METHODS OK CASTING TEST BARS FOR THE A. F. A. 551
measured. The few records shown will give a fair idea of the ratio of contraction in the large and small bars.
To obtain the chill, the author devised the form of test block seen in Figs. 135 and 145, pages 548 and 559. It was made of the wedge form seen, so that the block could be used throughout all the different grades. These chilled tests were cast in a core having one face part chill and part core, as seen at E' and H', Fig. 135. The chill E' was ijX inches thick. The chill tests, Figs. 145 to 147, pages 559 and 563, chilled but slightly at the top points and face, while the chill for chilled rolls (not shown) are all chilled, showing the hard nature of iron used for chilled rolls, etc.
The fluidity of the metal was tested by means of two fluidity strips VH inch, thick at their base, running up to a knife-edge 14 inches long, as seen at X, Figs. 131 and 135, pages 541 and 548. The principle involved in these fluidity strip tests is the same as described for those shown on pages 515 to 517, and. they serve to show the difference that might exist between the fluidity of the various sets of test bars that were made and noticed in connection with the tests recorded from pages 558 to 570.
The different kinds of physical tests consisted of transverse, deflection, tensile, compression, contraction, and chill tests. The bars varied, in size from y% inch, square and round, increasing }4 inch in size in each class up to 4 inches square and 4)4 inches round for transverse tests, and from )4 inch square and round to about 2 inches square and 2)^ inches round for tensile tests. There were four bars of each kind and size made in green sand and four bars of eacho risers were carried from the two outside