An alien substance removing apparatus according to one embodiment of the present invention may comprise: a hood unit provided adjacent to an electrical steel sheet and for collecting an alien substance generated in the electrical steel sheet by laser irradiation; and a scraping unit coupled to the hood unit and scraping and removing the alien substance attached to one surface of the hood unit facing the electrical steel sheet.

An alien substance removing apparatus according to one embodiment of the present invention may comprise: a hood unit provided adjacent to an electrical steel sheet and for collecting an alien substance generated in the electrical steel sheet by laser irradiation; and a scraping unit coupled to the hood unit and scraping and removing the alien substance attached to one surface of the hood unit facing the electrical steel sheet.

A grain-oriented electrical steel sheet includes a plurality of linear deformable portions formed on a surface of the electrical steel sheet in a rolling direction, wherein an interval between the deformable portions changes to correspond to a grain size of grains over the entire length of the steel sheet, and at least two regions in which intervals between the deformable portions are different exist.

A grain-oriented electrical steel sheet includes a plurality of linear deformable portions formed on a surface of the electrical steel sheet in a rolling direction, wherein an interval between the deformable portions changes to correspond to a grain size of grains over the entire length of the steel sheet, and at least two regions in which intervals between the deformable portions are different exist.

A manufacturing method of a grain-oriented electrical steel sheet according to an embodiment of the present invention includes producing a cold-rolled plate; forming a groove in the cold-rolled plate; performing primary recrystallization annealing to the cold-rolled plate; and applying an annealing separator to the primary-recrystallized cold-rolled plate and performing secondary recrystallization annealing, wherein a weight ratio of SiO.sub.2/Fe.sub.xSiO.sub.y of the surface layer part of the cold-rolled plate is 0.3 to 3 after the primary recrystallization annealing of the cold-rolled plate. (Here, x is an integer from 1 to 2, and y is an integer from 2 to 4.)

The present disclosure provides a method for protection against fretting fatigue by compound modification via laser shock peening and coating lubrication, where a group of micro-pits distributed into a regular array is firstly formed in a surface of a metal material by using laser shock peening, with a single micro-pit having a diameter of 1 to 10 mm and a depth of 1 to 20 μm; and the micro-pits are then coated with a lubricant by coating preparation. Based on the micro-pit styling feature and surface residual compressive stress introducing feature of the laser shock peening, with compound modification by surface texturing via the laser shock peening and coating lubrication, the surface of the material can be reinforced by residual compressive stress, coating lubrication and surface micro-pit texturing with a synergistic effect, thus allowing for improved fretting fatigue behavior of the material.

A component of a crawler type machine is hardened by explosive depth hardening. The component is typically a crawler track shoe (10), and the roller path surface (11) of the track shoe and immediate underlying metal portion are pre-hardened by placing explosive charge (15) on the surface of the track shoe (10), and detonating the explosive charge to impart a high force on the surface and underlying metal portion for a short duration. The resultant shock wave causes high-velocity deformation at a high stress level, which leads to intensive development of plastic displacement at microscopic size. This increases the hardness and the strength of the surface and underlying metal portion. The surface (11) may be hardened by repetitive explosive depth hardening. Grooves (20) may also be formed in the roller path (11) to accommodate any flow of material. Explosive depth hardening can be applied to other surfaces of the track shoe (10), such as the pin bore of a connection lug, or to other components such as a drive tumbler of the crawler.

A component of a crawler type machine is hardened by explosive depth hardening. The component is typically a crawler track shoe (10), and the roller path surface (11) of the track shoe and immediate underlying metal portion are pre-hardened by placing explosive charge (15) on the surface of the track shoe (10), and detonating the explosive charge to impart a high force on the surface and underlying metal portion for a short duration. The resultant shock wave causes high-velocity deformation at a high stress level, which leads to intensive development of plastic displacement at microscopic size. This increases the hardness and the strength of the surface and underlying metal portion. The surface (11) may be hardened by repetitive explosive depth hardening. Grooves (20) may also be formed in the roller path (11) to accommodate any flow of material. Explosive depth hardening can be applied to other surfaces of the track shoe (10), such as the pin bore of a connection lug, or to other components such as a drive tumbler of the crawler.

A remanufacturing method for a metal part having a damage. The damage groove is divided into a number of levels, and the groove bottom is treated by absorption layer-free laser shock peening to remove surface impurities and to refine surface-layer crystal grains. Then a cladding layer is formed by laser cladding. The process is repeated until the groove is completely filled by the cladding layer to higher than the surface of the metal part and the cladding layer higher than the surface is cut by a mechanical processing and polished, and the upper surface of the laser cladding layer is subjected to large-area overlapped laser shock peening.

A remanufacturing method for a metal part having a damage. The damage groove is divided into a number of levels, and the groove bottom is treated by absorption layer-free laser shock peening to remove surface impurities and to refine surface-layer crystal grains. Then a cladding layer is formed by laser cladding. The process is repeated until the groove is completely filled by the cladding layer to higher than the surface of the metal part and the cladding layer higher than the surface is cut by a mechanical processing and polished, and the upper surface of the laser cladding layer is subjected to large-area overlapped laser shock peening.