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
  • C21D6/00—Heat treatment of ferrous alloys
  • C21D6/02—Hardening by precipitation
• • 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
  • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
  • C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
  • C21D8/0263—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following hot rolling
• • 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
  • C21D2261/00—Machining or cutting being involved
• • 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
  • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
  • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
  • C21D8/0226—Hot rolling

Definitions

• the invention relates to a method according to the preamble of claim 1.
• the aim is the use of profiles with high strength characteristics as supplied for use as structural parts when high B auteilfesttechniken are to be achieved at low weights, for example for vehicle parts, hydraulic cylinder, steel high parts or when high loads are inevitably in the structural limitation of the dimensions as eg for oil field pipes for drilling technology.
• the pipes In practice, these conditions have limited the yield strength of the profiles to about 5oo N / mm2 and the tensile strength to about 65o N / mm2 when manufacturing, for example, welded pipes. Accordingly, the pipes must be formed from strips or sheets of soft grades with a yield strength of up to 5oo N / mm2, welded and, if the demands on the yield strength are higher, liquid-hardened and tempered, ie tempered.
• the invention has for its object to provide a method of the type mentioned, by means of which the disadvantages of the known methods avoided and in a relatively simple and therefore cost-effective manner while avoiding expensive remuneration a manufacture of high-strength profiles, in particular closed tube profiles with a yield strength of more than 5 0 o N / mm2, a tensile strength of more than 6 00 N / mm and high toughness, including the required mechanical welding.
• a precipitation-hardenable fine-grain steel is preferably understood to mean a steel which has a composition of Remainder has iron and usual impurities and - which in the finished state has an ASTM grain size of finer 6.
• the überalternde artificial aging of the precipitation hardenable fine-grain steel is done in which no grain refinement during cooling, preferably made of the above the A 1 temperature at 85o to 75 0 ° C to a collar gehaspelten steel strip.
• a corresponding microstructure is achieved according to the invention in sheet metal by furnace cooling, by means of which radiation and convection are prevented, from the rolling heat. Both with the rolled steel strip As with steel sheet, it is essential that the slowed down cooling is carried out up to a temperature of 400 ° C., while the subsequent cooling down to room temperature is carried out in any way.
• An open profile produced cold in this way is preferably welded to a closed tubular profile before further treatment according to the invention.
• the open or closed profiles produced according to the invention are subsequently subjected to a solution annealing above the A C3 temperature with subsequent cooling in order to bring about precipitation hardening, which is also referred to as particle hardening and fine grain hardening.
• the type of cooling should be used to achieve the formation of finely divided carbides, nitrides and carbonitrides with simultaneous fine grain formation.
• the temperature of the solution heat treatment is advantageously selected to be the temperature at which the stretch reduction of the starting pipe is started, ie the piercing temperature. A separate solution annealing is then no longer required in these reduced-stretch pipes, since the cooling following the solution annealing takes place during the reduction in stretch or immediately afterwards.
• Balance iron and unavoidable impurities after hot rolling the band preferably W armbreitband without intermediate cooling after the last W alzstich at a temperature of about 750 ° C into a coil (coil) is coiled and cooled in still air to 400 ° C.
• the natural heat storage capacity of the Federal is used for the armauslagern überalternde W, in which the precipitation and coagulation of the carbides, nitrides and carbonitrides largely proceed to completion while avoiding a grain refinement. Further cooling to room temperature is done in any way.
• the hot broadband has a yield strength of 455 N / mm 2 and a tensile strength of 65o N / mm 2 after it has completely cooled to room temperature or has aged.
• the hot wide strip is then cut into strips, if necessary trimmed and subsequently cold-formed, in the present example in a continuous process formed into a slotted tube, which is welded to a tube with a diameter of 159 mm by means of a high-frequency welding device.
• This tube is heated to a temperature of about 1 0 3 0 ° C and with this temperature as the piercing temperature in a stretch reduction process to the ge desired diameter of 6 0 , 3 mm rolled.
• the finished tube is cooled on a cooling bed in still air to room temperature.
• the coarse carbides, nitrides and carbonitrides are dissolved in the steel while the tube is being heated or held to the rolling temperature and are finely distributed during cooling or after the rolling with simultaneous formation of fine grains.
• the finished tube has after this treatment, a yield strength of 648 N / mm 2 and a Z ug strength of 845 N / mm to 2.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Thermal Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Mechanical Engineering (AREA)
• Physics & Mathematics (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Heat Treatment Of Steel (AREA)
• Heat Treatment Of Sheet Steel (AREA)
• Diaphragms For Electromechanical Transducers (AREA)
• Forging (AREA)
• Electrochromic Elements, Electrophoresis, Or Variable Reflection Or Absorption Elements (AREA)
• Heat Treatment Of Strip Materials And Filament Materials (AREA)

Applications Claiming Priority (2)

Publications (2)

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ID=6059969

Family Applications (1)

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Cited By (1)

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Citations (11)

Family Cites Families (16)

• 1979
  • 1979-01-02 DE DE2900022A patent/DE2900022C3/de not_active Expired
  • 1979-12-01 EP EP79104823A patent/EP0013331B1/fr not_active Expired
  • 1979-12-03 GR GR60667A patent/GR66519B/el unknown
  • 1979-12-26 SU SU792858051A patent/SU1087078A3/ru active
  • 1979-12-26 US US06/106,548 patent/US4414042A/en not_active Expired - Lifetime
  • 1979-12-27 RO RO7999732A patent/RO80871A/fr unknown
  • 1979-12-27 CA CA342,651A patent/CA1125150A/fr not_active Expired
  • 1979-12-27 JP JP16953379A patent/JPS5591941A/ja active Pending
  • 1979-12-28 NO NO794340A patent/NO151295C/no unknown
  • 1979-12-31 ES ES487392A patent/ES487392A1/es not_active Expired
• 1980
  • 1980-01-02 MX MX180650A patent/MX152698A/es unknown
• 1984
  • 1984-01-30 US US06/499,995 patent/US4732623A/en not_active Expired - Fee Related

Patent Citations (11)

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