Abstract: A method for using a lifting magnet and a lifting magnet. The lifting magnet includes a plurality of electromagnet coils that are each independently ON/OFF-controllable and voltage-controllable, and a magnetic pole that is excited by application of a voltage to the electromagnet coils. An electromagnet coil to be used for lifting steel plates is determined based on a total thickness of the steel plates to be lifted. An amount of passing magnetic flux ?r in the magnetic pole in a case where magnetic flux passes through only the steel plates to be lifted when the electromagnet coil is used is calculated. An application voltage to be applied to the electromagnet coil used for lifting the steel plates is determined based on the amount of passing magnetic flux ?r. The application voltage is applied to the electromagnet coil.

Abstract: Provided is an abrasion-resistant steel plate which has high hardness up to the mid-thickness part thereof although the steel plate is 50 mm or more, and can be manufactured at low cost. The abrasion-resistant steel plate has a specific chemical composition having DI* of 120 or more, where DI* is defined by the following Formula (1): DI*=33.85×(0.1×C)0.5×(0.7×Si+1)×(3.33×Mn+1)×(0.35×Cu+1)×(0.36×Ni+1)×(2.16×Cr+1)×(3×Mo+1)×(1.75×V+1)×(1.5×W+1) . . . (1), has HB1 of 360 HBW10/3000 to 490 HBW10/3000, HB1 being a Brinell hardness at a depth of 1 mm from a surface, has a hardness ratio, HB1/2 to HB1, of 75% or more, HB1/2 being a Brinell hardness at a mid-thickness position, and has a plate thickness of 50 mm or more.

Abstract: Provided is an abrasion-resistant steel plate which has high hardness up to the mid-thickness part thereof although the steel plate is 50 mm or more, and can be manufactured at low cost. The abrasion-resistant steel plate has a specific chemical composition having DI* of 120 or more, where DI* is defined by the following Formula (1): DI*=33.85×(0.1×C)0.5×(0.7×Si+1)×(3.33×Mn+1)×(0.35×Cu+1)×(0.36×Ni+1)×(2.16×Cr+1)×(3×Mo+1)×(1.75×V+1)×(1.5×W+1) . . . (1), has HB1 of 360 HBW10/3000 to 490 HBW10/3000, HB1 being a Brinell hardness at a depth of 1 mm from a surface, has a hardness ratio, HB1/2 to HB1, of 75% or more, HB1/2 being a Brinell hardness at a mid-thickness position, and has a plate thickness of 50 mm or more.