Method for producing an no electric strip of intermediate thickness

Abstract

The present invention relates to a process for producing a non-oriented electrical steel strip, comprising at least the following process steps (A) provision of a hot-rolled, optionally separately heat-treated, non-oriented electrical steel strip, (B) cold rolling of the electrical steel strip from step (A) to a thickness of from 0.5 to 0.8 mm in order to obtain a first cold-rolled strip, (C) intermediate heat treatment of the first cold-rolled strip from step (B) at a temperature of from 700 to 1100° C. in order to obtain an intermediate-heat-treated, first cold-rolled strip, (D) cold rolling of the intermediate-heat-treated, first cold-rolled strip from step (C) to a thickness of from 0.24 to 0.36 mm in order to obtain a second cold-rolled strip and (E) final heat treatment of the second cold-rolled strip from step (D) at a temperature of from 900 to 1100° C. in order to obtain the non-oriented electrical steel strip, a non-oriented electrical steel strip obtained in such a way and the use thereof.

1 . A non-oriented electrical steel strip comprising the following composition and texture (all figures in % by weight)
 from 2.1 to 3.6 of Si,   from 0.3 to 1.2 of Al,   from 0.01 to 0.5 of Mn,   up to 0.05 of Cr,   up to 0.005 of Zr,   up to 0.04 of Ni,   up to 0.05 of Cu,   up to 0.005 of Cu,   up to 0.005 of at least one rare earth metal,   up to 0.005 of Co,   balance Fe and unavoidable impurities,   
       with
     I   ϵ,{554}<225>   −I   ζ,{110}<001> <3, 
 
       where
 I ϵ,{554}<225>  and I ζ,{110}<001>  have the following meanings: 
 I ϵ,{554}<225>  intensity I in the ϵ-fiber of the orientation density f(g) in Euler space at φ 1 =90°, φ 2 =45° and ϕ=60° and orientation {554}<225> and 
 I ζ,{110}<001>  intensity I of the orientation density f(g) in Euler space in the ζ-fiber at φ 1 =0°, φ 2 =0° and ϕ=45° and orientation {110}<001>. 
 
     
     
         2 . The non-oriented electrical steel strip as claimed in  claim 1 , wherein the non-oriented electrical steel strip has a final thickness of from 0.24 to 0.36 mm. 
     
     
         3 . The non-oriented electrical steel strip as claimed in  claim 2 , wherein the polarization J 2500/50  at 2500 A/m and 50 Hz and the magnetic loss P 1.5/50  at 1.5 T and 50 Hz satisfy the following relationships after the final heat treatment:
 for hot-rolled strip material which has not been bell heat treated: J 2500/50 >−0.045*P 15/50   2 +0.3*P 15/50 +1.085 (1)   for hot-rolled strip material which has been bell heat treated: J 2500/50 >−0.045*P 15/50   2 +0.28*P 15/50 +1.165 (2).   
     
     
         4 . A process for producing a non-oriented electrical steel strip as claimed in  claim 3  , comprising at least the following process steps:
 (A) provision of a hot-rolled, optionally separately heat-treated, non-oriented electrical steel strip, by a conventional manufacturing route via a continuous casting plant or by thin slab manufacture, in a thickness of from 1 to 4 mm, 
 (B) cold rolling of the electrical steel strip from step (A) to a thickness of from 0.5 to 0.8 mm in order to obtain a first cold-rolled strip, 
 (C) intermediate heat treatment of the first cold-rolled strip from step (B) at a temperature of from 700 to 1100° C. in order to obtain an intermediate-heat-treated, first cold-rolled strip, 
 (D) cold rolling of the intermediate-heat-treated, first cold-rolled strip from step (C) to a thickness of from 0.24 to 0.36 mm in order to obtain a second cold-rolled strip; and 
 (E) final heat treatment of the second cold-rolled strip from step (D) at a temperature of from 900 to 1100° C. in order to obtain the non-oriented electrical steel strip. 
 
     
     
         5 . The process as claimed in  claim 4 , wherein step (C) is carried out in one of a continuous furnace and as bell heat treatment. 
     
     
         6 . The process as claimed in  claim 5 , wherein the cold rolling in step (B) is carried out with a degree of cold rolling of from 30 to 90%. 
     
     
         7 . The process as claimed in  claim 6 , wherein the cold rolling in step (D) is carried out with a degree of cold rolling of from 30 to 90%. 
     
     
         8 . The process as claimed in  claim 7 , wherein a hot-rolled strip bell heat treatment is carried out at a maximum temperature of from 640 to 900° C. in step (A). 
     
     
         9 . A non-oriented electrical steel strip produced by the process as claimed in  claim 8 . 
     
     
         10 . An electric motor comprising:
 an iron core having the non-oriented electrical steel strip as claimed in  claim 3 .