Abstract: A cutting device for collecting a quantoback analysis sample in a hot state from a preferred position of a continuously cast steel piece is disclosed. According to this invention, a dish like recess is cut on the surface of a cast steel piece while leaving a center column, then the root of the center column is cut and the cut free portion taken out as a sample.

Abstract: A method and a device for collecting a quantoback analysis sample in hot state from a preferred position of a continuously cast steel piece are disclosed. According to this invention, a dish like recess is cut on the surface of cast steel piece while leaving a center column, then the root of left center column is root cut and taken out as sample. A cutting device and a way for accessing the cutting device are presented for operating this process.

Abstract: A combustible stencil held by holders is disposed at a position some distance apart from the end face of a hot material; immediately thereafter, a coating composition is sprayed onto the hot material through perforations of the stencil from behind to carry out the marking; the stencil is used only once and burned by the potential heat of the hot material upon marking; and a new stencil is used each time for marking. The combustion starting time is controlled by previously moistening the stencil as necessary.

Abstract: A blast-furnace tuyere having excellent thermal shock resistance and high durability consists of a tuyere substrate composed of copper or copper alloy, a self-fluxing alloy metallized layer sprayed on the substrate, a cermet coating sprayed on the alloy metallized layer, and a ceramic coating sprayed on the cermet coating. The cermet coating is made from a mixture of an alloy material consisting essentially of 5 to 60 wt% of Co, 5 to 50 wt% of Ni, 5 to 25 wt% of Cr, 5 to 40 wt% of Mo, 5 to 40 wt% of W, 3 to 40 wt% of Si and inevitable impurities, and a ceramic eutectic material consisting essentially of 95 to 65 wt% of Al.sub.2 O.sub.3, 5 to 30 wt% of ZrO.sub.2, 2 to 20 wt% of TiO.sub.2, 3 to 30 wt% of SiO.sub.2 and inevitable impurities. The ceramic coating is made from the same ceramic material as used in the formation of the cermet coating.