A sensitive diamond indenting tool was developed which gives indentations of accurately measurable length in the most resistant steels with loads of less than 1 kg. It was found that the use of these light loads permits extension of indentation tests to small specimens and to tests of brittle materials, such as glasses, which shatter under the heavy loads required by present indenters.The indenter is pyramidal in form, giving a diamonn-shaped (rhomb) indentation of which the diagonals have an approximate ratio of 7 to 1 instead of 1 to 1 for the square-based pyramid. Such indenters were duplicated to the required accuracy and showed no discernible wear with use.Elastic recovery of indentations with this indenter takes place in a transverse rather than a longitudinal direction, and, consequently, from the measured length of the long diagonal and the constants of the indenter, unrecovered dimensions of an indentation are obtained. Results of tests are expressed as indentation numbers which relate the applied load in kilograms to the unrecovered projected area in square millimeters.Recovered projected areas also, may be determined with an added measurement of the short diagonal. Since knowledge of both recovered and unrecovered dimensions may be obtained, the indenter offers possibilities for study of the fundamentals involved in indentation testing that are not afforded by ball, cone, and square-based pyramidal indenters, which, because of their symmetrical form, yield recovered dimensions only.The performance of seven indenters of different angular formation was investigated to determine their relative sensitivity and adaptability for use in different materials and to determine also the effect of load and of different dimensional bases of computation on indentation number. Consideration of the results led to the selection of an indenter which gives excellent performance in many materials. Comparison is made of indentation numbers given by this indenter and corresponding Brinell and Vickers numbers for the same specimens. CONTENTS Faga

An investigation on impact resistance of FDM processed Nylon-12 parts using response surface methodology

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