With a hot-rolled steel sheet for electrical steel sheet production having a scale layer on the surface, where the surface of the steel sheet has a lightness L* as defined in JIS Z 8781-4: 2013 satisfying 30≤L*≤50, and chromaticities a* and b* as defined in JIS Z 8781-4: 2013 satisfying −1≤a*≤2 and −5≤b*≤3 respectively, and with one end portion in the longitudinal direction of a coil as a reference, a color difference ΔE.sub.ab* as defined in JIS Z 8781-4: 2013 at the central portion and at the opposite end portion satisfies ΔE.sub.ab*≤8, it is possible to obtain a grain-oriented electrical steel sheet where the variation of properties in a product coil is small.

With a hot-rolled steel sheet for electrical steel sheet production having a scale layer on the surface, where the surface of the steel sheet has a lightness L* as defined in JIS Z 8781-4: 2013 satisfying 30≤L*≤50, and chromaticities a* and b* as defined in JIS Z 8781-4: 2013 satisfying −1≤a*≤2 and −5≤b*≤3 respectively, and with one end portion in the longitudinal direction of a coil as a reference, a color difference ΔE.sub.ab* as defined in JIS Z 8781-4: 2013 at the central portion and at the opposite end portion satisfies ΔE.sub.ab*≤8, it is possible to obtain a grain-oriented electrical steel sheet where the variation of properties in a product coil is small.

The invention provides an endless rolling method based on temperature uniformity control, and belongs to the field of iron and steel metallurgy. By optimizing the process path, a new layout mode is adopted, a double heat storage soaking furnace and a descaling box are additionally arranged, transverse and longitudinal bonding magnetic induction heating device is adopted, transverse and longitudinal temperature uniform of the slab in the rolling process is realized, the cross section temperature difference is reduced, and the product quality is improved. On the basis of five-stand arrangement of a traditional finish rolling mill, a rolling mill is additionally arranged to serve as a standby rolling mill, such that on-line non-shutdown change roller of the finish rolling mill is realized. The method of the invention realizes a full-continuous production of production and meets the high-quality development requirements of iron and steel metallurgy, such that traditional cool rolling can be replaced with hot rolling, traditional thick-specification strip can be replaced with high-added-value thin specification strip. There is important significance in the aspects of productivity optimization layout, green manufacturing, intelligent manufacturing and the like.

A method for descaling a sheet of metal include first and second descaling components that each have a single motor driven slurry propelling impeller mounted on a top and bottom of an enclosure. The top and bottom mounted impellers of the first component are configured to propel slurry onto a sheet of metal passing through the enclosure across the entire width of the sheet of metal in a first direction extending from one lateral side to an opposite lateral side of the enclosure. The top and bottom mounted impellers of the second component are configured to propel slurry onto a sheet of metal passing through the enclosure across the entire width of the sheet of metal in a second direction opposite the first direction and extending from the opposite lateral side to the one lateral side of the enclosure.

A method for descaling a sheet of metal include first and second descaling components that each have a single motor driven slurry propelling impeller mounted on a top and bottom of an enclosure. The top and bottom mounted impellers of the first component are configured to propel slurry onto a sheet of metal passing through the enclosure across the entire width of the sheet of metal in a first direction extending from one lateral side to an opposite lateral side of the enclosure. The top and bottom mounted impellers of the second component are configured to propel slurry onto a sheet of metal passing through the enclosure across the entire width of the sheet of metal in a second direction opposite the first direction and extending from the opposite lateral side to the one lateral side of the enclosure.

An efficient straight through medium-heavy plate production line of double rack and double shearing line and a production method are provided. The medium-heavy plate production line comprises: a main rolling line, at least two parallel shearing lines, and straightening stacking lines that are each configured parallel outside each of the shearing lines, the main rolling line comprises: a heating furnace, a high pressure water descaling machine, a fixed width press, a stand roller, a four-roll roughing mill, an intermediate cooling device, a four-roll finishing mill, an ACC accelerated cooling device, a hot straightening machine, a 1# labeling device and a hot segmenting shear are arranged in order, and a 1# cooling bed, a 1# inspection stand, a 2# cooling bed and a 2# inspection stand are arranged at two sides of the steel rolling and delivery rolling way; a plate turnover machine; and a traverse stand.

The present invention relates to a method of steel sheet surface treatment, wherein, the method comprises sequentially: a strip surface treatment unit (1) configured with a high pressure spraying device (1-1) or a centrifugal ejecting device (1-2), a strip surface rinsing unit (2), and a strip surface dry unit (3). Either or both of the high pressure spraying devices (1-1) and the centrifugal ejecting devices (1-2) are arranged, and spray onto the strip surfaces with a mixture of solid abrasives and water, i.e., slurry. Additionally, the method of steel sheet surface treatment comprises: a slurry supplying unit (4) and an abrasive recycling unit (5). When the method of the present invention is applied into the strip post processing line, it can control the surface roughness of the steel sheet, while clearing away grease, scales and some contaminations thereon, through impacting the mixture of water and solid particles with a certain ratio onto the surfaces of the strip steel. When the method of the present invention is applied into the finishing processing line, it can control the surface roughness of the steel sheet, while adjusting the mechanical properties of the strip, thereby completely or partially replacing the skin pass process.

The present invention relates to a method of steel sheet surface treatment, wherein, the method comprises sequentially: a strip surface treatment unit (1) configured with a high pressure spraying device (1-1) or a centrifugal ejecting device (1-2), a strip surface rinsing unit (2), and a strip surface dry unit (3). Either or both of the high pressure spraying devices (1-1) and the centrifugal ejecting devices (1-2) are arranged, and spray onto the strip surfaces with a mixture of solid abrasives and water, i.e., slurry. Additionally, the method of steel sheet surface treatment comprises: a slurry supplying unit (4) and an abrasive recycling unit (5). When the method of the present invention is applied into the strip post processing line, it can control the surface roughness of the steel sheet, while clearing away grease, scales and some contaminations thereon, through impacting the mixture of water and solid particles with a certain ratio onto the surfaces of the strip steel. When the method of the present invention is applied into the finishing processing line, it can control the surface roughness of the steel sheet, while adjusting the mechanical properties of the strip, thereby completely or partially replacing the skin pass process.

Provided is a hot-rolled steel sheet having a composition containing 0.04 mass percent to 0.20 mass percent C, 0.7 mass percent to 2.3 mass percent Si, 0.8 mass percent to 2.8 mass percent Mn, 0.1 mass percent or less P, 0.01 mass percent or less S, 0.1 mass percent or less Al, and 0.008 mass percent or less N, the remainder being Fe and inevitable impurities. Internal oxides containing one or more selected from the group consisting of Si, Mn, and Fe are present at grain boundaries and in grains in a base metal. The internal oxides present at the grain boundaries in the base metal are located within 5 μm from the surface of the base metal. The difference between the depths at which the internal oxides are formed in the cross direction of the steel sheet is 2 μm or less.

Provided is a hot-rolled steel sheet having a composition containing 0.04 mass percent to 0.20 mass percent C, 0.7 mass percent to 2.3 mass percent Si, 0.8 mass percent to 2.8 mass percent Mn, 0.1 mass percent or less P, 0.01 mass percent or less S, 0.1 mass percent or less Al, and 0.008 mass percent or less N, the remainder being Fe and inevitable impurities. Internal oxides containing one or more selected from the group consisting of Si, Mn, and Fe are present at grain boundaries and in grains in a base metal. The internal oxides present at the grain boundaries in the base metal are located within 5 μm from the surface of the base metal. The difference between the depths at which the internal oxides are formed in the cross direction of the steel sheet is 2 μm or less.