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none of these conditions may definitely be assigned as the cause of failure, but
 

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Photograph No. 7. (x75. ) (130)

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Photograph No. 8. (x75. ) (131)

Photomicrographs Nos. 7 and 8 show the characteristic appearance of this slag on the unetched surface. The crystalline structure which became evident upon etching was rather coarse, and indicative of imperfect heat treatment, though very great grain refinement is not to be expected in masses of metals of this size… (p236)

Illustrating “Examination of Additional Fragments from the Jacket of 12-inch Gun No. 58,” reprinted in Report of the Tests of Metals and other Materials Made at the United States Testing Laboratory at Watertown Arsenal, Massachusetts, during the Fiscal Year Ended June 30, 1915 (1917): 235-237.
sources: epigram; pictura.
 

7 December 2012
tags: emblemata ferrum; failure; ingotism; rounds