Abstract: The internal quality of continuously cast and other steel samples in the form of ingots, billets, blooms, slabs and bars is determined in rapid manner to enable potentially problem-causing casting conditions to be identified and corrected in timely manner. A steel sample from the casting, after grinding to remove any heat-affected zone and to provide a desired degree of surface roughness, is anodically etched using dilute hydrochloric acid at ambient temperature to etch away metal from the surface to reveal the internal quality. After removal of the sample from the etching apparatus, the sample is washed, dried, and visually examined to determine the internal quality.

Abstract: A stencil case and a plurality of cards are provided for use with the stencil case. The stencil case has a front panel and can receive a card such that the card lies adjacently behind the panel. The panel has a first surface region containing a window through which a user can view the adjacently lying part of a card, a second surface region containing a stencil, and a third surface region bearing indicia associated with what is seen through the window when any one of the plurality of cards is received adjacently behind the panel. Each card has a front face and a reverse face, the front face having a first region containing a picture or indicia that will be visible through the window when the card lies adjacently behind the front panel. Each card further contains a second region for receiving a stencilled marking through the stencil of the front panel. The combination is intended to be used as an educational aid.