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By D. W. Frommer, M. M. Fine

Early in 1957 St. Joseph Lead Co. announced discovery of three new centers of iron ore deposition in east central Missouri.1 The discovery resulted from exploratory drilling in the vicinity of a magnetic anomaly or high. A deep hole, drilled into the Pre-Cambrian porphyry to determine the cause of anomaly, penetrated a magnetite-rich deposit.2 The magnetic surveys that revealed the anomalies were begun by the Missouri Geological Survey in 1929 and were continued into the 1930's 3. At that time an area in Crawford County known as the Bourbon magnetic high was located. A second anomaly, similar in size and intensity, was discovered about six miles to the northeast in Franklin County in the vicinity of Sullivan. This area was not studied in detail until the early 1940's.

Jan 3, 1959

CONTENTS PAGE East Texas, except the Gulf Coast-H. Vance 3 Gulf Coast-L. P. Teas 8 Texas Panhandle-C. C. Rae 16 North Central Texas-H. F. Smiley 23 North Louisiana, South Arkansas and Mississippi-B. C. Craft 25 Oklahoma-C. H. Pishny, Raymond M. Carr and E. J. Dickinson 31 Kansas-E. A. Koester 35 Rocky Mountain District-C. D. Johnson 46 Illinois and Indiana-T. Wasson 49 Michigan-T. Wasson 52 Eastern States-P. D. Torrey and W. H. Young, Jr 58 West Texas and New Mexico-W. V. Vietti. Published as a Supplement.

Jan 1, 1933

INTRODUCTION TO COMPOSITING Individual drill hole samples may vary greatly in size, length, and weight. The sample interval may represent any convenient unit of hole length, and is usually related to the type of drill being used to obtain the sample. Depending upon the type of mineral deposit, it is desirable to group the individual sample values into composite weighted values representative of some particular zone or volume of the ore body. For example, values of several sequential samples of diamond drill core 3 m (10 ft) in length may be grouped together to represent a 12-m (40-ft) sample value over one bench height. On the other hand, several individual sample values taken across the thickness of a stratiform deposit or a vein zone may be weighted together to represent the value of the total thickness at the point of intersection. The choice of composite intervals is usually dictated by the type of mineral deposit and the mining method selected to produce the mineral. The techniques of weighting values from various lengths of samples into a composite value has already been discussed briefly in Chapter 3. Further examples of determining weighted composite values will be given in the following discussion on compositing for various types of mineral deposits. SAMPLE VALUE COMPOSITES AND TYPES OF MINERAL DEPOSITS There are many kinds of mineral deposits, each of which will require special treatment of sample data to obtain the best composite intervals for evaluating the deposit. It cannot always be known before hand what the optimum composite interval will be. Such composite intervals may properly be determined by geologic factors that are often unknown prior [ ]

Jan 1, 1980

By D. A. Thomas, E. S. Meieran

Tungsten wires were examined by transmission electron microscopy after drawing and after high-temperature annealing. Drawn wire consists of highly elongated grains called fibers, whose long axis is parallel to [110]. Each fiber is ribbon-shaped, with the wide dimension of the ribbon parallel to (001) and the narrow dimension parallel to (110). Furthermore, most fibers are bent about [I10] and twisted along their length. The fibers are divided into cells, which in some cases contain a platelet substructure lying on (110) planes. The misorien-tations of these platelets accumulate to allow the macroscopic twist of the fibers. During annealing, several competing reactions occur, starting at different temperatures and progressing at different rates. Among these processes are fiber-boz~ndary migration, polygonization, dislocation rearrangement, and possibly impurity segregation. The fiber-boundary migration accompanied by the formation of transverse boundaries during polygonization leads to an equiaxed grain structure although recrystal-lization does not occur. There is a relationship between the flow stress of the wires and their average subgrain width in the form sy = s0 + kyd-1/2 . Also, there appears to be a relatio'nship between wire ductility and the formation of transverse boundaries during annealing at about 800°C. THERE have been many investigations of the structures and properties of tungsten wires1-4 due to their commercial importance for use as lamp filaments. The structural studies have so far been limited to optical microscope and replica electron-microscope studies. due to the difficulty of .-me- paring from wires thin foils which can be examined by transmission electron microscopy. However, this difficulty has been recently overcome,5 and it is now possible to examine tungsten wires by transmission electron microscopy as well as by other techniques. In this paper, the structure of drawn tungsten wire is described, as are the changes in the structure during high-temperature annealing. Some discussion of the relationship between structures and properties is also given. EXPERIMENTAL MATERIALS AND PROCEDURES Commercial 0.030-in.-diam doped tungsten wires drawn at progressively decreasing temperatures between about 1400° and about 800°C were examined. The composition, mechanical properties, and optical microstructures are described in detail elsewhere.' All experimental materials were vacuum-annealed for 10 ot 30 min at temperatures at 100°C intervals between 700° and 2000°C. Specimens were thinned for examination in the Siemens Elmiskop I electron microscope by the method of Meieran and Thomas.5 STRUCTURE OF AS-DRAWN WIRE The optical microstructure of as-drawn tungsten wire has been described by Peck and Thomas.7 They observed that wire in longitudinal section consists of highly elongated grains called fibers whose width varies between 1 and 10 µ, while in transverse section the fibers appear to be elliptical in cross section and bent about their common [110] wire axis. They explained this unusual appearance as being due to the drawing of a bcc material with a [110] texture, and predicted that the wide and narrow planes of the fiber cross section would be parallel to (001) and (110), respectively. The fibers apparently bend about the [110] axis during drawing to maintain grain boundary continuity during drawing. Transmission electron microscopy offers a way of checking these predictions as well as providing a more detailed picture of the wire structure. Figs. 1, 2, and 3 are typical electron micrographs of

Jan 1, 1965

By F. Clerf

BLAST-FURNACE practice in France is determined more or less by the character of the ores used. Some French ores are siliceous and others are calcareous, therefore by proper burdening a self-fluxing mix can be used. This is not always clone, as, for instance, at the Caen furnaces of the Société Métallurgique de Normandie, where the Soumont ore of Normandy is used, which is a carbonate. This ore is crushed and calcined at the mines, yielding a product that is porous and well sized for blast-furnace consumption. The lines of the Caen furnaces are given in Fig. 1. Originally these furnaces had 16 tuyeres; six are plucked and these tuyeres are set in the lower part of the bosh. Operating data on these furnaces are given in Table 1.

Jan 1, 1937

By A. T. Beckwith

This paper concerns measurements of low-velocity air currents and investigations on mine ventilation by means of chemical smoke. The chemical smoke used is produced without flame and at ordinary mine temperatures, and therefore presents no ignition hazard in gaseous mines. Mining men who have worked in open-light mines are familiar with the use of tobacco smoke in determining the direction of air travel and approximately measuring low-velocity air currents. The use of chemical smoke is merely a refinement on the use of tobacco smoke and the flameless low-temperature source of chemical smoke has the additional advantage that it can be used in gaseous mines. Ventilation smoke apparatus, Fig I, is a simple device for producing dense white smoke. The apparatus as shown consists of a rubber aspirator bulb which is used to force air through a glass "smoke tube" containing a chemical substance that produces a dense white smoke on contact with air. The apparatus was developed by engineers of the U. S. Bureau of Mines.' It is inexpensive, weighs less than 3 oz, is easily carried in a pocket, and requires no skill to operate. Smoke apparatus is invaluable in practical mine ventilation work for: (I) measuring low-velocity air currents, (2) detecting air leakage, (3) observing airflow characteristics. This paper is written to show the merits of the apparatus, and is based upon findings through its extensive use, during the past six years, in mines operated by the Lehigh Navigation Coal Co. Inc. The Apparatus Certain chemicals, such as stannic chloride (SnCl4) and pyrosulphuric acid (H2S2O7) produce "white smoke" when exposed to air. Stannic chloride gives off vapors which on contact with moist air cause the formation of solid hydrates, of which SnCl4.5H20 is the most important. Pyrosulphuric acid decomposes when exposed to air with the evolution of sulphur trioxide (SO3) fumes, which become white upon contacting moisture in the air. A chemical, such as one of the above, is the active substance in a smoke tube. The glass tubes are hermetically sealed during manufacture, and are made ready for use by merely breaking off the tips at the conveniently located file cuts. When the smoke tube is connected to the aspirator, depressing the aspirator bulb forces air into contact with the chemical, and smoke discharges from the open end of the tube. A white solid (a hydrate if stannic chloride is used, or sulphur trioxide if pyrosulphuric acid is used) may occasionally form a cake in the outlet opening of a smoke tube. A small wire such as an ordinary paper clip can be conveniently employed to dislodge the cake should it seal the tube. When the assembled apparatus is not

Jan 1, 1949

By Walter R. Crane

PAGE I. Apparatus and Methods.......... 406 1. The Magnetic Circuit...........406 2. Apparatus Employed in the Traction-Method...... 406 a. The Coils............409 b. The Pole-Pieces..........409 3. Methods of Testing Fields Produced by Different Pole.Pices.. ..409 c. Testing with a Search.Coil........410 d. Testing with Iron-Filings and Glass Tube.. .. .410 4. General Forma of Pole-Pieces.........411 e. Flat Poles............411 f. Conical Poles........... 411 g. Spherical Poles...........411 h. Chisel-Edged (Chamfered) Poles.......412 II. Magnetic Fields...........412 5. Methods of Testinq for Magnetic Permeability...... 421 i. The Rod-Method..........423 j. Method Employed in These Experiments......424 k. Difference in the Results of the Two Methods..... 425 l. The Traction-Method.........427 m. Effect of Loosening the Charge.......430 n Corrections...........432 6. Theory.............433 o. Effect of Varying Weight on Tractive Force..... 434 p. Effect of Varying Pole-Distance.......436 q. Effect of Varying Magnetization.......436 T. Effect of Varying Size.. .......437 a. Summary,........... 441 III. The Relative Magnetic Permeability of Various Minerals,. 443 The form and strength of magnetic fields have attracted much attention. especially in connection with the designing of dynamo-electric machinery—an art which has been revolution-

Jan 1, 1902

By Norman C. Britz, Mortimer P. Buck

THIS PAPER DEALS WITH the practices used at the Huntington, Nest Virginia works of The International Nickel Company, Inc., in hot and cold rolling nickel and high-nickel alloys. The practical metallurgical aspects are discussed and a brief description of equipment given. The alloys covered may he divided into three main groups. based on their major constituents: 1. Nickel alloys, 2. Nickel-copper alloys. 3. Nickel-chromium alloys. The nominal compositions of the various alloys which are produced in most common mill forms are given in Table 1. Nickel, a commercially pure grade of nickel containing about 0.05 pct carbon as' the chief alloying element, is produced in all common Mill forms. "L" Nickel is commercially pure nickel in which the carbon content is held as low as possible, usually less than 0.01 pct. This grade of nickel is used chiefly for spinning and for special high temperature applications where its low carbon content enhances its corrosion resistance. "D" Nickel contains 4.5 pct manganese to provide improved resistance to sulphur embrittlement at elevated temperatures. "Z" Nickel is an age hardening grade of nickel containing carbon, aluminum, and silicon as the age hardening elements. This alloy combines the cor-

Jan 1, 1948

By W. E. Bruce, R. J. Morrell, James Paone

This chapter is a partial summary of an investigation by the U.S. Bureau of Mines (USBM) made in response to a recent request by the Assistant Secretary, Water and Power Development of the U.S. Department of the Interior, for a comprehensive review of horizontal boring technology related to underground power-line installation. This review is concerned primarily with 3 to 36-in. diam horizontal holes from several hundred to several thousand feet in length. An electric power system consists of three essential functions: generation, transmission, and distribution. The generation component includes the generating station and step-up substation; the transmission component includes the transmission line and stepdown substation at typical voltage levels ranging from 69 to 345 kv for underground lines and 69 to 500 kv for overhead transmission lines; the distribution component includes the distribution line carrying the commonly used voltages of 120, 208, and 240 v, the distribution transformer, and the line to the service customer.l The Federal Power Commission reports that 1600 miles of underground transmission lines of 60 to 345-kv capacity are now in service in the United States. By 1980, it is estimated that approximately 3000 miles of trans- mission lines will have to be placed underground.2 The cost of burying electric transmission lines underground in metropolitan areas, approximately 30 miles from the center of each of the most populated cities, will exceed $1.5 billion with the methods now available. The wide spread in unit costs of overhead and underground transmission lines narrows as right-of-way costs for overhead transmission in congested areas increase. Improved methods of underground emplacement will certainly reduce this difference in costs and even further favor underground emplacement. Also, in the future, overhead transmission lines will probably not be permitted in highly built-up areas.

Jan 1, 1970

By W. C. Winegard, C. Feng, C. Elbaum

SEVERAL investigations have been made concerning the effect of oxygen on the mechanical properties of titanium 1-6= In particular, the yield strength has received considerable attention. Finlay and snyder2 report a 0.2 pet strain offset yield strength if 49 kg per sq mm in titanium containing 0.1 pct 0 and 61 kg per sq mm in titanium with 0.2 Pct 0. These results are in good agreement with those of Jaffee, Odgen, and Maykuth3 who report values of yield strength

Jan 1, 1960

By S. J. Rothman, J. J. Hines, D. Rokop, R. Bastar

Self-diffusion has been measured along each principal axis of mosaic-structured and relatively perfect a uvaniuln single crystals. The anisotropy reported before,' D[loo] = D[001] » D[010 , has been confirmed. and is shown to represent volume diffusion. Diffusion along the dislocations in the imperfect crystals increases the measured value of D significantly without changingr either the shapes of the penetvation plots or the anisotropy. SINCE a uranium is orthorhombic, the diffusion coefficients along the principal crystallographic axes need not be equal. A previous measurement of self-diffusion in three mosaic-structured a uranium single crystals1 showed that Dil00| =D[001 >>D[010 This result was deduced from penetration plots similar to those in Fig. 1. That is, the plots for diffusion along [loo] and [001] were the straight lines expected from the solution of the diffusion equation for the boundary and initial conditions of the experiment, while the plot for diffusion along [010] was curved so that the part near X = 0 had a much steeper slope than the straight lines did. The observed anisotropy could have been due either to volume diffusion or to diffusion along the very large number of dislocations in such crystals, according to the model proposed by aart.' The authors of Ref. 1 argued that the latter possibility was unlikely, but did not exclude it. To settle the question, a simultaneous measurement of self-diffusion in mosaic-structured and mosaic-free crystals was carried out. This paper reports the results, as well as a measurement of the temperature dependence of self-diffusion in a uranium. EXPERIMENTAL The single crystals of a uranium used in this experiment are listed in Table I, together with other experimental details. '(Mosaic structured" here means crystals grown by solid-state phase change.3 The Laue spots from such crystals spread over about 6 deg of arc, which indicates that the density of dislocations is very large. "Perfect" crystals are ones grown by Fisher's grain-coarsening tehnique; the Laue spots from these are quite sharp,4 which shows that the dislocation density in these crystals is much lower. All of the crystals were made from high-purity uranium; a typical analysis is given in Ref. 1. The actual diffusion directions were within a few degrees of the nominal. The thin layer-sectioning method was used. The experimental techniques were similar to those described in Ref. 1, except the sectioning. Crystals Za, 2b, 2c, 4a, 4b, and 4c were sectioned on a lathe. Crystals 3a, 3b, and 3c were sectioned by grinding on glass plates, with 1 p diamond powder in butyl alcohol as the abrasive. The use of glass plates eliminated the crowning noted in Ref. 1, and the use of butyl alcohol as a lubricant simplified the chemical processing of the sections. Material from the sides of these three crystals was removed by spark machining before sectioning. The sectioning of crystals 4a and 4c was botched. A small cylinder of metal was extruded from the center of crystal 4a while turning off material from the side of the sample. Crystal 4c was misaligned by 2.1 x 10"3 cm because the dial gage jammed during the alignment. Notwithstanding these errors, useful data were still obtained from these crystals. The points

Jan 1, 1967

By Matti J. Saarivirta

Two new precipitation hardening copper-base alloys, Cu-1.5pct Ti-2.5 pct Sn and Cu-1.5 pct Ti-2.5 pct Sn-0.4 pct Cr were developed. High strength and medium conductivity are obtained by solution annealing and subsequent heat treatment. Combination of solution annealing, cold working, and heat treatment increases the strength further. Good elevated temperature strength and ductility makes these alloys superior to copper-beryllium-cobalt alloys. A considerable amount of research work is being done throughout the world to develop new and improved copper-base alloys. In many cases, the object is to develop alloys having a combination of high electrical and thermal conductivities, and high strength. The problem is complicated by the fact that any alloying element added to increase strength, invariably decreases conductivity. Among the few commercial precipitation hardening type copper-base alloys, the Cu-Be-Co alloys are best known. These alloys are used in many applications that require good spring characteristics cornbined with high strength and moderately high electrical conductivity. They can be formed readily after solution annealing, then heat treated to obtain high strength and conductivity. Because of the relatively high cost of the Cu-Be-Co alloys, considerable research has been aimed at developing new lower cost alloys having similar properties. As far as is known today, the binary Cu-Ti alloy is the only one whose properties are

Jan 1, 1962

By R. A. Walker, R. G. Bradburn, B. C. Flintoff

The events which led to computer control of the grinding circuit at Brenda Mines are described, beginning with mill operating philosophy. High production rates are encouraged so that, despite severe upstream disturbances, a manual control method to meet this philosophy had developed. Unfortunately, due to the time interval between manual control adjustments, losses in production resulted. An analog control method was devised and, although superior to manual control in some situations, was found to suffer from several practical limitations. The data logging capabilities of a control computer seemed warranted. Circuit testwork combined with an analysis of operating data showed that (1) metallurgical personnel at times could increase production rates by as much as 10% over that achieved by grinding operators; (2) the chosen data base required an increase of 2% or more to be statistically significant; and (3) for a 2% increase there would be a significant rate of return of investment in computer installation. Consequently one grinding circuit was fully instrumented, and a rented computer was installed by Brenda personnel. Prior to installation, Brenda metallurgical and instrumentation personnel were trained in the use of the computer. An experimental program was devised with short and long-term objectives. The short-term objective was to develop a practical control strategy which would yield immediate production improvement. This goal has been successfully met as described in this paper. Statistically significant increases in excess of 2% have been established. Work is being completed for the permanent installation of computer control on all four grinding circuits at the present time. Long-term objectives are (1) off-line analysis of the circuit using mathematical models of process units; (2) on-line experiments to study alternative control tactics; and (3) possible expansion of computer facilities to the crushing plant.

Jan 1, 1978

By E. L. Jr. Spain

THE deposits described in this paper occur over much of Wayne County and in the southeast portion of Hardin County, Tennessee, and in the northeast and northwest portions of. Mississippi and Alabama respec-tively. The presence of tripoli in this region has been known for some time and descriptions of various occurrences in Tennessee have been made by Jewell1 and Miser2, while Hilgard3, Lowe4 and Logan5 have treated the deposits that occur in the adjacent portions of Alabama and Mississippi, but there has not been a general survey of the entire field summarizing completely the geology of the deposits with respect to their origin and stratigraphic relationships. During 1934, while engaged in surveys of mineral resources through this region for the Tennessee Valley Authority, the writer collected data with this in mind, and has assembled them in this report. He is indebted to H. S. Rankin and N. A. Rose, of the Tennessee Valley Authority Geology Division, for field assistance.

Jan 1, 1936

By H. B. Probst

Mechanical twins were produced in zone-refined tungsten single crystals by explosive working at room temperature. These twins are parallel to (112) planes and have irregular boundaries rather than the classical plane twin boundaries. These boundaries aye grooved surfaces in which the grooves themselves are parallel to a <111> direction and the sides of the grooves appear to be par-allel to (110) planes. TWINS were produced in tungsten single crystals by explosive working at room temperature. These twins differ in character from any previously reported for tungsten; however, they are similar to those found in molybdenum after compression at -196°C.1 Deformation twins "resembling Neumann bands in ingot iron" have been observed in tungsten by Bech-told and Shewmon.2 This observation was made with sintered polycrystalline tungsten pulled in tension to fracture at 100°C and using a strain rate of 2.8 x 10-4 sec-1. More recently Schadler3 found deformation twins in zone-refined tungsten single crystals pulled in tension at -196"&apos; and -253°C. These tests were conducted using a strain rate of 3.3 x l0-4 sec-1, and the twin bands were found to be parallel to a (112) plane. Deformation twins in tungsten&apos;s sister metal, molybdenum, were observed by Cahn.4 These twins were produced by compressing small (0.7 mm) vapor-deproducedposited molybdenum single crystals at -183°C. The compression was performed &apos;by impact." By the use of precession X-ray techniques, Cahn was able to identify the twin plane as {112} and the shear direction as <1ll>. Mueller and Parker1 produced deformation twins in polycrystalline electron-beam-melted molybdenum by compression at -196°C. Their "loading rate" was 5000 psi per min which, judging from their stress-strain curve, corresponds to a strain rate of approximately 0.3 x 10-4 sec-1. These twin bands were found to be parallel to (1 12) planes; however, they differed in appearance from previously observed twins. In place of straight and parallel twin boundaries they were found to be irregular, jagged, and sawtoothed. The sides of the saw teeth were identified as (110) planes and irrational planes of a (111) zone. The twins observed in the present work in tungsten single crystals are similar in appearance to those of Mueller and Parker in polycrystalline molybdenum. The starting material used in this investigation was 3/16-in. diam commercial tungsten rod produced by powder-metallurgy techniques. This material was converted to a single crystal by the electron-bombardment floating-zone technique.= The process was carried out in a vacuum of 10-5 mm of Hg using a traversing speed of 4 mm per min. Segments (=2 in. long and 3/16 in. in diam) of two crystals (A and B) produced in this manner were studied. Crystal A received one zoning pass, while crystal B received two passes. The two crystals were explosively worked at Bat-telle Memorial Institute in the following manner. A 1/2-in.-thick layer of plastic was applied to the crystals to serve as a buffer in an attempt to prevent cracking. The composite, crystal and buffer, was then wrapped with 1/8-in.-thick DuPont sheet explosive EL506A2 and detonated in water at room temperature. Metallographic samples of the worked crystals were prepared, and back-reflection Laue X-ray patterns were obtained using unfiltered molybdenum radiation. RESULTS AND DISCUSSION Blasting the crystals as described above failed to prevent cracking. The crystals fractured into several fragments about 3/16 to 1/2 in. long; however, the fragments were of sufficient size to be useful for the subsequent study. The diamond pyramid hardness of the crystals after blasting was in the range 430 to 450 as compared with 340 for the as-melted material, which shows a definite hardening resulting from plastic deformation. These hardness values were obtained using a 1000-g load and taking readings only in sound portions of the crystals free of cracks. The crystals exhibited profuse twinning as shown in Fig. 1. No such structure is present in the as-melted condition. Most of these twins have jagged twin boundaries and are similar in appearance to those found in molybdenum by Mueller and Parker. The twins in both crystals were found to be parallel to {112} planes. This identification was made by using the conventional two-trace method. Subsequent efforts to describe these twins more fully were carried out on crystal A. If the longitudinal axis of crystal A is placed in the (001)-(011)-(Il l) basic triangle of the standard cubic stereographic projection, as in Fig. 2, then the two sets of twins shown in Fig. 1 are parallel to the (112) and (121) planes. Fig. 3 shows a schematic representation of a twin with jagged boundaries. This type of twin with a <111>

Jan 1, 1962

By Philip M. Mc Kenna

When a new material becomes available to industry, it is useful to describe its properties as a guide to its most effective application; and when the new material may be produced in compositions having a series of graded properties, tests to select the combination of properties best adapted for various uses are helpful. The class of materials to be considered in this paper are hard tool materials produced by processes of powder metallurgy from hard carbide constituents and various matrices of iron, nickel or cobalt, or alloys of them with tungsten, or tungsten and carbon. The customary use of carbide hard alloys is for metal-cutting tools; although wire-drawing dies, lathe centers, follow rests, grinding rests, burnishers, rolls, extrusion dies, measuring gauges and micrometers, and a number of other tools are also made with these hard alloys as the essential wear-resisting parts. The properties and tests to be considered are those affecting these uses. In the development of tool materials since the industrial revolution we have had carbon tool steels, Mushet steel, high-speed steels, stellites, and now cemented carbide compositions. For an understanding of the latter category of materials their properties and uses relative to the older and more familiar tool materials will be considered. Hardness has been the property of greatest practical interest in tool materials. The word "hardness" is a generalized term lacking definite-ness unless the specific test used is described. However, efforts to explain physical properties as a consequence of chemical bond, and distance between atoms in chemical compounds have been illuminating. This seems the most generalized attack on the problem, and is based upon the idea that atoms in a lattice are held together as the square of the valence and inversely as the square of the distance between the atoms. The compounds compared must all be of the same crystalline arrangement. 100 W2 It is interesting to note the values of the figure 7 A 3 /3for a number of

Jan 1, 1938

By Philip M. Mc Kenna

When a new material becomes available to industry, it is useful to describe its properties as a guide to its most effective application; and when the new material may be produced in compositions having a series of graded properties, tests to select the combination of properties best adapted for various uses are helpful. The class of materials to be considered in this paper are hard tool materials produced by processes of powder metallurgy from hard carbide constituents and various matrices of iron, nickel or cobalt, or alloys of them with tungsten, or tungsten and carbon. The customary use of carbide hard alloys is for metal-cutting tools; although wire-drawing dies, lathe centers, follow rests, grinding rests, burnishers, rolls, extrusion dies, measuring gauges and micrometers, and a number of other tools are also made with these hard alloys as the essential wear-resisting parts. The properties and tests to be considered are those affecting these uses. In the development of tool materials since the industrial revolution we have had carbon tool steels, Mushet steel, high-speed steels, stellites, and now cemented carbide compositions. For an understanding of the latter category of materials their properties and uses relative to the older and more familiar tool materials will be considered. Hardness has been the property of greatest practical interest in tool materials. The word "hardness" is a generalized term lacking definite-ness unless the specific test used is described. However, efforts to explain physical properties as a consequence of chemical bond, and distance between atoms in chemical compounds have been illuminating. This seems the most generalized attack on the problem, and is based upon the idea that atoms in a lattice are held together as the square of the valence and inversely as the square of the distance between the atoms. The compounds compared must all be of the same crystalline arrangement. 100 W2 It is interesting to note the values of the figure 7 A 3 /3for a number of

Jan 1, 1938

By Charles Barrett

THE experiments reported in this paper have been fruitful in disclosing the mechanism of the deformation of iron in compression. They have established the nature of "deformation bands," "etch bands," or "X-bands," that have been a recognized but little understood feature in the structure of cold-worked metals since the early days of metal-lography, and have shown the role of the bands in the development of preferred orientations by cold-working. The work has also shown the relation of the orientation of individual grains to the preferred orientation of the aggregate. Some of the methods previously used in the determination of the indices of slip planes and slip directions are shown to be untrustworthy in the presence of deformation bands. The conclusion is reached that many slip planes and slip directions must operate during each stage in the compression of a single crystal, and that theories failing to take account of this require revision. In conducting the experiments a method f compression has been used by which extreme reductions can easily be reached, even to the limit set by the metal&apos;s capacity to deform with-out fracture. The work is a portion of a research program on the plastic properties of iron and steel. It is being used as a foundation for studies of orienta-tions resulting from recrystallization and is being extended to other metals and other types of deformation.

Jan 1, 1938

By G. Sachs, E. J. Ripling, J. J. Lynch

It is general practice to evaluate the strength properties of a particular metal from its stress-strain (s1 — el) curve obtained by means of a conventional tension test. Such a stress-strain curve, Fig I, illustrates two important properties of a metal, its ability to strain harden, and its ability to withstand a certain limiting stress, the "fracture stress," (s), and a certain limiting strain, the "ductility" (es), before it fails by separation. These two fracturing characteristics are the coordinates of the point of fracture in Fig I. In the case of a metal which necks in a tension test, both the fracture stress and the ductility (measured in a tension test) are dependent upon (I) the shape of the neck and (2) average values of the stresses and strains over the cross-section at the moment of fracture. However, for the pur. pose of this investigation, these average quantities, rather than the actual values, may be considered for reasons of simplicity. It appears that the conclusiom also hold true if the analysis were carried out for actual values of fracture stress and ductility at the locos of failure. In this paper, the effects of straining (at room temperature) by various methods on the above metal characteristics, which were determined by subsequent tension tests will be discussed. According to Our present knowledge, any such prestrainitlg results in a stress-strain curve (in subsequent testing by tension), Fig 2, the general shape, or flow characteristics, of which can be derived from the original stress-strain curve of the unstrained metal minus a certain portion exhausted by the initial straining. This phenomenon is called strain hardening, and may be measured by the magnitude of the cut-off, or the "effective strain,&apos;&apos; from which the new curve must start in order to coincide in its plastic branch with the original stress-strain curve.

Jan 1, 1949

By William C. Hagel

Oxygen-18 exchange between gaseous oxygen, held at a pressure of 125 mm Hg in a PL-IORh chamber, and splzeres of a Fe2O3 containing three or less grains was determined from 9000 to 1250°C. Isotope equilibrum on crystal surfaces appears to be quickly established, and the rate-determining factor is self-difiusion confbvrning to the relation D = 2.04 esp(- 77,900/RT) sq cin sec-&apos;. Changing sphere diameters caused no detectable variation in diffusion coefficients. Oxygen ions diffuse faster than cations at low temperatures, but a crossover may occur at about 1150°C. INVESTIGATIONS by Davies et al.&apos; and Himmel et al2 have suggested that the mechanism of iron oxidation above 600°C involves a predominance of cation migration in the wüstite (FeO) and magnetite (Fe301) layers and oxygen-ion migration in the hematite (a Fe2O3) layer. Evidence for little cation migration during hematite growth consists of: 1) the disappearance of radioactive-silver markers, presumed to vaporize from the oxide-gas interface, and 2) a large discrepancy between parabolic rate constants for magnetite oxidation and those calculated from Lindner&apos;s3 data for cation self-diffusion, D:, using Wagner&apos;s theory.4 Reversing the calculations gave anticipated self-diffusion coefficients, D:, for oxygen ions of 3.6 x 10-9 sq cm sec-1 at 1100°C and 5.9 x 10-10 sq cm sec-1 at 1000°C. Since then Kingery et a1.5 reported three values for oxygen-ion diffusion in polycrystalline, sintered hematite. These were obtained near 1200°C, at an oxygen pressure of approximately 150 mm Hg, and could be represented by the Arrhenius expression, Dg = 1 x 10 11 exp(-146,000/RT) sq cm sec-1. Extrapolation to temperatures below 1100°C infers that oxygen ions are less mobile than cations. This contradicts the aforementioned oxidation evidence and also coble7s study of the initial sintering of hematite. From the latter, apparent diffusion coefficients for the slowest rate-controlling species could be calculated, and fair agreement was found with an extension of Lindner&apos;s data for cation diffusion. Fig. 1 depicts such comparisons graphically. Three points have been included for the determinations of Himmel et al. on cation diffusion in large, natural hematite crystals surrounded by pure oxygen at atmospheric pressure. No dependence on crystal log raphic direction was noted. Since the value of 10-l4 sq cm sec-&apos; at 1000°C actually represents an upper limit, one might interpret that there is a small decrease in D: when single crystals are employed. On the whole, however, cation diffusion appears relatively well-defined,* while the few results tension to lower temperatures. After having gained experience measuring oxygen-ion diffusion in certain glasses7 and in the corundum oxide, a Cr2O3, the purpose of this work was to determine D; values for hematite and thus possibly assist a mechanistic understanding of the kinetics of the oxidation and reduction of solid iron oxides. I) EXPERIMENTAL PROCEDURE A) Material. Hematite powder of moderately high purity was received from the Columbian Carbon Co. An accompanying lot analysis listed 0.03 H2O, 0.008 weight percents, with the remainder Fe2O3. Subsequent treatments were ball milling, drying, prepressing, and hot-pressing for 60 min at 1350°C under 5000 psi. Since graphite dies coated with a slurry of alumina were used for hot-pressing, the surrounding atmosphere at temperature was sufficiently reducing to form some magnetite on the outer surface of each cylinder. After removing any attached alumina, a stabilizing anneal of 50 hr at 1300°C in oxygen was added. The final product was nonmagnetic and exceeded 97 pct of the density (5.24 g cm-3) usually given for FezO3. On polishing cylindrical ends, counts were made of the number of grain boundary intercepts per

Jan 1, 1967