Abstract: Decarburized grain oriented silicon steel is provided with an annealing separator which forms a glass film after the final high temperature anneal. The magnesia used as the annealing separator has a total chlorine level of 0.01 to 0.20% by weight based on the weight of magnesia with at least 0.01% metal chloride selected from the group of Mg, Ca, Na and K. The chloride addition acts to seal the coating surface during the final anneal to control diffusion and stabilize the secondary grain growth. The glass film which forms during the anneal may be laser scribed for domain refinement without coating damage. The magnesia may also contain additions of phosphates, TiO.sub.2, SiO.sub.2, Cr and B. The temperature of the magnesia is maintained below 25.degree. C. to control hydration and eliminate the need for other additives in the magnesia slurry to control hydration.

Abstract: The present invention relates to a process for producing permanent domain refinement continuously and at very high line speeds in grain oriented electrical steel having an aluminum nitride inhibitor system. After the final high temperature anneal, the glass film and insulative coating on the surface is removed in narrow bands (grooves or rows of spots). The steel is electroetched to increase the depth of the bands, coated with aluminum by electrophoresis and given a stress relief anneal to bond the aluminum coating to the base metal by diffusion. A localized stress field is induced during cooling which causes domain refinement due to the differential thermal contraction between the aluminum and the base metal.

Abstract: Oriented silicon steel is heated in a slab furnace at temperatures above 1260.degree. C. prior to hot rolling. The slab surfaces in the furnace are exposed to molten slag, variable atmosphere conditions and refractory interaction from the hearth. The slab surface prior to hot rolling has a major importance for cold rolling and the quality of the glass film.A rapid oxidation treatement of the slab just prior to the scale breaker or first rolling stand corrects a silicon-free iron layer condition which causes streaks in the glass film. The oxidation treatment blows gas having at least 30% oxygen for a sufficient time and velocity to provide a surface which will develop a continuous fayalite layer in subsequent processing and provide for the formation of a continuous glass film.

Abstract: A system for measuring the relative elongation of portions of a moving steel strip. A number of capacitive sensors positioned above one surface of the moving strip monitor the distance between each sensor and the surface of the strip. This information is processed through a geometrical relationship to calculate the percent relative elongation at one sensing position with respect to another. The calculation may be performed instantaneously, or result from several measurements averaged over a cell length. Provision is made for greater accuracy in cases where waviness of the strip results in the occurrence of more than a predetermined number of waves during a cell length. Wave steepness, wave periodicity, and categorization of relative length information are also provided by the processing.

Abstract: A high temperature box annealing furnace for metallic coil annealing practices. The furnace comprises a fixed base and a removable bell capable of achieving a sealed relationship with the base. The interior of the bell side walls, end walls and roof are lined with ceramic fiber insulation and are provided with electrical resistance heating elements. The heating elements are divided into at least two separately controllable zones, a first zone including the heating elements mounted on the bell roof and the upper portions of the bell side and end walls and a second zone including the heating elements mounted on the lower portion of the bell side and end walls. The base comprises a steel framework supporting a cast refractory base member configured to support one or more coils. Each coil is provided with a cover and the cast refractory base member provides a sand seal for the lower edge of the covers. The cast refractory base has an atmosphere inlet for each coil positioned at the center or eye of the coil.

Abstract: Method and apparatus for monitoring the flatness characteristic of a moving electrically conducting strip of material by continuously measuring the change in capacitance between the strip surface and a fixed point adjacent the surface. The capacitance is measured by means of a sensor having an active plate surrounded by a guard plate for eliminating stray capacitance, both plates being impressed with a high frequency signal. Changes in capacitance associated with both plates are eliminated while changes in capacitance associated with only the active plate are covered to a voltage proportional to the inverse of the spacing between the active plate and the strip surface. A plurality of the sensors may be spaced across the width of the plate for providing a profile of the strip flatness characteristics. The sensor finds particular application for monitoring and characterizing bottom buckles in steel strip following high temperature annealing.

Abstract: An audio and/or visual signal device is mounted on a pinball machine for signaling to the area surrounding the machine that a replay game or the like has been awarded. The signal device is connected through a relay to a source of electric power. The relay is energized by a magnetic reed switch adapted to be mounted in close association with a solenoid operated knocker within the machine so that the switch is magnetically closed when the knocker is operated.