Document Z1w3KJybLv5a2RodpY1kdovp

192 Trceuty-fifth Xaiifinal Safety Congress Members at Aur(V>~ Cvbjl Aixswiftm. American Stanhnli Aittinin. New York. X. V. C. H. A\*n_ Wv.MntchMUM.* Elearic and Manufacturing Ci. I*a.< Pittstrargti. Pa. 1. |l.\XA>iii. Gwollinc 1engineer. Chtcagis 111. r, \\. Itfa'K. Cnnul 5wtw Kuhhcr Prixlttei*. Inc- New York. X. Y. II. K. ISisus. L'ni Carliwlc and CarUm Cn- N*w York. X. V. (MrtrutxJitan Chapirr) j*7 j)t`u.AM. E. L). Pellard Gr San Franciscu. Calif. (San Franci*c* Chapter) H- GiLwr. Amencan Cpnawid Cv IJndvn. X. I. (Xw Jctkv Chapter) Gonwix. Philadelphia Electric Co- Philadelphia, Pa. (Philadelphia Chapter) VY. M. Graff. National Bureau nf Camlijr & Surety Underwriters. New York. X. Y. H. J. GviFFiTfi. Jwm & t^nghlin Steel Cnrp. Pittdiorgh. Pa. (Western Pennsylvania Safelv Council Chapter) R. McA. Kkuvs. Industrial Commission of Wisconsin. Madison. Wis. J. M. Kkbbican. United States Ruhlicr Redaiming Gl. Inc. Buffalo, X. Y. (Niagara Frontier Chaj*tcr) Emerr F. Kixr. Jjcvct Rrmhers Co- Cambridge. Mass. (Poston Chapter) Tumi as K. I.tcitmnr. Tlte Kuppvr* Cnstl Co- Pittsburgh. Pa. M. Ci. I.tnvt*. National Bureau of Sisnthnh. Washington. I). C. II. I- Minks. K. I. <ln !\u !c Xenumrs & Gil. Wilmington, Del. W. 5. Paint. Aetna Casually fe Inntfancr Gv. Hanford. C<in. Gw. F. PsrssiNc. Unnt Otl Gmtpany of Califiwnia. In Angeles. Calif. IT. F- Ralston. ISttshuruh Plate Glass Co_ Pittsburgh, Pa. A S. RtctXA, Industrial Relations Cuunselnrs. Inc. New York. X. Y. G. K. Saxkubl General Electric Cn- Schencctadr. X. Y. C. \Y. Smith. Standard Oil Cv (Inti.). Chicago! IU. H. S. Siirnt. Union Carbide and Carbon Gup- Xew York. X. Y. R. C. Stratton. The Travelers Insurance Gl. Ilanfnrd, Conn. R. F. TiiALXKa. Rtdek Motor Company. Flint. Midi S. E. WitrnNr- Liberty Mutual insurance Gl. Boston. Mass. William P. Yant. Mine Safety Appliances Gl. Pittsburgh. Pa. WEDNESDAY NOON SESSION October. 7. 1936 The annual meeting of tin- ASSEEngineerhtg Section oi the National Safety Council followed a luncheon ami convene*! with C. W. Smith. Standard tlil Co. (Ind.l. Chicago, general chair* ntatu presiding. All ropuns had been miimrographrd. and M|nc* were I<strib* oted at the luncheon. ))r. Francis .F. Lucas. Menther. Tech* nieal StafT, Bell Telephone Ulturatork^, New York City, and international au thority on microscopy and photomicrogra phy. spoke on "Laic l>evek'pments in High Power am) l.lira Violet Micro scopy.** The rcjort of the nominating commit tee was presented by A. S. Kcgnla. chair man. Other mentliers of the committee were S. 1L Whiling. R. F. Tlialner, C B. Attek and Dr. M. G. Lloyd. The commitlce't list of officers, as elected, trill l>c found elsewhere in this sectional record. Other sessions S|*on.ored by the ASSEEngineering Section included those on "Safety Belts,** "Safely Training.** "Ex haust Systems.** "Safety Exchange Round Table.** and "Occupational Diseases.** Reports of these sessions will be fount! elsewhere m the Transactions. American Society of Safety Engineers--Engineering Section 193 Late Developments in High Power and Ultra Violet Microscopy --Their Value from an Accident Prevention Viewpoint for Detecting Flaws in Metal Structures By DR. FRANCI8 P. LUCAS Member Technical Staff and Head of Microscopic Laboratories, Bell Telephone Laboratories. Inc. New York City Dr. Lucas used about 30 lantern slides and discussed each briefly. The high power and ultra-violet microscopes were first illustrated and described. Following this was a group of four slides showing the development of high power metallography. The first photograph showed a specimen of chrome iron (stainless^ iron) at 200 diameters magnification. The structure was so fine that at this magnification little could be seen. The next photograph, at 1000-X, began to show some structure. Ordinarily this would be regarded as a high power micrograph. Next the structure was shown at 4000-X with the best apochromatlc system the world affords- The structure was then resolved to better advantage, but not fully. The `final micrograph was of the same specimen but photographed with the new mono-brom-iuphthalene immersion system of N. A. 1.60 and showed the structure completely resolved- _ Details of structure -- minute carbides of iron and chromium -- measuring about 150 atom di ameters in size were very distinctly resolved. Dr. Lucas showed how this high resolving power system could_ be applied to a stody of fatigue cracks, which vary in width from about 150 atom diameters upward. Cracks to metal bring to mind fatigue phenomena as the cause. If one arrived at this possible conclusion, he would not be far wrong. I shall not be concerned particularly with methods of test, test data and the outward characteristic ap pearance of fatigue fractures. To review very briefly some of the Meat now com monly held on the subject by metallur gists and engineers may refresh the memory. It may be an aid to a better understanding of the new subject of in ternal stress raisers and their influence on the propagation and trend of fatigue cracks. ft is asserted by competent authorities that a very high percentage of metal fail ures occurring in service are of the type denoted as fatigue failures. All fast moving mechanisms whose loads are cither intermittent or reversed cycles of stress may develop fatigue type failures. Literally thousands of things in every day use, from a giant ocean liner to the hair spring of a delicate watch, may be subject to fatigue type failures. The advent of the railroad seems to have been responsible for stimulating thought on the subject of the fatigue of metals under repeated stress. A German engineer prevailed upon Prussian State Railways to undertake such an investi gation, and his results have become a classic. His repeated stress tests were reported in the London publication "En gineering" for 1871. The fracture resulting from repeated stress is a brittle, jagged-appearing one. so that at first engineers and investiga tors concluded that the fibre of the metal underwent some change. Oftentimes the fractured surface appears bright and shin ing as though* composed of large crys tals. Observers of these fractures in ferred that a change had occurred in the metal and from the appearance to the eye the theory seems to hare developed that the metal had crystallized and hence had failed. No one seems to have ad vanced any good reason why a crystal lized metal should be weaker and more susceptible to cracking than a non-crys talline one, assuming such existed. But at any rate the crystallization theory per sisted. and it took almost two decades and much microscopy to dispel the delu sion. Even today echoes of this old crys tallization theory may be heard from en gineers. As a matter of fact, metals are inher ently crystalline. The crystals at times may be large and eqoi-axed or they may