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Jan 1, 1967

By Nicholas J. Grant, H. C. Chang

Microscopic observations during creep tests were made on AI-20 pet Zn, 80 pet Ni-20 pet Cr, and 25 and 3S aluminum specimens. All these materials failed in an inter-crystalline manner under certain stress and temperature conditions. Particular atten-tion was given to the initiation and propagation of intercrystalline cracks in coarsegrained AI-20 pct Zn specimens. The geometry of the grains and grain boundaries in these specimens was known before the tests. On the basis of the observations and a knowledge of the interaction between grains and grain boundaries, a mechanism of intercrystalline fracture and propagation of the fracture has been proposed. METAL, and alloy fracture occurs essentially in two ways: transcrystalline and intemrystalline. In the past most of the work done in this field was centered on the determination of stress criteria for fracture. The specimens used for these studies were tested under varying conditions of stress state, temperature, and strain rate. Unfortunately, very little attention was given to the initiation and propagation of the fracture, whereas the nature of fracture was examined closely only after failure. Several extensive reviews of these studies have been published by Orowan, Smith, Barrett, and Petch.1, 4 It is well known that a material which exhibits a ductile and transcrystalline fracture can be made to exhibit a brittle and intercrystalline fracture by modifying its composition and by heat treatment. This modification may or may not result in microscopically observable precipitation in the grain boundaries." In the creep of any one alloy the transition of transcrystalline to intercrystalline fracture is a function of stress, strain rate, and temperature." The tendency for intercrystalline fracture to occur increases as the strain rate decreases and the testing temperature increases. Extensive work on high purity aluminum (99.995 pet) under creep conditions showed the importance of the interaction between grains and grain boundaries, and the different responses of grain and grain boundaries to the variables: stress, strain rate, and temperature.7, 8 It was also shown that grain boundary deformation necessarily has to be accommodated in the grains by various deformation means as. for example, fold formation. The type of fracture resulting from the creep of high purity aluminum was invariably found to be transcrystalline. On the other hand, 2S and 3s aluminum were, under certain conditions, found to fracture in an intercrystalline manner." One reason given for this was that the grains could accommodate to a lesser extent the deformation of the grain boundaries.19 It was decided to examine this line of reasoning in greater detail and to investigate the particular interactions between grains and grain boundaries that result in the incidence and progression of inter-ct,ystalline fracture. It is also the purpose of this paper to show where and how intercrystalline cracks start and how they propagate to result in fracture. Several alloys—Al-20 pct Zn, 80 pet Ni-20 pet Cr, 2S and 3s aluminum-— were used for this study, but attention was paid mainly to the behavior of an A1-20 pet Zn alloy, since its general creep behavior has been established." From the results of this study a mechanism of intercrystalline fracture is proposed. Experimental Procedure The experimental procedure was similar to that used in previous work and has been detailed elsewhere.' Two parallel flat surfaces were milled from an originally round specimen, giving a gage portion which was 1x0.09X0.17 in. Some round specimens, 1/4 in. round by 1 in., were also tested. The A1-20 pet Zn specimens. which were annealed at 1030°F for 24 hr, showed two to four grains across the width of the test bar, and most of the grains occupied the whole thickness of the specimenu. Before some of the specimens were subjected to creep, the grain arrangement was mapped out in a development drawing, Fig. 1. The initiation and

Jan 1, 1957

By William Metcalf

It is the object of this paper to oppose unnecessary changes, and the introduction of new and confusing terms. From the earliest times of which we have ally record on the subject, iron has been divided into general classes. Whether iron was first known in the form of wrought iron or of steel, is a matter of no importance; but at the time when cast iron first became a prominent article of commerce, wrought iron and steel were old products— steel, at that time, being generally made from wrought iron by the process of cementation. As steel was then properly defined as iron containing more carbon than wrought iron, so cast iron was appropriately defined as iron containing more carbon than steel. Until the year 1776, when Huntsman first began the manufacture of a new kind of iron by melting wrought iron and steel in crucibles, the above definitions were all that could be desired. At first, probably, owing to imperfect appliances, only a highly carburized iron was melted in crucibles, and this led to its being called cast steel. If our ancestors had found a name for this material not involving the use of the word steel, we would have been saved the trouble of the present discussion. As the arts developed, new uses were found for steel, and the products of the crucible were varied, until at the present day it is quite common to find steel containing no more carbon than average wrought iron, and other steel containing nearly or quite as much carbon as some cast iron. All of these various products of the crucible have retained, or received, the name cast steel, usually abbreviated to the simple word steel, without caus-ing any confusion among producers or consumers in regard to terms or their meaning. In 1865, twenty-one years ago, the Bessemer process was introduced ; this was followed in a few years by the Siemens-Martin process, and the products of both were at once, and have ever since been, called steel, from the fact that they were identical in chemical and physical properties with crucible cast steel. At the present time, then, we have three subdivisions of cast steel, viz.: Crucible cast steel, Bessemer cast steel, and Siemens-Martin,

By James A. Todd

Use of AN-FO in underground operations has greatly reduced the cost of primary explosives. AN-FO is also less sensitive than conventional dynamites, and when properly used, is safer. Maximum safety in the use of AN-FO, however, requires an understanding of potential hazards from toxic fumes as well as static electricity developed in pneumatic loading. Safe limits and guides have been established to permit most operations to pneumatically load holes that are bottom primed with electric blasting caps, but the toxic fume hazard is less widely understood. During 1959-1960 Du Pont cooperated with the U.S. Bureau of Mines to study the toxic fumes produced by prilled ammonium nitrate-NO. 2 fuel oil mixtures. The conclusions from this work were that oxygen balanced AN-FO, when thoroughly mixed, well primed and well confined in dry holes, produces no greater amounts of toxic fumes than conventional dynamites rated Class I by the Institute of Makers of Explosives. The study also showed, however, that any deviation from these guides tends to increase significantly the quantity of toxic fumes produced. This work was reported by the Bureau of International Symposium on Mining Research at Rolla, Mo., in February 1961.'

Jan 4, 1963

By S. G. Lasky

Abraham Lincoln is reputed to have said that if you want to chart a course to some destination, you have to know where you are starting from. In this instance we have to define our starting point in a double manner: 1) What was the theoretical basis of the Paley predictions? 2) What actually did the Commission predict, so that we can see how the predictions have worked out up to now as a basis for considering how they may have to be changed.

Jan 3, 1960

By T. T. Read

TWO papers on health and safety were given Thursday afternoon when a joint session of the Health and Safety Committee and the Mining Methods Committee was held. T. T. Read presided and the first paper, on ventilation at Climax, was presented by the author, L. H. Glanville. In the subsequent discussion by Cloyd M. Smith, P. B. Bucky, B. F. Tillson, D. F. Haley, J. L. G. Weysser, and others a number of interesting points not covered by the paper, which appears in full in the January Mining Technology, were brought out. Ventilation troubles in mines so often hinge on the air being too hot and damp that it was interesting to hear of one where it is frequently too cold and too dry.

Jan 1, 1943

By F. G. Cottrell

About a year and a half ago, at the San Francisco meeting of the American Chemical Society, in connection with the excursions to local smelting-works, I had occasion to show some lantern-slides illustrating the recent commercial development of electrical methods for precipitating the suspended matter from smelter-smoke, the underlying phenomena of which were clearly brought to the attention of the technical public by Sir Oliver Lodge as long ago as 1884. In the .Journal of Industrial and Engineering Chemistry, August, 1911, most of these views were reproduced, together with an account of the work from its beginning up to July, 1911. To-day I wish particularly to show you some of the further developments of the work since that time; but in order to make these clear they will be prefaced by a brief abstract of the article above referred to. The removal of suspended particles, from gases, by the aid of electric discharges is by no means a new idea. As early as 1824 we find it suggested by Hohlfeld ' as a means of suppressing ordinary smoke, and again a quarter of a century later by Guitard.2 These suggestions, which do not seem to have stimulated any practical study of the question, were soon entirely forgotten, and only brought to light again by Sir Oliver Lodge: many years after he himself had independently rediscovered the same phenomena and brought them to public attention4 in a lecture before the Liverpool Section of the So-

Jan 1, 1913

A special meeting of the Alaska Mining and Engineering society, held at Perseverance Mine of the Alaska Gastineau Mining Co. on Mar. 17, 1017, was attended by 46 members and about 80 guests, among whom were members of the Alaska Territorial Legislature. After an interesting trip through the mine in the afternoon, the members and guests assembled for dinner at the Perseverance Dining Room. After the dinner G. T. Jackson, assistant manager of the company, as president of the society, called the meeting to order. After the reading of the minutes, he welcomed the guests and then gave a short history of Perseverance Mine. B. L. Thane, manager of the company, briefly out-lined its general organization. The following papers were read-by members of the society and members of the staff of the Perseverance Mine: "The Organization of the Mine Staff and the Methods of Mining," by B. B. Nieding, Mine Supt.; "Tramming Equipment and Costs," by R. R. Van Valkenburgh; "The Surveying of the Mine," by R. L. Healey, Mine Engineer; "The Electrical Equipment of the Mine," by W. S. Pullen, Supt., of Power Supply; "The System of Mine Accounting, "by E. J. Doherty, Mine Accountant; and "The Mine Buildings," by D: J. Argall, Asst: Mine Supt. M. T. Tolch, Transportation Supt., described briefly the general transportation of the ore to the mill and the equipment used.

Jan 6, 1917

By William B. Heroy

LOOKING back over the industrial and commercial progress of the United States during the last half century the outstanding influence has been the growth of the use of the fluid fuels, petroleum and natural gas. At the turn of the century these fuels supplied only 8 per cent of the energy requirements of the nation. Last year nearly 45 per cent of our heat and power supply were derived from these fuels. These figures are merely statistical reflections of the fundamental change in our national economy which has affected, in so many amazing ways, the life of this generation. The factors which have caused this change are still operative. The trend which has thus been established still continues and growth in the use of these fuels is, in all probability, still well below the peak, both for this country and for other parts of the world. Two great wars have not essentially changed this basic trend; if anything they have served to accelerate it. World War II did not alone increase our requirements for liquid fuels; it demonstrated the absolute essentially of petroleum resources to our national security. Petroleum is no longer just an important factor in our national standard of living; it is the most important single element in our national defence-

Jan 1, 1946

By R. J. Pfister

The development of a water-input profile instrument based on the introduction of brine and fresh water into an input well with the electrical location of, the boundary developed between them is reported. Two methods are available in the use of this instrument to measure the foot by foot water-intake rates of the various sand strata: the moving boundary method in which variable well bore diameters can be determined and/or cancelled out and the constant boundary method. The type of results obtained and the relative advantages of each of these methods are described in detail. Representative data are included covering the use of this instrument in experiments involving selective acidizing, selective plugging, and selective shooting. In such experiments, this instrument has been used to diagnose the unfavorable distribution of water intake in input wells and also to determine the effectiveness of the resultant treatments. The data included also serve to illustrate the type of problems which can be studied with this technique. Introduction For ten years or perhaps longer a number of progressive water-flood operators have felt the need for some to to measure the foot by foot water-intake rates of various strata in water-injection wells. The primary need is to diagnose unfavorable water distribution in various strata and to evaluate the effectiveness of the corrective measures such as selective acidizing, selective plugging, and selective shooting. Previously described methods for obtaining this type of data were not considered entirely adequate.l,2 The profile equipment described in this paper embodies the separate introduction of brine and fresh water into the well at carefully measured and controlled rates and the electrical location of a sharp boundary developed between these fluids. At present this instrument is a research tool of value in determining the effect of various well treatments on an individual sand strata. lts primary use has been on wells in which different sections require different treatments (e.g., wells with an open sand to be plugged and a tight sand to be acidized)- It has, thus, made possible the determination of a rearrangement of the water intake of a well. The instrument can also be used to direct the treating material into a given zone. In completing a well the less permeable sands are shot more heavily with nitroglycerine in order to equalize the water intake between the permeable and less permeable sands. The extent to which such corrective shooting has been successful Can be determined by a water-input profile. The combined profile and well-bore diameters should also provide a method for determining the direction and effect of various selective shooting techniques. Equipment The essentials of the water-input profile technique for measuring the intake per foot of individual sand strata are the injection of a nonconducting fluid, water, at the top of the well and a conducting fluid, brine, through a separate string of

Jan 1, 1948

By R. J. Pfister

The development of a water-input profile instrument based on the introduction of brine and fresh water into an input well with the electrical location of, the boundary developed between them is reported. Two methods are available in the use of this instrument to measure the foot by foot water-intake rates of the various sand strata: the moving boundary method in which variable well bore diameters can be determined and/or cancelled out and the constant boundary method. The type of results obtained and the relative advantages of each of these methods are described in detail. Representative data are included covering the use of this instrument in experiments involving selective acidizing, selective plugging, and selective shooting. In such experiments, this instrument has been used to diagnose the unfavorable distribution of water intake in input wells and also to determine the effectiveness of the resultant treatments. The data included also serve to illustrate the type of problems which can be studied with this technique. Introduction For ten years or perhaps longer a number of progressive water-flood operators have felt the need for some to to measure the foot by foot water-intake rates of various strata in water-injection wells. The primary need is to diagnose unfavorable water distribution in various strata and to evaluate the effectiveness of the corrective measures such as selective acidizing, selective plugging, and selective shooting. Previously described methods for obtaining this type of data were not considered entirely adequate.l,2 The profile equipment described in this paper embodies the separate introduction of brine and fresh water into the well at carefully measured and controlled rates and the electrical location of a sharp boundary developed between these fluids. At present this instrument is a research tool of value in determining the effect of various well treatments on an individual sand strata. lts primary use has been on wells in which different sections require different treatments (e.g., wells with an open sand to be plugged and a tight sand to be acidized)- It has, thus, made possible the determination of a rearrangement of the water intake of a well. The instrument can also be used to direct the treating material into a given zone. In completing a well the less permeable sands are shot more heavily with nitroglycerine in order to equalize the water intake between the permeable and less permeable sands. The extent to which such corrective shooting has been successful Can be determined by a water-input profile. The combined profile and well-bore diameters should also provide a method for determining the direction and effect of various selective shooting techniques. Equipment The essentials of the water-input profile technique for measuring the intake per foot of individual sand strata are the injection of a nonconducting fluid, water, at the top of the well and a conducting fluid, brine, through a separate string of

Jan 1, 1948

By D. R. de Fontaine

By computing the values of the resolved shear stress for a great many orientations of the tensile axis on all 12 (111) <110> slip systems, Taylor and Elam&apos; were able to map out a stereogram of slip systems, given here, Fig. 1, in Diehl&apos;s notation (see, for example Hauser and Jackson&apos;). The purpose of the present note is to derive such a stereogram by mathematical reasoning and to give a simple method of defining the system with highest resolved shear stress for any direction of the tensile axis, thereby eliminating tedious computation of the Schmid factor. Let the tensile axis, of direction cosines [xyz], make the angles 0 and relative to the slip plane normal [HKL] and the slip direction [hkl] respectively. Fig. 2 shows a simple cubic cell whose edges define a Cartesian coordinate system. Let A be a unit vector of origin 0 supported by the tensile axis. Its end point [xyz] then lies on a sphere of unit radius, on the positive hemisphere of which the planes z = 0, x = y, y = z limit the so called primitive triangle of a standard [loo] stereographic projection. For any point of this triangle, the following hold: 0«2 «y *sx « 1 [l] Now, for given [xpz], the most highly stressed system will be the one for which the following expression of the Schmid factor has the largest possible value: (HKL) belonging to the form (111) and [hkl] to the form <110>, the denominator on the right hand side of Eq. [2] is equal to 1.fi.a. The unknowns H, ... h, . . . can now be determined by correctly distributing +1 and -1 to H, K, L, and +1, -1,O to h,k, 1 giving the numerator of Eq. [2] its greatest positive value (the angles 0 and cpare chosen acute) subject to the condition: Hh+Kk+Ll = 0 [3] since the slip direction must lie in the slip plane. Condition [3] can be satisfied only by having one of its terms vanish and the other two equal to +1 and -1. Taking the case of the tensile axis lying in the primitive triangle, x2y, z and therefore Hh will be chosen equal to +1 with H = h = +1 in order to retain a maximum of + signs. There remain two alternatives: either 1 = 0 or k = 0. 1) take 2 = 0 Then Kk = -1 and the numerator of [2] becomes: Retaining a maximum of + signs gives L = k = +1 and becomes: 2) take k = 0 Then L1 = -1and, likewise, the numerator of [2] becomes: xz - z2 + xy + yz [5] But the difference [5] - [4] can be written: (y - z)(x+y +z) [6] positive or zero by virtue of [I]. If [6] is positive (y > z), then the largest possible value for the numerator of [2] for any xyz inside the primitive triangle is given by [5], i.e., for: That is to say, the active slip system corresponding to an orientat:~on of the tensile axis inside the primitive triangle is:

Jan 1, 1962

Jan 1, 1962

By W. C. Winegard, J. R. Carruthers, A. Plumtree, L. R. Morris

The unidirectional solidification of dendrites containing central twin planes was studied in A1-Ti alloys. Once nucleated, the twinned dendrites are a Twore ejficient form for solute redistribution and therefore grow in preference to the normal columnar dendvites. Comparison of these twinned dendrites to adjacent colunmar dendrites by means of decanting experinzents and electron-probe rnicvoarmlysis indicates that these special dendrites grow with less undercooling than normal dendrites. These findings are further supported by the effect of forced convection on the dendrite morphologies. COMMERCIAL semicontinuous cast ingots of most aluminum alloys frequently exhibit large grains which appear to be composed of hundreds of parallel, continuous, thin lamellae. This structure has been termed "basaltic",&apos; "fiederkristall", or, commonly, "feathery grain". The lamellae are &apos;about 100 p thick, several inches long, and each lamella contains a central (111) coherent twin boundary. The feathery grain has been reported to have a (112) direction2 and a (110) direction4 in the twin plane parallel to the casting direction, in contrast with the usual columnar structure where a (100) direction predominates. Aust et uZ.~ proposed that the twin boundaries were growth twins nucleated by stacking faults on the octahedral planes. chalmers6 has suggested that feathery grain may grow by a re-entrant edge mechanism, as proposed by wagner7 for twinned dendritic growth in germanium. Cahn et ~1.~ have concluded that the occurrence of feathery grain is evidence of some form of lateral layer growth rather than the atomically continuous growth normally observed in metals. The postulates by Chalmers and Cahn would seem to be contradicted by the work of Nakao~"&apos; who showed that feathery grain only occurs when growth rates are high and the aluminum contains some solute. Specifically, Nakao found that in order to obtain feathery grain, in small castings solidified unidirec-tionally upward, the rate of growth must be above 2.4 cm per min and a critical solute concentration must be present. Below this solute concentration the grain structure was totally columnar. The critical solute concentration was found to be approximately: 0.04 wt pct Ti, 2 wt pct Cu or Mg, and 8 wt pct Zn. As pointed out by Chalmers it is not obvious why a twin-plane re-entrant edge mechanism would occur in aluminum which is thought to have a diffuse solid-liquid interface. The present experiments were undertaken to determine the growth mechanisms in- volved and to study the solute segregation in more detail. EXPERIMENTAL PROCEDURES Alloys ranging in composition from 0.05 to 0.23 wt pct Ti* were prepared from 99.9 pct pure Ti and 99.993 pct pure Al. Two-hundred-gram samples of A1-Ti binary alloys were solidified unidirectionally and vertically upward from a water-cooled copper base, in a heated insulated mold. The 1-in.-diam, 6-in.-length mold was made of Marinite (manufactured by Johns-Manville Co.). The mold was attached to a 24-in. pivoted arm such that by dropping a weight the mold was rotated 180 deg, throwing the liquid metal from the solid. In this way, the solid-liquid interface was revealed by decanting. A sketch of the decanting mold is shown in Fig. 1. The alloy was poured into the mold at temperatures ranging from 680" to 750°C, partially solidified by water cooling from the base, and decanted after a measured time interval. Growth rates for each metal-pouring temperature were calculated from solidification-time vs length solidified curves. Temperature gradients in the melt were measured using four No. 34 gage thermocouples which protruded into the mold cavity. Grain orientations were determined by X-ray diffraction using Laue back-reflection techniques. Grain substructures were examined metallographically, using polarized light, by applying a thin epitaxial anodic film to polished sections after the method of Hone and pearson." Titanium micro segregation was measured by electron-probe microanalysis using a NORELCO AMR/~ with a mica crystal and proportional-flow counter. Several of the cast samples exhibited feathery and columnar dendrites growing in the same direction and

Jan 1, 1967

Jan 1, 1968

By L. F. Mashburn, T. J. Ferree

A Reichert cone concentrator was installed in an aggregate plant circuit to recover the extremely fine "flour gold" known to exist in the deposit. The gold content of the bank- run gravels averages about 0.1 g/t-about $1.29/t, based upon $12.86/g ($400 per oz) gold. The fineness of the gold averages between 950 and 960. The Reichert cone, in conjunction with a conventional shaking table, recovers in excess of 85% of the gold. A screen analysis of the gold particles shows 44.1 % is - 74pm (-200 mesh) in size. The plant operates with a two-man crew.

Jan 1, 1983

By Lewis Stockett

During the year 1903, a building having machinery corresponding to ail anthracite-coal breaker was erected at the town of Stockett, Cascade county, Mont., for the purpose of breaking-up and cleaning bituminous coal. The coal is mined from a vein of the Kootenai group of the Lower Cretaceous measures having the following section: The vein is nearly horizontal in position, and each bench differs in quality as shown in Table I.

Jan 1, 1905

Jan 1, 1970

By R. P. Smith

In 1937 the employees of the Hollinger Consolidated Gold Mines Ltd.. at Timmins. Ont., Canada, approached organized medicine for a plan to provide themselves and their families with a complete medical service including hospitalization. This approach was made because of two conditions: (1) the necessity for some organization whereby contributions could be made in instalments to offset the sudden and large expense connected with illness for which the average employee is not prepared, and (2) the need for a more cohesive quality of service to replace a contract practice then in vogue, which did not take care of the employee&apos;s family or dependents. In different parts of the United States and Canada similar plans were in force, not only for employed groups but for numbers of people in circumscribed areas. In Europe different countries had adopted various forms of health insurance plans. It then was no surprise that these employees as a group should ask for some similar plan. With the cooperation of the management, a plan was instituted. The plan has one object only—the provision of medical services, including the accessory services such as hospitaliza-tion, X-rays, nursing, and necessary drugs and medicines. It is not concerned with cash benefits, sickness and accident payments, or any form of monetary return as the result of illness, but is simply an organization to provide medical services and pay for them from a central fund. It is a nonprofit organization and the only shareholders are the employees and their families who contribute and who in turn receive services. The Hollinger plan is limited to the employees of the Hollinger mine, who live in Timmins and the immediate vicinity. At first, the membership was voluntary. In the third year, it was made a condition of employment, with the proviso that at the end of any Association financial year an employee may withdraw if he wishes to do so. After withdrawal, he cannot again become a member until the end of the next Association year, and then only by the payment of the back dues. This step was taken to ensure continuity, and to prevent employees from withdrawing when well and reentering when faced with impending illness or operations. The employee himself is subject to medical examination on application for employment, and if accepted is subject to further examination by a specialist in chest diseases under the Workmen&apos;s Compensation Board of Ontario. Thus it is possible to exclude those who have heart disease, tuberculosis, or other disabling conditions when first employed. Wives and families of employees are not subject to medical examination but other dependents of an employee—mother, father, or other relative—who are declared by the employee to be wholly dependent upon him must be examined. The employee

Jan 1, 1946

As a representative of the Institute in the Joseph A. Holmes Safety Association, which comprises some twenty-three different National Societies, it is proper that I make some report of the progress of the Association to the Institute. The societies represented in the organization are as follows: Association- Representatives, 1916 American Association for the Advancement of Science L. 0. Howard American Chemical Society Charles Baskerville American Electro-Chemical Society F. G. Cottrell American Federation of Labor : A. E. Helder American Forestry Association P. S. Ridsdale American Institute of Electrical Engineers John H. Finney American Institute of Mining Engineers Hennen Jennings American Mining Congress David T. Day American Red Cross Society Maj. Robert U. Patterson American Society for Testing Materials A. W. Gibbs American Society of Mechanical Engineers..... John A. Brashear

Jan 4, 1917