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Specimen mounting methods for metallography

Description: >The development of metallographic mounting methods is reviewed and several of the more common methods being used are discussed. Characteristic advantages and disadvantages are pointed out. Retention of sample edges for examination is essential in many investigations, and a separate section is devoted to the many techniques devised to achieve this goal. It is noted that there is a mounting technique available for virtually any type of specimen. (14 figures, 6 tables, 57 references) (JRD)
Date: January 1, 1973
Creator: Miley, D. V. & Calabra, A. E.
Partner: UNT Libraries Government Documents Department

Can-rolling of beryllium ingots

Description: Aspects of hot-rolling cast-beryllium billets canned in 304 stainless steel are examined. Emphasis is placed on the development of the proper rolling schedule to completely convert the columnar cast structure to a uniform equiaxed one. Also emphasized are curling difficulties found in rolling this two-metal composite. The curling is found to depend chiefly on friction between ths billet and work rolls. Lubrication and roll surface finish are found to be the key variables which in turn control friction. Curling is best prevented by having a higher friction coefficient on the bottom billet surface than on the top during rolling. (auth)
Date: October 15, 1973
Creator: Floyd, D. R.; Leslie, W. W. & Dolechek, L. F.
Partner: UNT Libraries Government Documents Department

Causes of the yield-point phenomenon in commercial beryllium products

Description: The variables of iron content, texture, and grain size are studied as a function of solutionizing, aging, and strain-aging heat treatments. Results show that the yield point is caused by precipitate pinning. Furthermore, precipitation is enhanced by pre-strain, which can be introduced by elevated- temperature working, rapid cooling, or tensile elongation at room temperature. Aging is effective between 400 and 760 deg C, depending on the type of pre- strain, iron content, and texture. Cottrell-type solute pinning is not observed, and the Rahn model for yield drops in bcc metals best explains these results. Texture increases the likelihood of a yield point occurring. In the case of extruded-flat stock, texture causes a 3-fold increase in the amount of hardening accompanying the yield point when compared to hot-pressed block. Yield points appear on aging and strain-aging for orientations favoring either prism or basal flow. Fine grain size is a necessary condition for the occurrence of a yield point. A yield point can occur if: the average grain size is less than 10 microns, the microstructure is duplex and has a large number of grains less than 5 microns in size, a substructure exists with subgrains less than 5 microns in size. Grain-growth anneals can irreversibly eliminate a yield point. Differences in the frequency of appearance of yield points can be explained by the above factors, and a strong yield point can be developed in material supplied by Brush and KBI by appropriate treatment. The solid-solution hardening effect of iron on yield stress is linear with a slope of 2.3 psi per ppM in the range of iron from 840 to 5850 ppM. The grain-size effect, in the range from 8 microns to 45 microns, is seen to be linear for a Hall--Petch plot of yield stress versus inverse square root of ...
Date: February 1, 1974
Creator: Floyd, D. R.
Partner: UNT Libraries Government Documents Department