Fe-Ni based permalloy and method of producing the same and cast slab

A Fe—Ni based permalloy made of a hot rolled sheet comprising Ni:

• 70-85 wt %, C:
• not more than 0.015 wt %, Si:
• not more than 1.0 wt %, Mn:
• not more than 1.0 wt %, P:
• not more than 0.01 wt %, S:
• not more than 0.005 wt %, 0:
• not more than 0.006 wt %, Al:
• not more than 0.02 wt %, and not more than 15 wt % of at least one selected from the group consisting of Mo, Cu, Co and Nb within a range of not more than 20 wt % in total, and having such magnetic properties that a maximum magnetic permeability μm is not less than 400000, an initial magnetic permeability μi is not less than 200000 and a coercive force Hc is not more than 0.006 (Oe), provided that Ni segregation amount CNis represented by the following equation is not more than 0.15 wt %:
• CNis=analytical value of Ni component (wt %)×CiNis (c.p.s.)/CiNiave. (c.p.s.)
• wherein CiNis:
• a standard deviation of X-ray intensity (c.p.s.)
• CiNiave.:
• an average intensity of total X-ray intensities (c.p.s.).

A method of producing a Fe—Ni based permalloy, which comprises casting an alloy comprising Ni:

• 30-85 wt %, C:
• not more than 0.015 wt %, Si:
• not more than 1.0 wt %, Mn:
• not more than 1.0 wt %, P:
• not more than 0.01 wt %, S:
• not more than 0.005 wt %, O:
• not more than 0.0060 wt %, Al:
• not more than 0.02 wt % and the remainder being Fe and inevitable impurities into a slab, and subjecting the cast slab to a homogenizing heat treatment and further to a hot rolling.

A method of producing a Fe—Ni based permalloy, which comprises casting an alloy comprising Ni:

• 30-85 wt %, C:
• not more than 0.015 wt %, Si:
• not more than 1.0 wt %, Mn:
• not more than 1.0 wt %, P:
• not more than 0.01 wt %, S:
• not more than 0.005 wt %, O:
• not more than 0.0060 wt %, Al:
• not more than 0.02 wt % and not more than 15 wt % of at least one selected from the group consisting of Mo, Cu, Co and Nb within a range of not more than 20 wt % in total and the remainder being Fe and inevitable impurities into a slab, and subjecting the cast slab to a homogenizing heat treatment and further to a hot rolling.

A cast slab for a Fe—Ni based permalloy comprising Ni:

• 30-85 wt %, C:
• not more than 0.015 wt %, Si:
• not more than 1.0 wt %, Mn:
• not more than 1.0 wt %, P:
• not more than 0.01 wt %, S:
• not more than 0.005 wt %, O:
• not more than 0.0060 wt %, Al:
• not more than 0.02 wt % and the remainder being Fe and inevitable impurities, and having such a cast texture that an area ratio of equiaxed crystal is not more than 1%.