US3877281A - Method for producing a high strength bolt - Google Patents

Method for producing a high strength bolt Download PDF

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Publication number
US3877281A
US3877281A US394134A US39413473A US3877281A US 3877281 A US3877281 A US 3877281A US 394134 A US394134 A US 394134A US 39413473 A US39413473 A US 39413473A US 3877281 A US3877281 A US 3877281A
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cooling
bolt
subjected
heating
percent
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Kiyoshi Shimizu
Toshihiro Minami
Eiji Niina
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Kobe Steel Ltd
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Kobe Steel Ltd
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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
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/06—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires

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  • ABSTRACT A method for producing a high strength bolt from a carbon steel or a low alloy steel material, which comprises the steps of subjecting said material, in turn, to cold working at the reduction-of-area percentage of 10 percent and over rapid heating to a temperature range from 450C to A transformation point, warmforming to a bolt shape and air-cooling or cooling at a cooling rate higher than that of the air-cooling.
  • the steel material adapted for use herein includes a steel having a pearlite structure or a tempered martensite structure, and particularly the steel having the latter structure presents excellent resistance to the delayed rupture phenomenon with an accompanied high tensile strength of over 100 kg/mm particularly, in the range from 130 to 140 kg/mm and over.
  • FIG. 1B MATERIAL SUBJECTED T0 43% WIRE- DRAWING (YP76.5 TS88.4 EL
  • FIG. 2 HEAD PORTION SHANK PORTION TEMPERATURE m WARMFORMING (c) FIG. 2
  • This invention relates to a method for producing a high strength bolt from a carbon steel or a low alloy steel material which has been subjected to hot-rolling, normalizing or annealing, thereby presenting a ferritepearlite structure or which has been subjected to hardening and tempering, thereby presenting a tempered martensite structure, and more particularly to a method which comprises the steps of subjecting said steel material, in turn, to cold working at a reductionof-area percentage of percent and over, rapid heating to a temperature range from 450 C to A transformation point, hot forming to a bolt shape and air cooling or cooling at a cooling rate higher than that of the air-cooling, thereby presenting a high strength bolt having a tensile strength of 70 kg/mm and over.
  • strengthening treatment as used herein is a combination of working and heat-treatment which includes a cycle
  • a method for producing a high strength bolt has recourse to the steps wherein, to form a bolt shape, a cold-or-hot-working or machining operation is used, followed by a refining treatment such as hardening and tempering, thus obtaining a desired strength and toughness.
  • a method for producing a high strength bolt from a carbon steel or low alloy steel material wherein, for the production of a high strength bolt having a tensile strength ranging from to kglmm a steel wire (rod) as rolled or as normalized and annealed is in turn subjected to cold working at a reduction-of-area percentage of 10 percent and over, heating at a heating rate of over 50C/min. to a temperature range from 450 C to A, transformation point by using heating means such as resistance heating under air, high frequency induction heating, flame heating, or the like, and then hot-forming to a bolt shape, followed by air cooling or cooling at a cooling rate higher than that of the air cooling.
  • heating means such as resistance heating under air, high frequency induction heating, flame heating, or the like
  • a carbon steel or low alloy steel material in a wire or rod form is subjected in turn to a refining treatment of hardening and tempering, cold working at a reduction-of-area percentage of 10 percent and over, heating at a heating rate of over 50 C/min. to a temperature range from 450 C to A transformation point by using the aforesaid heating means, Warm-forming to a bolt shape and finally air-cooling or cooling at a cooling rate higher than that of the air cooling.
  • the level of tensile strength referred to herein is not necessarily limited to that exceeding 110 kg/mm
  • a high strength bolt, which is made of carbon steel or low alloy steel material and which is produced according to the method of the present invention and has a tensile strength of over 110 kg/mm presents excellent resistance to the delayed rupture phenomenon due to a sudden occurrence of embrittlement, and particularly presents a bolt which has a tensile strength of a range from to kg/mm and over, affording excellent resistance to the delayed rupture pheonomenon, as compared with conventional bolts subjected to the refining treatment.
  • FIG. 1 is an electron-microscopic picture at 22,50OX, of the structure of a steel A as rolled and the structure of the steel A which has been subjected to 43 percent wire-drawing, followed by a strengthening treatment at 550C;
  • FIG. 2 is a plot showing the relationship of the temperature used in hot-forming a rolled steel A to a bolt shape versus the hardness of a bolt at bolt head and shank;
  • FIG. 3 is a diagram showing distribution of hardness at bolt head and shank, in connection to the bolt produced according to the present invention and the bolt produced according to the prior art (cold-forming);
  • FIG. 4 is a diagram showing distribution of hardness at bolt head and shank of a bolt produced from the refined steel C according to the present invention.
  • the types of steels applicable to the method of the present invention should preferably be carbon steels having a carbon content of no more than 0.5 percent and low alloy steels.
  • the reason why the content of carbon should be no more than 0.5 percent is as follows: Although a high strength bolt having a tensile strength of 100 to 120 kg/mm may be produced of rolled or tempered steels, the use of low and medium carbon steels rather than high carbon steels is best suited and advantageous for the method of the present invention using the strengthening treatment from the viewpoints of tensile strength and toughness. Carbon is an essential component for a material for use in producing a high strength bolt having a tensile strength of over 110 kg/mm for the purpose of applying a refining treatment of hardening and tempering as well as for achieving arequired hardenability and strength. However, from the viewpoint of the delayed rupture phenomenon, the content of the carbon should preferably be no more than 0.5 percent. Although the content of other elements to be added are not specifically limited, it is preferable that a small amount of elements such as Al, N, Ti, Nb, etc. may be added for achieving a finer grain size of austenite crystals.
  • the steel material of which the high strength bolt having a tensile strength of over 110 kg/mm is made, has a tempered martensite structure which has been subjected to hardening and annealing treatments.
  • the tempering to be used depends on desired strength and toughness of the steel, and the workability of the subsequent working steps of the steel material, and it should also be recognized that the hardening treatment is effective for achieving the desired resistance to the delayed rupture pheonomenon, if the grain size of the austenite crystals over ASTM No. is obtained by utilizing a rapid heating for achieving finer grain size, in addition to the ordinary heat-treatment.
  • the reason why the reduction-of-area percentage of the cold working should be over 10 percent is that an increase in strength of a bolt shank portion, which has been warm-worked, may be expected from a rapid heating by using air-atmosphere resistance-heating and high frequency induction heating during the warmworking, whereas the strength in the bolt head portion will be decreased due to the aforesaid warm-working.
  • the reduction-of-area percentage of 10 percent and over is required for achieving uniformity in the percent is difficult to apply to a martensite steel.
  • the reduction-of-area percentage of cold working of over 10 percent is suited for rolled steel material or normalized steel material, while the reductionof-area percentage of cold working of 10 percent to percent is suited for a hardened and tempered steel.
  • Cold working as used herein should preferably be cold drawing (wire drawing), but is not limited thereto.
  • the cold workingused may include roller-dies working.
  • the temperature as used for heating in the present invention should fall in a range from 450 C to A transformation point. This is because the heating temperature of a range from 449 C to 250 C tends to cause cracking in the head portion of a bolt, since the heating temperature is within the range of blue shortness temperatures, while heating temperatures of over the A, transformation point will lead to a poor strengthening effect.
  • Meant by the heating temperature is the temperature obtained by using electric-resistance heating means, high frequency induction heating means, etc.
  • the bolt may be rapidly heated in a salt bath, lead bath, air atmosphere furnace, or the like, which has been maintained at a temperature ranging from 450C to 700C, and soaked for no more than 5 minutes therein, followed by air cooling or cooling at a cooling rate higher than that of the air cooling, thereby achieving the desired strengthening effect.
  • the method of the present invention can obviate the use of heat treatment at an elevated temperature, such as hardening and tempering, after forming to a bolt shape as in the conventional method.
  • an elevated temperature such as hardening and tempering
  • the temperature for warm-forming or re-heating treatment is limited to 700C, which is much lower than the hardening temperatures, there can be achieved improvements in the skin condition as well as dimensional accuracy for the bolts, without incurring the possibility of oxidation or decarbonization, thereby enabling the production of consistent high quality bolts.
  • Table 1 shows the chemical composition of steel wires tested.
  • steels A and B represent the samples which were subjected in turn to cold wiredrawing at a reduction-of-area percentage of 5 to 43 percent, heating at a heating rate of 40C/sec. by using an electric heating means, warm-forming to M10 bolt (shank: 48 L) and water-quenching immediately thereafter.
  • the bolts thus produced were again placed in a salt bath which had been heated to a temperature of 550C and held therein for 20 seconds, followed by water quenching.
  • FIG. 1 shows the relationship of the mechanical properties and the electron-microscopic pictures of materials which are made of rolled steel of sample A and have been subjected to 43 percent cold wirepared with a cold worked steel.
  • the aforesaid fact is considered to have bearing on the increase in strength of bolts, because the shank portion of a bolt does not undergo the influence by hot-forming and hence retains improved properties given by the strengthening treatment of the present invention.
  • FIG. 2 shows the relationship of a warm-forming temperature versus hardness of head portions and shank portions of bolts which were produced by subjecting steel A, in turn, to cold wire-drawing at a reduction-ofarea of 20 percent, rapid heating at a heating rate of 40C/sec., and forming to M10 bolt, followed by water quenching.
  • FIG. 2 reveals that the relationship of the difference in reduction-of-area percentage is maintained in fact for the difference in hardness for the bolts which have been cold formed, because the head portion of a cold formed bolt has been subjected to cold working at about 75 percent reduction-of-area percentage, whereas the shank portion of the bolt has been subjected to cold wire drawing of only percent reduction-of-area percentage.
  • the head least difference in hardness between the shank and head portions of the bolt.
  • the cooling after warm-forming should terminate as rapidly as possible. In other words, if a bolt is slowly cooled, then the bolt will be annealed, thereby failing to present the tensile strength of over 80 kg/mm which is essential for the high strength bolt.
  • Table 4 shows the tensile test results of bolts which have been produced by heating the steel B to 550C at a heating rate of C/sec. and hot-forming the same to M10 bolt, and subjecting the bolt to three types of cooling, i.e., water-quenching, air-cooling and slow cooling. This test reveals that the slow cooling results in the failure to obtain a high strength bolt.
  • the hardness of the head portion of the bolt varies, to some extent, with the varying reduction-of-area percentage of cold-wiredrawing and compression percentage of the head portion of the bolt, while the hardness increases in temperature range from 200C to 300C with the increase in warm-forming temperatures, but decreases thereafter, showing a sharp decrease at 400C thus presenting the In such cooling, air cooling may be suitably used for a bolt of a small diameter, whereas a bolt of a great diameter should be subjected to oil cooling or water cooling.
  • the bolt After being subjected to the method for producing a high strength bolt according to the present invention, if a bolt is still short of the strength required, then the bolt may be re-heated to achieve the required strength.
  • a bolt For reheating, a bolt is placed in a salt bath or lead bath which has been heated to a temperature of 450C to 700C, then allowed to stand therein for 5 minutes,
  • the re-heating should be carried out at a high heating rate and thus the bolt should be directly charged into a heating bath.
  • the soaking temperature of the bolt should be limited to a range between 450C and 700C, because a temperature over 450C can avoid the blue shortness, while a temperature below 700C can prevent a decrease in strength. While the soaking time depends on the type of heating furnace, size of bolt, heating temperatures and the like, the shorter soaking time is preferable because of its greater effectiveness, and thus limited up to 5 minutes.
  • Table shows the relationship of the mechanical properties and soaking time when M bolt is reheated to 450C in an air atmosphere furnace, the M10 bolt being produced from a steel wire B according to the method of the invention.
  • cooling after re-heating treatment should be accelerated to a cooling rate higher than that of air cooling, because slow cooling results in an annealed bolt having a low strength, as in the case of hotforming.
  • the steel wires should include those as rolled or normalized, and the type of steel should cover carbon steel or low alloy steels which are generally used as materials for producing bolts.
  • the rolled steels of two types i.e., steel A and steel B, as shown in Table l, were cold-drawn'at a reductionof-area percentage of 5 to 20 percent, then heated at a heating rate of 40C/sec. in an electric furnace, warm-formed to M10 bolt and water-quenched immediately thereafter.
  • part of the bolts thus treated were directly charged into a salt bath which has been heated to 550C for re-heating treatment, allowed to stand therein for 20 seconds, and then water quenched.
  • Those M10 bolts thus prepared were subjected toa-tensile test using a wedge. The results thereof are shown in Tables 6 and 7.
  • the sample steel C was oil-hardened at 870C and Sample steel C was subjectedin turn to a refining subjected to a refining treatment of tempering at treatment of oil hardening at 870C, then tempering at 570C, thus attaining mechanical properties as a re- 570C, then: to the prelimiary cold working at a reducfined steel, as shown in Table 4. Thereafter, the steel tion-of-area percentageof 20 percent, heating to 550C C was subjected to preliminary cold wire drawing at a at a heating rate of 75C/min. in a direct electricreduction-of-area percentage of 20 percent, heated at current-flowing heating means placed immediately a heating rate of 5C/min. to 40C/sec.
  • the 10 wire should present forming, i.e., water quenching air cooling and slow properties the same as shown in Table 8, because the cooling, revealing that slow cooling does not give a high sample steel C was subjected, like a 10 steel wire to the strength.
  • Cooling Condition After Hot-Forming I And Mechanical Properties Type of Cooling Yield Tensile Elonga- Final Reduc- Steel Condition Point Strength tion tion-of-area (kg/mm (kglmm 4 A percentage(%) Water 94.3 110.0 19.8 67.5 S tCeel Quenching (Al Sl Air 1027 Cooling 84.0 100.0 21.5 68.9 Steel) Slow Cooling 71.4 85.4 23.5 77.5
  • the sample steel C was sub ected to a refining treatment of oil-hardening at 870C and then tempering at figiliiiigffigli 570C, then preliminary cold working at a reductionof-area percentage of 5 to 40 percent, then heating at gzf f' g f f g f 550C at a heating rate of C/sec., warm-forming to (kg/mum (kg/mm 4 A age 65 M10 bolt 5 seconds thereafter, and finally waterquenching.
  • Table 10 shows the influence of the prelimigg ffii 23:3 182:; 13:; 23:8 nary cold working on the mechanical properties ob- 180C/min. 88.3 102.0 20.0 68.5 tained.
  • the sample steel C was in turn subjected to a refining treatment of oil-hardening at 870C and then tempering at 570C, then preliminary cold working at a reduction-of-area percentage of 20 percent, heating to 550C at a heating rate of 75C/sec. in a direct current-flowing heating means positioned immediately ahead of a press forming machine, warm-forming to a M10 bolt 5 seconds thereafter, and then water-quenching.
  • the bolt head exhibits abnormally high hardness (strength) as compared with those of the shank portion, while the toughness thereof decreases accordthe present invention presents lowered hardness for the head portion, because, when warm-formed as shown in FIG. 2, the deformation resistance of the sample steel will decrease with the accompanied lesser workhardening, while the shank portion of the bolt presents a hardness increase due to the strengthening treatment of the invention, i.e., a cycle of the preliminary cold working at a reduction-of-area percentage of 20 percent, rapid heating used for warm-forming and rapid cooling thereafter, thereby lessening the difference in hardness between the head and shank portions of the bolt.
  • the strengthening treatment of the invention i.e., a cycle of the preliminary cold working at a reduction-of-area percentage of 20 percent, rapid heating used for warm-forming and rapid cooling thereafter, thereby lessening the difference in hardness between the head and shank portions of the bolt.
  • sample steels D (boron steel) and E (Cr-Mo steel) were subjected twice to a cycle of hardening treatment by a high-frequency heating means, then a tempering treatment in a head bath, preliminary cold working at a reduction-of-area percentage of 20 percent, heating to 550C at a heating rate of C/sec. and warm forming to M10 bolt.
  • M10 bolt was formed with a notch of 0.05R (stress concentration factor 6) and was subjected to a socalled loop type delayed rupture test in a highhumidity atmosphere, in which the bolt was immersed in a water bath, with the tension being applied thereto.
  • Table 11 shows the results of such a test.
  • a high strength bolt according to the present invention presents a high tensile strength of over kg/mm without impairing the toughness thereof, in contrast to the conventional heat-treated bolt.
  • the bolts produced according to the present invention can present excellent resistance'to delayed rupture, as compared with conventional high strength bolts.
  • Table 1 Results of the Delayed-Rupture Test Mechanical Properties Sample Steel Heat-treatment Yield Tensile Elonga- Final Reduc- Austenite Notch Rupture Point Strength tion tion-of-area Grain Size Strength Time (kglmm (kglmm *1 percentage *2 (kg/mm *3 (HV) D-O (compara- .Formed to a bolt tive material) and then heat- 130.8 141.3 17.6 55.2 7.0 208.5 50
  • the material thus treated was then subjected twice to a strengthening treatment consisting of cold working at a r'eduction-of-area percentage of 20 percent, heating to 500C at a heating rate of 240C/sec., holding at said temperature for 5 seconds, and water quenching.
  • a method as defined in claim l wherein said steel material is subjected at least once to a cycle of hotrolling, rapid heating and hardening, thereby rendering finer the austenite crystal grain size to over No. 10 and inclusive according to ASTM grain size, after which said material is subjected to a tempering treatment, thereby presenting a tempered martensite structure, and wherein the reduction-of-area percentage of cold working ranges from 10 to 40 percent.

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Cited By (27)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
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
US3967486A (en) * 1974-01-18 1976-07-06 Mitsubishi Jukogyo Kabushiki Kaisha Toughening roll die work method for metallic material
US4035858A (en) * 1976-03-08 1977-07-19 Dahl Norman C Process for the preuse work-hardening of bolts
US4450703A (en) * 1981-01-14 1984-05-29 Incom International Inc. Rod ends and blanks and method and apparatus for making same
US4563222A (en) * 1983-06-29 1986-01-07 Sugita Wire Mfg. Co., Ltd. High strength bolt and method of producing same
US4608851A (en) * 1984-03-23 1986-09-02 National Forge Co. Warm-working of austenitic stainless steel
US4830683A (en) * 1987-03-27 1989-05-16 Mre Corporation Apparatus for forming variable strength materials through rapid deformation and methods for use therein
US4874644A (en) * 1987-03-27 1989-10-17 Mre Corporation Variable strength materials formed through rapid deformation
US5094698A (en) * 1990-10-24 1992-03-10 Consolidated Metal Products, Inc. Method of making high strength steel parts
US5186688A (en) * 1991-07-26 1993-02-16 Hargo 300-Technology, Inc. Method of manufacturing austenitic stainless steel drill screws
US5236520A (en) * 1990-10-24 1993-08-17 Consolidated Metal Products, Inc. High strength steel sway bars and method of making
US5330594A (en) * 1990-10-24 1994-07-19 Consolidated Metal Products, Inc. Method of making cold formed high-strength steel parts
US5453139A (en) * 1990-10-24 1995-09-26 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
US5538566A (en) * 1990-10-24 1996-07-23 Consolidated Metal Products, Inc. Warm forming high strength steel parts
US5704998A (en) * 1990-10-24 1998-01-06 Consolidated Metal Products, Inc. Hot rolling high-strength steel structural members
US6213884B1 (en) * 1999-10-20 2001-04-10 Daimlerchrysler Corporation Case hardened self-drilling, self-tapping, self-piercing fasteners and process for making the same
US6325874B1 (en) 1999-12-03 2001-12-04 Consolidated Metal Products, Inc. Cold forming flat-rolled high-strength steel blanks into structural members
US20030066576A1 (en) * 2001-09-14 2003-04-10 Soon-Tae Ahn Quenched and tempered steel wire with excellent cold forging properties
US20030111143A1 (en) * 2001-10-23 2003-06-19 Consolidated Metal Products, Inc. Flattened U-bolt and method
US6928737B2 (en) * 1999-12-16 2005-08-16 Nsk Ltd. Wheel-support rolling bearing unit and a method manufacturing the same
US20080229893A1 (en) * 2007-03-23 2008-09-25 Dayton Progress Corporation Tools with a thermo-mechanically modified working region and methods of forming such tools
US20090229417A1 (en) * 2007-03-23 2009-09-17 Dayton Progress Corporation Methods of thermo-mechanically processing tool steel and tools made from thermo-mechanically processed tool steels
WO2010130738A1 (en) 2009-05-12 2010-11-18 Metagra Bergara, S.A. Method for manufacturing fixing members adapted for railway sleepers by cold forming
CN103212958A (zh) * 2013-05-10 2013-07-24 江苏永昊高强度螺栓有限公司 航空发动机用连接件的加工方法
WO2016011458A1 (en) * 2014-07-18 2016-01-21 Henry Obermeyer Water control gate anchoring system and method

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5752558Y2 (sh) * 1977-08-03 1982-11-15
JPS5514176A (en) * 1978-07-18 1980-01-31 Sumitomo Metal Ind Ltd Cold forming method of non-tempered high tension bolt

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US2637672A (en) * 1950-08-22 1953-05-05 Westinghouse Electric Corp Process of producing bolts
US3532560A (en) * 1963-04-18 1970-10-06 Kobe Steel Ltd Cold-working process
US3674570A (en) * 1970-02-11 1972-07-04 Fagersta Bruks Ab High-strength low alloy ferritic steel small-gauge wire

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US1554336A (en) * 1920-04-17 1925-09-22 Roy H Smith Metal article
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US3532560A (en) * 1963-04-18 1970-10-06 Kobe Steel Ltd Cold-working process
US3674570A (en) * 1970-02-11 1972-07-04 Fagersta Bruks Ab High-strength low alloy ferritic steel small-gauge wire

Cited By (37)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3967486A (en) * 1974-01-18 1976-07-06 Mitsubishi Jukogyo Kabushiki Kaisha Toughening roll die work method for metallic material
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
US4035858A (en) * 1976-03-08 1977-07-19 Dahl Norman C Process for the preuse work-hardening of bolts
US4078273A (en) * 1976-03-08 1978-03-14 Dahl Norman C Process for the preuse work-hardening of bolts
US4450703A (en) * 1981-01-14 1984-05-29 Incom International Inc. Rod ends and blanks and method and apparatus for making same
US4563222A (en) * 1983-06-29 1986-01-07 Sugita Wire Mfg. Co., Ltd. High strength bolt and method of producing same
US4608851A (en) * 1984-03-23 1986-09-02 National Forge Co. Warm-working of austenitic stainless steel
US4830683A (en) * 1987-03-27 1989-05-16 Mre Corporation Apparatus for forming variable strength materials through rapid deformation and methods for use therein
US4874644A (en) * 1987-03-27 1989-10-17 Mre Corporation Variable strength materials formed through rapid deformation
US5704998A (en) * 1990-10-24 1998-01-06 Consolidated Metal Products, Inc. Hot rolling high-strength steel structural members
US5496425A (en) * 1990-10-24 1996-03-05 Consolidated Metal Products, Inc. Cold formed high-strength steel structural members
US5236520A (en) * 1990-10-24 1993-08-17 Consolidated Metal Products, Inc. High strength steel sway bars and method of making
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
US5453139A (en) * 1990-10-24 1995-09-26 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
US5538566A (en) * 1990-10-24 1996-07-23 Consolidated Metal Products, Inc. Warm forming high strength steel parts
US5308286A (en) * 1991-07-26 1994-05-03 Hargro 300-Technology, Inc. Device for manufacturing austenitic stainless steel drill screws
US5186688A (en) * 1991-07-26 1993-02-16 Hargo 300-Technology, Inc. Method of manufacturing austenitic stainless steel drill screws
US6213884B1 (en) * 1999-10-20 2001-04-10 Daimlerchrysler Corporation Case hardened self-drilling, self-tapping, self-piercing fasteners and process for making the same
US6325874B1 (en) 1999-12-03 2001-12-04 Consolidated Metal Products, Inc. Cold forming flat-rolled high-strength steel blanks into structural members
US6928737B2 (en) * 1999-12-16 2005-08-16 Nsk Ltd. Wheel-support rolling bearing unit and a method manufacturing the same
US20030066576A1 (en) * 2001-09-14 2003-04-10 Soon-Tae Ahn Quenched and tempered steel wire with excellent cold forging properties
US6752880B2 (en) * 2001-09-14 2004-06-22 Samhwa Steel Co., Ltd. Quenched and tempered steel wire with excellent cold forging properties
US20040206426A1 (en) * 2001-09-14 2004-10-21 Samhwa Steel Co., Ltd. Quenched and tempered steel wire with excellent cold forging properties
US20030111143A1 (en) * 2001-10-23 2003-06-19 Consolidated Metal Products, Inc. Flattened U-bolt and method
US6852181B2 (en) 2001-10-23 2005-02-08 Consolidated Metal Products, Inc. Flattened U-bolt and method
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WO2016011458A1 (en) * 2014-07-18 2016-01-21 Henry Obermeyer Water control gate anchoring system and method
US9957681B2 (en) 2014-07-18 2018-05-01 Henry K. Obermeyer Water control gate anchoring system and method
US11186960B2 (en) 2014-07-18 2021-11-30 Henry K. Obermeyer Water control gate anchoring methods
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JPS4965317A (sh) 1974-06-25
JPS5317968B2 (sh) 1978-06-12

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