisting of aluminum, niobium and titanium and mixtures thereof alone or with vanadium, in an effective amount 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 0.40 to about 0.55%
manganese about 0.30 to about 2.5%
at least 1 ferrous grain refiner from the group consisting of aluminum, niobium and titanium and mixtures thereof alone or with vanadium, in an effective amount up to about 0.20%
iron balance In a still more preferred form, the high-strength steel material has the following composition, by weight percent:
carbon about 0.50 to about 0.550 manganese about 1.20 to about 1.65 at least 1 ferrous grain refiner from the group consisting to aluminum, niobium and titanium and mixtures thereof alone or with vanadium, in an effective amount of about 0.03 to about 0.20°s 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 150-650°C (300 to about 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 substantially the same as or 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 N/mm2 (120, 000 psi) and a yield strength of at least about 600 N/mm2 (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 to the present inventor. The '445 patent 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 100-150 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 example illustrates the practice of the present invention to produce an upset shank from high-strength steel bar stock produced in accordance with the method disclosed in U.S. Patent No. 3,904,445 described above. The term "upset shank" refers generally to such structure as wire, rod, bar stock, etc. which has some of its length, typically an end, deformed into some form of a head having a cross-sectional area larger than the cross-sectional area of the balance of its length.
EXAMPLE
High-strength steel billet equivalent to grade 8 strength steel, having a diameter of 1.25 cm ('-~") is cut to lengths of approximately 10 cm (4"). This stock has a tensile strength of at least about 1000 N/mm2 (150,000 psi) and a yield strength of at least 900 N/mm2 (130,000 psi) with a ferrite-fine pearlite microstructure and a fine grain structure. The head of the shank is warm formed by forging or heading, one or more times, one end of each bar stock segment with a shaped die using a mechanical forging press applying approximately 150 tons of pressure. The head of the resulting shank is approximately 1 cm (3/8") thick and 2 cm (3/4") wide.
The mechanical properties of tensile strength and yield strength of the finished headed shank part are substantially the same or greater than that originally possessed by the bar stock, and therefore, no further strengthening processing steps are required. The finished headed shank also has enough of the desired mechanical property of ductility originally possessed by the bar stock that the need for further processing steps to improve toughness can generally be eliminated. ...
However, for certain uses of the shank, a stress relieving step may be necessary. For example, in some applications it is not desirable for a shank to break under its head when pulled in tension. It is usually more desirable for the shank to be the weakest section of the part. In such instances, stress relieving improves the toughness of the part such that it breaks in its shank under tensile loading.
Thus, in accordance with other features of this invention, the method provides for warm forming a blank into a part whereby the mechanical properties of tensile and yield strengths may be substantially the same as or greater than the blank.
A method of making a high-strength steel part, in accordance with the invention, comprises providing a blank of high-strength steel material having a tensile strength of at least 800 N/mm2 (120,000 psi) and a yield strength of at least 600 N/mm2 (90,000 psi) and warm forming the blank into a', part having a specific geometric configuration, whereby ~~e mechanical properties of tensile strength and yield strength of the part are substantially the same as or greater than the blank; wherein the high-strength steel material comprises; by weight percent:
carbon 0.30 to 0.65%
manganese 0.30 to 2.500 iron balance said part with said mechanical properties of tensile strength and yield strength produced without further - 5 _ 2166113 strengthening processing steps, characterised in that the steel material further comprises, as a compulsory component, up to 0.35% of aluminum and/or niobium and/or titanium either alone or in a mixture including vanadium.
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 N/mm2 (120,000 psi) and a yield strength of at least about 600 N/mmz (90,000 psi).
The method includes warm forming a blank of high-strength steel material whereby the mechanical properties of tensile 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 term "blank" as used herein has its usual meaning, i.e., a piece of metal to be warm formed into a finished part of desired geometric configuration.
Blanks include such pieces of metal as bar stock (i.e., a piece of steel long in proportion to its thickness or width). The specific parts and configurations into which the blank is warm formed include various types of headed and upset shanks, cam rollers, nuts, ball joint L
casings, torsion bars, axles, cam shafts, spline shafts, steering arms, sway bars, I-beams and other such parts according to this invention.
It is known to use aluminum, niobium, titanium and vanadium as grain refiners in the high temperature heat treatment of steel. An appropriate collective term therefor is accordingly "ferrous grain refiners" and this is employed herein.
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 headed and upset shanks, screws, bolts, cam rollers, nuts, ball joint casings, torsion bars, axles, cam shafts, spline shafts, steering arms, sway bars, I-beams and other such parts susceptible to forming by the warm forging or forming process disclosed herein.
In a preferred embodiment, the method of the present invention for making a high-strength steel part includes providing a blank of high-strength steel t material having a tensile strength of at least about 800 N/mm2 (120,000 psi), and preferably at least about 1000 N/mm2 (150,000 psi), and a yield strength of at least about 600 N/mm2 (90,000 psi), and preferably at least about 900 N/mm2 (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%
at least 1 ferrous grain refiner from the group consisting of aluminum, niobium and titanium and mixtures thereof alone or with vanadium, in an effective amount 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 0.40 to about 0.55%
manganese about 0.30 to about 2.5%
at least 1 ferrous grain refiner from the group consisting of aluminum, niobium and titanium and mixtures thereof alone or with vanadium, in an effective amount up to about 0.20%
iron balance In a still more preferred form, the high-strength steel material has the following composition, by weight percent:
carbon about 0.50 to about 0.550 manganese about 1.20 to about 1.65 at least 1 ferrous grain refiner from the group consisting to aluminum, niobium and titanium and mixtures thereof alone or with vanadium, in an effective amount of about 0.03 to about 0.20°s 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 150-650°C (300 to about 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 substantially the same as or 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 N/mm2 (120, 000 psi) and a yield strength of at least about 600 N/mm2 (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 to the present inventor. The '445 patent 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 100-150 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 example illustrates the practice of the present invention to produce an upset shank from high-strength steel bar stock produced in accordance with the method disclosed in U.S. Patent No. 3,904,445 described above. The term "upset shank" refers generally to such structure as wire, rod, bar stock, etc. which has some of its length, typically an end, deformed into some form of a head having a cross-sectional area larger than the cross-sectional area of the balance of its length.
EXAMPLE
High-strength steel billet equivalent to grade 8 strength steel, having a diameter of 1.25 cm ('-~") is cut to lengths of approximately 10 cm (4"). This stock has a tensile strength of at least about 1000 N/mm2 (150,000 psi) and a yield strength of at least 900 N/mm2 (130,000 psi) with a ferrite-fine pearlite microstructure and a fine grain structure. The head of the shank is warm formed by forging or heading, one or more times, one end of each bar stock segment with a shaped die using a mechanical forging press applying approximately 150 tons of pressure. The head of the resulting shank is approximately 1 cm (3/8") thick and 2 cm (3/4") wide.
The mechanical properties of tensile strength and yield strength of the finished headed shank part are substantially the same or greater than that originally possessed by the bar stock, and therefore, no further strengthening processing steps are required. The finished headed shank also has enough of the desired mechanical property of ductility originally possessed by the bar stock that the need for further processing steps to improve toughness can generally be eliminated. ...
However, for certain uses of the shank, a stress relieving step may be necessary. For example, in some applications it is not desirable for a shank to break under its head when pulled in tension. It is usually more desirable for the shank to be the weakest section of the part. In such instances, stress relieving improves the toughness of the part such that it breaks in its shank under tensile loading.
Thus, in accordance with other features of this invention, the method provides for warm forming a blank into a part whereby the mechanical properties of tensile and yield strengths may be substantially the same as or greater than the blank.
Claims (6)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method of making a high-strength steel part comprising the steps of:
providing a blank of high-strength steel material having a tensile strength of at least 800 N/mm2 (120,000 psi) and a yield strength of at least 600 N/mm2 (90,000 psi) and warm forming the blank at a temperature between 150-650°C(300-1200°F)into a part having a specific 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%
iron balance said part with said mechanical properties of tensile strength and yield strength produced without further strengthening processing steps, characterised in that the steel material further comprises, as a compulsory component, up to 0.35% of aluminum and/or niobium and/or titanium either alone or in a mixture including vanadium.
providing a blank of high-strength steel material having a tensile strength of at least 800 N/mm2 (120,000 psi) and a yield strength of at least 600 N/mm2 (90,000 psi) and warm forming the blank at a temperature between 150-650°C(300-1200°F)into a part having a specific 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%
iron balance said part with said mechanical properties of tensile strength and yield strength produced without further strengthening processing steps, characterised in that the steel material further comprises, as a compulsory component, up to 0.35% of aluminum and/or niobium and/or titanium either alone or in a mixture including vanadium.
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.
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 1000 N/mm2 (150,000 psi) and a yield strength of at least 900 N/mm2 (130,000 psi).
4. A method as claimed in any one of Claims 1 to 3, wherein the high-strength steel material comprises, by weight percent:
carbon 0.40 to 0.55%
manganese 0.30 to 2.50%
aluminum and/or niobium and/or titanium and mixtures thereof alone or with vanadium up to 0.20%
iron balance
carbon 0.40 to 0.55%
manganese 0.30 to 2.50%
aluminum and/or niobium and/or titanium and mixtures thereof alone or with vanadium up to 0.20%
iron balance
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%
aluminum and/or niobium and/or titanium and mixtures thereof alone or with vanadium 0.03 to 0.20%
iron balance
carbon 0.50 to 0.55%
manganese 1.20 to 1.65%
aluminum and/or niobium and/or titanium and mixtures thereof alone or with vanadium 0.03 to 0.20%
iron balance
6. A method as claimed in any one of Claims 1 to 5, wherein the part is selected from the group of parts consisting of various types of headed and upset shanks, bolts, screws, cam rollers, nuts, ball joint casings, torsion bars, axles, cam shafts, spline shafts, steering arms, sway bars and I-beams.
Applications Claiming Priority (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US9164093A | 1993-07-14 | 1993-07-14 | |
| US26841194A | 1994-07-08 | 1994-07-08 | |
| US268,411 | 1994-07-08 | ||
| US091,640 | 1994-07-08 | ||
| PCT/US1994/007239 WO1995002705A1 (en) | 1993-07-14 | 1994-07-11 | Warm forming high strength steel parts |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2166713A1 CA2166713A1 (en) | 1995-01-26 |
| CA2166713C true CA2166713C (en) | 2002-03-26 |
Family
ID=26784179
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002166713A Expired - Lifetime CA2166713C (en) | 1993-07-14 | 1994-07-11 | Warm forming high strength steel parts |
Country Status (7)
| Country | Link |
|---|---|
| EP (1) | EP0708842A1 (en) |
| JP (1) | JP3021658B2 (en) |
| KR (1) | KR960704072A (en) |
| AU (1) | AU679106B2 (en) |
| BR (1) | BR9407195A (en) |
| CA (1) | CA2166713C (en) |
| WO (1) | WO1995002705A1 (en) |
Families Citing this family (1)
| 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 |
Family Cites Families (11)
| 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 |
| 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 |
| JPS51144328A (en) * | 1975-06-06 | 1976-12-11 | Kobe Steel Ltd | Process for producing high tensile strength bolts with high yield rati o |
| 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 |
| DE3434743A1 (en) * | 1984-09-21 | 1986-04-03 | M.A.N.-B & W Diesel GmbH, 8900 Augsburg | Process for producing bar-shaped machine components |
| US5094698A (en) * | 1990-10-24 | 1992-03-10 | Consolidated Metal Products, Inc. | Method of making high strength steel parts |
| US5330594A (en) * | 1990-10-24 | 1994-07-19 | Consolidated Metal Products, Inc. | Method of making cold formed high-strength steel parts |
| US5454888A (en) * | 1990-10-24 | 1995-10-03 | Consolidated Metal Products, Inc. | Warm forming high-strength steel structural members |
| US5496425A (en) * | 1990-10-24 | 1996-03-05 | Consolidated Metal Products, Inc. | Cold formed high-strength steel structural members |
| WO1993015233A1 (en) * | 1992-01-29 | 1993-08-05 | Consolidated Metal Products, Inc. | High-strength steel parts and method of making |
-
1994
- 1994-07-11 AU AU75127/94A patent/AU679106B2/en not_active Ceased
- 1994-07-11 JP JP7504573A patent/JP3021658B2/en not_active Expired - Fee Related
- 1994-07-11 EP EP94925086A patent/EP0708842A1/en not_active Withdrawn
- 1994-07-11 WO PCT/US1994/007239 patent/WO1995002705A1/en not_active Application Discontinuation
- 1994-07-11 KR KR1019960700158A patent/KR960704072A/en not_active Application Discontinuation
- 1994-07-11 CA CA002166713A patent/CA2166713C/en not_active Expired - Lifetime
- 1994-07-11 BR BR9407195A patent/BR9407195A/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| WO1995002705A1 (en) | 1995-01-26 |
| KR960704072A (en) | 1996-08-31 |
| CA2166713A1 (en) | 1995-01-26 |
| BR9407195A (en) | 1996-09-17 |
| AU7512794A (en) | 1995-02-13 |
| AU679106B2 (en) | 1997-06-19 |
| JPH09500176A (en) | 1997-01-07 |
| EP0708842A1 (en) | 1996-05-01 |
| JP3021658B2 (en) | 2000-03-15 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKEX | Expiry |
Effective date: 20140711 |