Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
• • 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
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/004—Very low carbon steels, i.e. having a carbon content of less than 0,01%
• • 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
  • C21D2211/004—Dispersions; Precipitations
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P10/00—Technologies related to metal processing
  • Y02P10/20—Recycling

Definitions

• the invention relates to a hot-rolled strip or sheet of steel that can be enamelled on both sides, in particular IF steel (Interstitial Free).
• a high fish scale resistance of the enamelled strip or sheet is of particular importance.
• Fish scales mean flaws in the enamel, which means that continuous protection of the steel substrate is no longer guaranteed.
• the reaction of the water with the steel surface forms atomic hydrogen, which diffuses into the steel during the baking process.
• these steels are largely designed as IF steels and are based on alloy concepts in which the fish scale resistance is caused by cementite precipitates (hydrogen traps) smashed during cold rolling at the grain boundaries to which the atomic hydrogen attaches and thus becomes harmless with regard to fish scale formation ,
• Hot-rolled sheets enamelled on both sides are particularly susceptible to formation of fish scales, since both sheet sides are sealed after the enamel has solidified, thus preventing the free hydrogen diffusion from the steel.
• good fish scale resistance is combined with the low hydrogen solubility in ⁇ -iron, the hydrogen diffusion and the enamel adhesion.
• the fish scale risk is reduced if the capacity for hydrogen absorption in the steel substrate can be increased during the enamel penetration. This is the case when there is a sufficient number of hydrogen traps in the steel.
• this steel grade was combined with a rolling technology, which is characterized by heating the slab to 1100 - 1300 ° C and a final roll temperature of 900 ° O.
• the object of the invention is to provide a hot-rolled strip or sheet of steel, in particular IF steel, which can be enamelled on both sides and is resistant to fish scales, and a method for its production, with which the fish scale resistance can also be ensured when hot-rolling in the ferrite area.
• Ti, Nb and B are added in such an amount that, in addition to S and N, C is also completely hardened and a free residual content of Ti or Nb remains, which gives the steel an IF character.
• the free residual content of Ti or Nb of the steel with an IF character is at least 0.02%.
• the hot strip is pickled before enamelling.
• the pickling removal on the steel surface is dependent u. a. the Cu / P ratio of the steel to be pickled.
• N AI B Ti Nb 0 1 0.0020 0.30 0.007 0.003 0.011 0.0025 0.039 0.0002 0.047 0.002 - 2 0.0019 0.37 0.008 0.002 0.011 0.0020 0.034 ⁇ 0 .0001 0.035 0.029 - 3 0.0021 0.24 0.008 0.027 0.010 0.0008 0.019 ⁇ 0.0001 0.077 0.026 - 4 0.0062 0.25 0.014 0.001 0.012 0.0057 0.048 0.0065 ⁇ 0.001 0.033 - 5 0, 0041 0.26 0.009 0.040 0.011 0.0074 0.040 0.0081 0.049 0.032 6 0.0045 0.27 0.007 0.004 0.011 0.0063 0.002 0.0117 ⁇ 0.001 0.029 0.0153 7 0.0036 0.32 0.009 0.017 0.012 0 , 0018 0.065 ⁇ 0.0001 0.076 0.001 - * addition
• the steels were first rolled austenitically with a rolling start temperature of 1200 ° C, a final rolling temperature of 910 ° C and a coiling temperature of 720 ° C and then pickled.
• the fish scale resistance was determined on standard samples measuring 100 mm x 100 mm using the test email Ferro 2290, the test panels being enamelled on both sides. In these investigations, only the steel 5 showed no fish scales even after a long aging period of more than one year.
• the same steel 5 was then ferritically rolled with a rolling start temperature of 1050 ° C. or 1150 ° C., a final rolling temperature of 780 ° C. and a coiling temperature of 720 ° C. and then pickled.
• the fish scale resistance of the steel according to the invention thus results from the combination of the heterogeneous precipitates of nitrides, carbonitrides, carbosulfides, etc. produced in the structure, these precipitates on the one hand being sufficient in terms of arrangement and form to ensure fish scale resistance, but on the other hand are not essential Deterioration of the forming properties.
• the combined addition of S and N according to the invention and the microalloying elements Ti, Nb and B means that the fish scale resistance can not only be used for IF steels.
• a further advantage over the known hot-rolled steel is that it eliminates the need for additional cold rolling of the hot-rolled strip, which has the disadvantages mentioned.
• the steel In the case of final rolling in the austenite area, the steel is first cast into slabs in continuous casting and then split up into individual sections and after heating Temperatures> 1200 ° C hot-rolled into strips or sheets. At final rolling temperatures above the A 3 conversion temperature, it has proven advantageous for the formation of further heterogeneous precipitates of Nb carbide to maintain a reel temperature above 630 ° C. with subsequent cooling in air.
• the steel is first cast into slabs in continuous casting and, after being divided into individual sections and after being heated to temperatures> 1050 ° C, hot-rolled into strips or sheets.
• a reel temperature above 630 ° C. is also maintained to form Nb carbide, followed by cooling in air.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Heat Treatment Of Sheet Steel (AREA)
• Metal Rolling (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

Family

ID=34112154

Family Applications (1)

Country Status (5)

Cited By (2)

Families Citing this family (2)

Citations (6)

Family Cites Families (6)

• 2003
  • 2003-10-16 DE DE2003149364 patent/DE10349364B3/de not_active Expired - Fee Related
• 2004
  • 2004-06-10 UA UAA200605276A patent/UA79406C2/uk unknown
  • 2004-10-06 WO PCT/DE2004/002256 patent/WO2005040442A1/de active Search and Examination
  • 2004-10-06 EP EP04789962A patent/EP1673485A1/de not_active Withdrawn
  • 2004-10-06 RU RU2006116578A patent/RU2336314C2/ru not_active IP Right Cessation

Patent Citations (6)

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events