Molybdenum material

Abstract

Provided is an industrially advantageous molybdenum material which is capable of causing secondary recrystallization to occur at a temperature lower than conventional and which, after the secondary recrystallization, can have a structure that comprises giant crystal grains with less grain boundaries and thus is excellent in creep resistance. The molybdenum material has, in at least a part thereof, a portion having a region where the peak intensities of the ( 110 ) and ( 220 ) diffraction planes are each less than the peak intensity of the ( 211 ) diffraction plane, as measured by X-ray diffraction, in a region at a depth of one-fifth of the entire thickness in a plate thickness direction from a surface.

1 . A molybdenum material having, in at least a part thereof, a portion having a region where peak intensities of (110) and (220) diffraction planes are each less than a peak intensity of a (211) diffraction plane, as measured by X-ray diffraction, in a region at a depth of one-fifth of an entire thickness in a thickness direction from a surface. 
     
     
         2 . The molybdenum material according to  claim 1 , wherein the molybdenum content is 98.0 mass % or more. 
     
     
         3 . The molybdenum material according to  claim 1 , having a shape of a plate member and having, in at least a part thereof, a portion having a region where peak intensities of (110) and (220) diffraction planes are each less than a peak intensity of a (211) diffraction plane, as measured by X-ray diffraction, in a region at a depth of one-fifth of a plate thickness in a plate thickness direction from at least one of upper and lower surfaces, facing each other, of the plate member. 
     
     
         4 . The molybdenum material according to  claim 1 , having a shape of a linear rod and having, in at least a part thereof, a portion having a region where peak intensities of (110) and (220) diffraction planes are each less than a peak intensity of a (211) diffraction plane, as measured by X-ray diffraction, in a region at a depth of one-fifth of a diameter toward a central axis from a surface. 
     
     
         5 . The molybdenum material according to  claim 1 , wherein an average grain size in a cross-section by a linear analysis method becomes 15 mm or more when heat-treated at 1700° C. or more. 
     
     
         6 . A molybdenum material being obtained by heat-treating the molybdenum material according to  claim 1  at 1700° C. or more, wherein the average grain size in a cross-section by a linear analysis method is 15 mm or more. 
     
     
         7 . A heating furnace structural member comprising the molybdenum material according to  claim 1 . 
     
     
         8 . A firing floor plate comprising the molybdenum material according to  claim 3 .