Method of producing a CoFe alloy strip

A method of producing a CoFe alloy strip, comprising:

• hot rolling a CoFe alloy to form a hot rolled strip, followed by quenching the strip from a temperature above 700° C. to a temperature of 200° C., wherein the CoFe alloy consists essentially of 35 wt %≤Co≤55 wt %, 0 wt %≤V≤3 wt %, 0 wt %≤Ni≤2 wt %, 0 wt % Nb≤0.50 wt %, 0 wt %≤Zr+Ta≤1.5 wt %, 0 wt %≤Cr≤3 wt %, 0 wt %≤Si≤3 wt %, 0 wt %≤Al≤1 wt %, 0 wt %≤Mn≤1 wt %, 0 wt %≤B≤0.25 wt %, 0 wt %≤C≤0.1 wt %, with the remainder being Fe as well as up to 1 wt % of impurities, wherein the impurities may comprises one or more elements from the group consisting of O, N, S, P, Ce, Ti, Mg, Be, Cu, Mo, W and up to 0.2 wt % of other impurities, and the CoFe alloy comprises an order/disorder temperature To/d and a ferritic/austenitic transformation temperature Tα/γ, wherein Tα/γ>To/d,
• cold rolling the quenched hot rolled strip,
• wherein after cold rolling, the strip comprises a disordered CoFe alloy phase with a bcc crystal structure and a Vickers Hardness HV of at least 320, and wherein the cold rolled strip has a thickness which is less than 0.50 mm after the cold rolling step,
• after cold rolling, continuous annealing the strip at a maximum temperature T1, wherein T1 is less than the order/disorder temperature To/d and 660° C.<T1<700° C., followed by cooling at a cooling rate R1 of at least 1 K/s in the temperature range of T1 to 500° C., wherein after continuous annealing, the strip comprises a partially ordered CoFe alloy phase with a B2 superstructure and a Vickers Hardness HV of at least 300, and
• after continuous annealing, annealing the strip at a temperature between 730° C. and Tα/γ, wherein after annealing, the strip or a part manufactured from the strip comprises an ordered CoFe alloy phase with a B2 superstructure and a Vickers Hardness HV of at most 300, and where the dimensional change in any lateral direction upon this annealing is less than 0.08%, if compared to the strip having the partially ordered CoFe alloy phase before the annealing.

A method of producing a CoFe alloy strip, comprising:

• hot rolling a CoFe alloy to form a hot rolled strip, followed by quenching the strip from a temperature above 700° C. to a temperature of 200° C., wherein the CoFe alloy consists essentially of 35 wt %≤Co≤55 wt %, 0 wt %≤V≤3 wt %, 0 wt %≤Ni≤2 wt %, 0 wt %≤Nb≤0.50 wt %, 0 wt %≤Zr+Ta≤1.5 wt %, 0 wt %≤Cr≤3 wt %, 0 wt %≤Si≤3 wt %, 0 wt %≤Al≤1 wt %, 0 wt %≤Mn≤1 wt %, 0 wt %≤B≤0.25 wt %, 0 wt %≤C≤0.1 wt %, with the remainder being Fe as well as up to 1 wt % of impurities, wherein the impurities may comprise one or more elements from the group consisting of O, N, S, P, Ce, Ti, Mg, Be, Cu, Mo, W and up to 0.2 wt % of other impurities, and the CoFe alloy comprises an order/disorder temperature To/d and a ferritic/austenitic transformation temperature Tα/γ, wherein Tα/γ>To/d,
• cold rolling the quenched hot rolled strip, the strip having a thickness of less than 0.50 mm after the cold rolling step,
• after cold rolling, continuous annealing the strip at a maximum temperature Ti, wherein T1 is less than the order/disorder temperature To/d and 660° C.<T1<700° C., followed by cooling at a cooling rate R1 of at least 1 K/s in the temperature range of T1 to 500° C.,
• forming a plurality of laminations from the strip, and
• stacking the laminations to form a laminated core and annealing the laminated core at a temperature between 730° C. and Tα/γ.