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Production method of rolled sheet for cold-rolling, and production method of pure titanium sheet

  • US 10,640,859 B2
  • Filed: 03/16/2016
  • Issued: 05/05/2020
  • Est. Priority Date: 03/25/2015
  • Status: Active Grant
First Claim
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1. A method for producing a rolled sheet for cold-rolling, the method consisting of:

  • hot-rolling a pure titanium material while coiling;

    annealing a hot-rolled sheet formed by the hot-rolling; and

    removing an oxidized layer formed on a surface of the hot-rolled sheet during the hot-rolling and the annealing,wherein;

    a coiling temperature in the hot-rolling is less than or equal to 500°

    C.;

    the annealing is performed by raising a temperature of the hot-rolled sheet formed by the hot-rolling to an elevated temperature T ranging from 650°

    C. to 750°

    C. and subsequently maintaining the hot-rolled sheet at the elevated temperature T for a duration t satisfying (2), (4), or (5) as follows, depending on the elevated temperature T;

    (2) 80 sec ≤

    t≤

    160 sec when 680°

    C. ≤

    T≤

    720°

    C.,(4) 160 sec <

    t≤

    200 sec when 650°

    C. ≤

    T<

    680°

    C., and(5) 40 sec ≤

    t<

    80 sec when 720°

    C. <

    T≤

    750°

    C.; and

    the annealing is controlled such that a percentage area of recrystallized grains in a microstructure of the hot-rolled sheet after the annealing is greater than or equal to 90%, and that a mean grain diameter of the recrystallized grains is greater than or equal to 6 μ

    m and less than or equal to 10 μ

    m.

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