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By W. W. Gerberich

SINCE the original formulation of fracture mechanics concepts,&apos;y2 relatively little work has related the fracture mechanics description of metal behavior on a gross, structural component scale to the behavior of its microstructural constituents. The purpose of this note is to suggest the utilization of fracture mechanics to describe material behavior on a microscopic scale. A Fracture Concept for Two-Phase Structures. A critical displacement concept considering the tough unidirectional phase in a relatively brittle matrix is first examined. It is assumed that a flaw exists at position 1 as depicted in Fig. 1. As the crack moves from position 1 to 2 the plastic zone could be of the shape described with the size approximated by the Dugdale3 model: where c is the half-crack length, OO is the applied stress, and oyS is the yield strength. Hahn and Rosen-field4 have presented a simple fracture criterion for homogeneous materials based upon the displacement at the crack tip. They also have shown the equivalence of the critical displacement, v*, to fracture toughness by Kc = (2v*oysE)1/2 [2] The displacement at the crack tip is given by and the displacement at any distance in front of the crack tip may be determined knowing the plastic zone size and utilizing the development of Goodier and Field.5 Recalling Fig. 1, the value of v* for fracture in material M1 may be calculated from Eq. [2] providing the critical stress intensity factor is known. As the material is loaded, when vc > vM1 the crack moves from position 1 to position 2 where it encounters the tough second phase. If vc2 < vm2, then the crack will be arrested providing the width of the M2 phase is sufficiently large. This condition is necessary since the displacement at position 2 has increased due to the longer crack length. Thus, the displacement at the distance X (representing the dimension of the second phase) in front of the crack may be larger than the critical displacement for failure in the brittle material. If v, > vm, then failure will proceed in the brittle material. The value of v, may be calculated as indicated above. This latter consideration is the same as predicting fracture of a brittle second phase at some distance in front of a crack located in a ductile matrix. Experimental Evidence. On a macrostructural scale, tungsten wires in a ductile Be-Cu matrix are seen to fracture well ahead of the main crack front in Fig. 2. Utilizing a Kc value of 14.2 ksi-in.1/2 obtained by Schroder et al.6 for as-received tungsten, the critical displacement 2v*, for fracture is calculated from Eq. [2] to be about 6.5 X 10-5 in. The crack tip displacement, 2vc, is calculated from Eq. [3] to be 0.0028 in. indicating that fracture would occur at a considerable distance in front of the crack tip. From the ratio of v*/vc and the plastic zone estimate of Eq. [I], the distance in front of the crack tip at which a tungsten wire should fracture is calculated to be about 0.195 in. As shown in Fig. 2, a fractured wire occurs at a distance of 0.140 in. (fractured in three places), not at 0.250

Jan 1, 1968

By Pol Duwez, Paul Pietrokowsky

Titanium and vanadium form a complete series of solid solutions at temperatures above 885°C. Below 885°C, vanadium is slightly soluble in a titanium (about 1.5 pct V at 650°C) and a two-phase a plus ß region extends to 18.5 pct V at 650°C. The alloys up to 15.0 pct V transform into a supersaturated a solid solution upon rapid cooling from the ß phase. Above 15 pct V the ß phase may be retained. The temperature at which the ß to a&apos; martensite-type transformation takes place decreases steadily from 850°C for 0.5 pct V to 325°C for 12.7 pct V. IN the transition series of the periodic table, the six elements that have a body-centered cubic structure at all temperatures, namely chromium, vanadium, molybdenum, columbium, tungsten, and tantalum, fulfill the conditions required for the existence of complete series of solid solutions with the high temperature (ß) form of titanium. Up to the present time, complete solubility at temperatures above the a to ß transformation of titanium has been observed in the systems Ti-MO,1,2 Ti-Cb,2 Ti-W,³ and Ti-Ta.³ The two remaining elements, vanadium and chromium, have atomic diameters which are not as near that of titanium as the atomic diameters of the four other elements. Both are smaller than titanium and the difference, expressed in percentage of the titanium atomic diameter, is 12.3 pct for chromium and 8.2 pct for vanadium. On this basis, the least favorable conditions for solid-solution formation are therefore encountered in the Ti-Cr system. The early work on the Ti-Cr system4 revealed that up to about 1100°C the solubility of chromium in ß titanium is limited, and an intermetallic phase exists near the stoichiometric composition TiCr2. It was found later&apos; that a continuous series of solid solutions extends across the diagram at higher temperatures, and TiCr2 forms by solid state reaction. It became apparent therefore that complete solubility would also be present in the Ti-V system. The present investigation confirms this possibility. The iodide-refined titanium used in this investigation was purchased from the New Jersey Zinc Co., New York. According to the manufacturer, a typical analysis of this product is 0.0065 pct Mn, 0.0022 pct Fe, 0.0015 pct Cu, and 0.0042 pct Pb. The Vickers hardness number (10 kg load) of the crystalline bar varies between 55 and 80. The vanadium metal was purchased from the Westinghouse Electric Corp., Lamp Div., Bloomfield, N. J. The purity of this metal is probably above 99 pct V. The oxygen content must have been quite low, since a bar about 1/4 in. square could be cold rolled into a ribbon 0.020 in. thick. To prepare the various alloys on the titanium-rich side of the diagram, the titanium rod was machined into cups 1 cm in diam and about 1.5 cm high. Pieces of vanadium, of the proper weight, were cut from the square bars and placed within the cups prior to melting. On the vanadium-rich end of the diagram, single pieces of the metals, in the proper weight pro-

Jan 1, 1953

By H. D. Kessler, F. A. Crossley, J. J. Rausch

The titanium-rich corner of the system Ti-AI-V has been studied to determine the phase relationships in the temperature interval 600° to 1200°C. Metallographic examination of long time isothermally annealed specimens was the principal method of investigation. TWENTY-SIX alloys in the region 1 to 22 pct A1 and 2 to 11 pct V, and the temperature range 600° to 1200°C, were studied as part of a program on phase relationships and transformation processes of titanium alloy systems. Experimental Procedure Preparation of Alloys—Materials used in the preparation of alloys were high purity Bureau of Mines sponge titanium (103 Bhn), 99.7 pct pure V chips obtained from the Electro Metallurgical Div., union Carbide and Carbon carp., and 99.71 pet pure A1 in the form of granulated shot from Aluminum cO. Of The alloy ingots, weighing l5 g, were melted in a nonconsumable tungsten electrode arc furnace un-

Jan 1, 1957

Executive Committee, Board of Directors C E Reistle, Jr, Chairman, H DeWitt Smith, Vice-Chairman, T B Counselman, Grover Holt, A W Thornton Finance Committee, Board of Directors Andrew Fletcher, Chairman, R B Caples, C R Dodson Investments Erle V Daveler, &apos;57, Chairman, Henry Krumb, &apos;59, John E Warren, &apos;57, G F Moulton, ex officio as Treasurer, Andrew Fletcher, ex officio as Chairman, Fi¬nance Committee Endowment W W Mein, Jr, Chairman, N G Alford, E V Daveler, W J Coulter, J V N Dorr, R B Gilmore, J B Haffner, 0 H Johnson, Henry Krumb, D H McLaughlin, J R McMillan, J B Morrow, L F Reinartz, Wilfred Sykes, C E Weed Honorary Memberships Andrew Fletcher, Chairman, L F Reinartz and H DeWitt Smith, ex officio as Past Presidents, C E Reistle, Jr , ex officio as President, M L Rai¬der, &apos;60, Henry Krumb, &apos;58, D H McLaughlin, &apos;57, P D Merica, &apos;59

Jan 1, 1956

(Members are urged to send in for this column any notes of interest concerning themselves or their fellow-members.) Members and guests who registered at Institute headquarters during .the period Jan. 10 to Feb. 10, 1915: N. H. Emmons, 2d, Dover, Mass. R. 0. Hocking, Redruth, England. Paul W. Gaebelein, Cornucopia, Ore. G. H. Carnahan, New York, N. Y. H. D. Kinney, Easton, Pa. W. A. Wilson, Salt Lake City, Utah. W. D. McDougall, New York, N. Y. H. V. Winchell, Minneapolis, Minn. Kirby Thomas, New York, N. Y. Mrs. H. V. Winchell, Minneapolis, Minn. V. T. Lawshe, Newark, N. J. Keijiro Nishio, Tokyo, Japan. Henry S. Stebbins, who has been connected with the firm of Oglebay, Norton & Co., Cleveland, since 1892, has resigned to accept a position with M. A. Hanna & Co. of the same city. E. L. Newhouse has been chosen First Vice-President of the American Smelting & Refining Co. in place of the late Barton Sewell.

Jan 3, 1915

By E. O. Wagner, V. F. Parry, J. B. Goodman

C. P. HEINER*—If you take out 35 pct of the total weight of the coal in the form of moisture, would that be about what it was in the case of North Dakota lignites ? V. F. PARRY (authors&apos; reply)—That is about it. C. P. HEINER—That will be about a 35 pct loss and the final product will be about 11,000 Btu? V. F. PARRY—That is right. The heating value of the dried lignite is 10,000 to 11,000 Btu. C. P. HEINER—And the thought is not, then, to produce a commercial coal with that heavy loss, but to make other products—that is, synthetic fuel base, is that it? V. F. PARRY—The principal thought is to upgrade the coal, making it a more favorable raw material for industrial purposes, both for shipment and direct use. You see, the trouble in these lignites is that their moisture penalizes their

Jan 1, 1950

By AIME AIME

THE 122d meeting of the Institute was held in the Lake. Superior Copper and Iron Country Aug. 20 to Sept. 3, 1920 with an approximate registration of 1100 members and guests. This is the &apos;first visit of, the Institute to this vicinity since 1904 although previously it held meetings there every six or, seven years. &apos;The eastern party assembled at Buffalo and sailed on the S. S. "Tionesta ". on Friday morning, Aug. 20, arriving at Houghton, Mich., Monday, Aug. 23. En route stops were made at Detroit, where sightseeing auto trips were taken, and at Mackinac Island, where a short stop permitted a visit to the picturesque and historic Fort Mackinac.

Jan 1, 1920

By George W. Friesen

This paper presents the historical trend and de- fines the causes of drilling cost escalation in the Gulf of Mexico during the 1970&apos;s. The three major components of escalation are: 1) inflation, 2) supply-demand imbalance (demand pull) and 3) decreases in drilling efficiency. The decade was divided into three periods. During each period one component of escalation was responsible for most of the rise in costs. From 1970 through 1973 only inflation pushed costs upward. During 1974 and 1975 a supply- demand imbalance caused most of the escalation. Since 1975, decreases in drilling efficiency have produced the major component of escalation. During any one year or period of years, the sum of the three components will give the total escalation rate. The reasons why different components contribute more toward escalation during certain years than others are shown by following the timing of oil and gas price increases, the overall quality of the acreage offered each year in offshore lease sales and the resulting drilling activity.

Jan 1, 1982

THE opening session was held on Tuesday evening, February 17th, in the house of the American Society of Civil Engineers. The President of the Institute, Mr. E. B. Coxe, after a few introductory remarks, congratulating the members on the general prosperity in all the branches of the professions and manufactures represented by the Institute, called on Mr. E. F. Loiseau, of Philadelphia, for the first paper, On the Successful Manufacture of Compressed Fuel at Port Richmond, Philadelphia. Professor Prime called attention to the fact that the work of the United States Testing Board had been left unfinished at a point when valuable results had just been reached, and offered the following resolutions: WHEREAS, The American Institute of Mining Engineers has seen with regret that the work of the United States Testing Board has been suspended through the lack of an appropriation by Congress, which appropriation dues not seem likely to be renewed, and WHEREAS, It seems most important to the vital interests of our iron and steel manufactures that the experiments commenced by the United States Testing Board should be carried to successful completion ; Resolved, That a committee of three be appointed, to act with a like, committee to he appointed by the American Society of Civil Engineers, to carry out to completion the work commenced by the United States Testing Board. Resolved, That the American Society of Civil Engineers be requested to cooperate with this society by the appointment of a like committee. Resolved, That the committee have authority to request, in the name of the American Institute of Mining Engineers, contributions to a fund to be devoted to the completion of the experiments aforesaid. Resolved, That the Council of this Institute be authorized, whenever requested by the committee so appointed, to petition Congress for the free use of the testing machine at the United States Arsenal at Watertown. Resolved, That a committee be appointed by the President, to select the afore-said committee of experts. Resolved, That the President of the Institute have authority to fill any vacancies which may occur in the committee. The resolutions were unanimously adopted, and President Coxe appointed the following committee in accordance with the resolutions : Messrs. A. L. Holley, James Park, Jr., and J. F. Holloway. The President also appointed Messrs. Heinrich, Mickley, and Spils-

Jan 1, 1880

SECTION I PAGE PAGE Bulletins Wanted v Local Section News xv St. Louis Meeting v Affiliated Student Society Notes.. xviii National Engineering Societies in California&apos;s Mineral Resources National Service..: vii ? for War Purposes xix Members in Officers Reserve Corps xi Forthcoming Meetings xx Resolution by Military Engineering ? Library xxi Committee xi Membership. :: xxiv Personal :.. xii Biographical Notice of David H. Employment xiv Browne xliv Alaska Mining and Engineering Institute Committees xlvii Society xv Officers and Directors liv

Jan 6, 1917

Resistant Tape A new oil-resistant tape for rapid insulation build-up on splices in large power cables has been announced by Minnesota Mining & Mfg. Co. Designated Scotch brand electrical tape No. 25 is made of synthetic rubber providing greater dielectric strength and resistance to high temperatures. The chemical-resistant qualities of the tape make it suitable for use in oil drilling, mining and underground [ ] cable operations, while the 40-mil thickness and extreme stretch (1500 pct breaking point) make possible smooth insulation wraps on irregular surfaces. Dielectric strength is 15,000 v and 10,000 v at 500 pct elongation. It has an electrolytic corrosion factor of 1.0 and an insulation resistance of 100,000 megohms. Circle No. 1 Hydra-Lift The Pitman Mfg. Co. announces that is now has in production a new model of the Pitman hydra-lift, recently-developed crane with hydraulically-powered boom that can be mounted on the frame of any truck, 1 ½ tons or larger. According to the manufacturer, the new model hydralift model B features a variety of improvements over the original production model, introduced late in 1950. Changes incorporated in the new model, according to officials, not only have resulted in improved crane, but also have given the unit a new profile which distinguishes it sharply from the original model. The two chief improvements in the new model are: a big increase in the unit&apos;s safety margin and the fact that it is now shipped almost completely preassembled, cutting the time and cost of installation. Rated capacities of the hydra-lift are based on the tipping factor of a 1 1/2 ton truck, with outriggers down, and thus have not been increased. Circle No. 2

Jan 1, 1952

By T. K. Perkins, W. W. Krech

Jan 1, 1969

By Donald B. Gillies

TO me a graduating class of engineers constitutes one &apos; of the finest inspirations I can imagine. You have finished your four- year scholastic career and are starting out in competition with thou- sands of other young men from other universities to make your mark. Be- cause of your training you men are such an essential part of our present- day civilization that a great weight of responsibility rests on your shoulders, especially at this time, for this is an engineering era. Today, it is the engineer who dreams the dreams and makes our civilization better. It&apos;s the engineer who carries those dreams into realization and fulfillment. No matter where we go in business and industry, we find- engineers in key positions, charged with great responsibilities.

Jan 1, 1939

By Fredrick C. Kruger

Introduction This surprisingly little-known group of minerals, the nonmetallics, so-called for their lack of metallic luster, is the largest group of the mineral kingdom, and cinstitutes perhaps 75 percent of all mineral species. For the most part, these minerals are compounds of the common acids, oxides, hydroxides, and two elements, carbon and sulfur. The list of the non- metallic minerals, therefore, is very long. It includes the borates, carbonates, chlorides, fluorides, nitrates, phosphates, silicates, sulfates, and less commonly, arsenates, chromates, molybdates, suliides, tungstates, and vanadates, the latter groups, and many of the oxides, being sought principally for their metal content. Those nonmetallics used commercially are generally called the industrial minerals, although in addition this term also includes a considerable group of rocks. The list of industrial minerals and rocks is continually growing as new uses are found, and it now numbers over 300 commodities. The industrial minerals industry has developed since about 1920. There- fore, the development has been fast, and it has been more or less parallel with the development of the art of minerals beneficiation. General Discussion of the Group This group is so heterogeneous that it has defied logical, or widely accepted, classification, whether by origin, composition, or end use, and perhaps for this reason the industrial minerals generally have received short shrift in both teaching and research. Except for those involved with asbestos, cement, fertilizers, gypsum, salt, sand and gravel, few large companies have deigned to enter the field, and consequently most industrial minerals have been developed for the most part by the small operators or entrepreneurs. Yet surprisingly, except for one war year, the nonmetallics have always surpassed the metals in value and tonnage (Fig. 1). One main characteristic that most of the nonmetallics have in common is direct sensitivity to labor and transportation. In other words they are characterized by large bulk and low-unit value, and hence have what might be termed a "place value".

Jan 1, 1971

Jan 1, 1886

By W. L. Honnold

AS BOTH South Africa and diamond mining are unfamiliar subjects it seems best that on such an occasion as this I should endeavor to reflect the atmosphere of the place and to picture the mines from an industrial rather than from a technical standpoint and, because of long absence, my remarks must necessarily be sketchy and in some particulars not up to date. The preferable route to South Africa is via England, direct steamers from America being inferior as to service and effecting no saving of time. The newer boats are of about 20,000 tons capacity and very comfortable. Seventeen days are required for the voyage and only one stop is made-that at the island of Madiera, three days out. Between Southampton, the port of departure, and Madiera the weather may be warm or cold and the

Jan 1, 1925

By J. Armanet

THREE MINING colleges are maintained in France; the École Nationale Supérieure des Mines, of Paris; École Nationale Supérieure des Mines, of Saint Etienne; and the École Supérieure de la Metallurgie et des Mines at Nancy. Besides graduates of these schools, a few graduates of the École Centrale des Arts et MIanufactures and of the École Polytechnique are employed as ]nine managers or engineers; however, most of the latter have taken a graduate course at one of the mining schools.

Jan 1, 1939

By D. Harrington

ANNUAL or necessary inspections and investigations of coal mines for various purposes were made possible through the Federal Coal Mine Inspection Act of May 7, 1941, which authorized entry to the Secretary of the Interior through the Bureau of Mines. Primary object of these inspections is to obtain information pertaining to health and safety conditions. Among the purposes for which the data are to be used, are annual reports to Congress, the publication of inspection reports, and the compilation and publication of statistics. The act states that inspections and investigations shall be made by employees of the Bureau of Mines, who shall co-operate with other bureaus of the U. S. Department of the Interior, as well as with the official mine-inspection, safety cr health agencies of the several states and territories. The act specifies that a coal-mine inspector shall have "the basic qualifica-

Jan 1, 1946

By Leon Borgman, Michael P. Lipkewich

Orebodies at or near the surface are generally amenable to open pit mining. The development of a mining program involves designing an ultimate pit and a production schedule. This pit maximizes total profit while the production schedule maximize6 the present value of the property. Optimum pit limits can be approximated by two-and three-dimensional numerical techniques. These techniques presuppose that the mineralized area has been sufficiently sampled to allow a reasonably accurate prediction of grade at any spatial location.

Jan 1, 1969

By Carl Lee

CHICAGO in the last week of June fulfilled all its promises to the visiting engineers except one. This holds true with respect to the activities of the Regional Meeting of the A. I. M. E. in particular and of Engineers&apos; Week in general. No one expected to find much of the beautiful in the outward aspects of the Fair-the Century of Progress Exposition, to be more formal; but they expected novelty, color, and startling lighting effects at night, and they were in no sense disappointed. It has been said that the architecture is a portent of the style of the buildings of the future; most who have seen the Fair hope that this forecast will prove inaccurate. As to the exhibits themselves, they are splendid. They are in keeping with the theme of the Exposition-a Century of Progress in science, in engineering, in the industries based upon them. No attempt will be made here even to suggest the exhibits that are most interesting. There are plenty for every one; and any member of the Institute who has the opportunity should by all means visit Chicago before the end of October.

Jan 1, 1933