Abstract
Recently a new testing method for an opaque body called "Sump" was invented by Mr. J. Suzuki, the spelling of which came from the capitals of Suzuki's Universal Micro Printing. In this method we require no test pieces cut from body as in ordinary microscopic examination, but only use celluloi, giving some plasticity with a solvent like amil acetate, and directly stick it tightly on any surface. Soon after we tear it off from the body and bring it under a common simple microscope getting a precise micro-structure very clearly.
The writers tried to apply this method to iron and steel and designed a small portable box which contained in good order various et hing and cleaning reagents etc., and went out to many works with this box and with a small grinder to take various Sump printings.
In the first time we studied the technical skill of gaining clear micro-structures for steels of carbon 0.06 0.24 0.43 0.60 % to find that the polishing degree of test surface is almost the same with common microscope samples but requires some deeper etching to get clear structures of their ferrite and pearlite etc, and even for quenched steel we could see clearly in Sump printing those fine structures of martensite and troostite etc. in 500 magnification, and on the other hand various flaws of steel were also revealed distinctly by this printing. Next, for grey and white cast irons we could find their structure and small blow holes more easily, and especially in the former the difference of graphites and holes which has been very difficult to distinguish in ordinary metal microscope, appeared very clearly as graphites were white, holes were black, and is very interesting for cast iron investigators. Furthermore we succeeded to apply this method on the testing of defects, structures, or homogeneity of heavy materials e.g. chilled iron rolls etc.
Thus in this method we could prove the possibility of examining and studying the structure, cracks etc. very simply for iron and steel without any distinction of their size and form, with no fear of spoiling them.
Therefore the application of this new method will be very wide in all sides in future not only in iron and steel but also probably in all kinds of other metals.
