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By Nirander M. Safaya

Revegetation success on surface mined lands is dependent upon the nature of the plant growth media. Soil physical and chemical properties dictate the needs for specific reclamation and subsequent management practices. Field experiments were conducted at six coal mine sites in Oliver and Mercer Counties, North Dakota to determine the subsequent effects of a single application of selected amendments on spoil and topsoils over the five year period, 1974-1978. Considerable variations in the physical and chemical properties were found in mine spoils from site to site. The texture of spoils ranged from sandy clay loamy at North Beulah I to loamy at Glenharold, and from sandy loamy at North Beulah 3 and South Beulah sites to loamy sands at the Center site. The pH of the sites ranged from 6.5 at South Beulah to 8.2 at North Beulah 3. In many cases, the pH values of mine spoils were not significantly different from the topsoils. The electrical conductivity (ECe) did not exceed 6 mmhos cm-1 at the test sites even though in other studies much higher values were recorded in the same vicinity. The spoils from Glenharold and North Beulah test sites can be classed as moderately saline, and those from Center and South Beulah as non-saline. The sodium adsorption ratios (SAR) varied from less than 1 to 32, with highest values in the spoils of North Beulah 3 followed by Glenharold; all other sites were nonsodic. Lowest SAR values (less than 1) were found in the topsoiled sites at South Beulah and Center. Spoils of North Beulah 3 test site were highly calcareous, followed by North Beulah 2 and Glenharold. Center mine spoils which were the least calcareous of the test sites, showed the calcium carbonate equivalent three times higher than that of the topsoil. The average calcium concentrations in the spoils of North Beulah 3 and South Beulah test sites were -13 and 14 me 100g -l while at North Beulah 2 and Glenharold test sites 25 and 22 me 100-1-1 were recorded, respectively. The overall magnesium concentrations ranged from an average of 4 to 16 me 100g 1. Sodium concentrations in all sites never exceeded 10 me 100g-1. Phosphorus concentrations on the average at North Beulah 1, North Beulah 2, and Center were 10.2, 4.6, and 22.2 µg g -1 spoil, respectively. Concentrations of potassium ranged from 200 ppm at South Beulah site to more than 375 pp in at the Glenharold site. High concentrations of sulfates (239-2778 µg g-1) seem to contribute to the salinity in these spoils. Chloride concentrations of spoils were low and never exceeded 40 µg g-1 spoil. Based on established critical levels of deficiency for micronutrients in agricultural soils, it seems that none of these were deficient. However, controlled environment experiments did reveal increased plant growth responses when some micronutrients were added to the mine spoils. Treatment effects were highly site specific depending on the nature of the soil/spoil characteristics and, of course, the properties of the various treatments. While slack coal amendment to the spoils at North Beulah 2 site affected significant increases in a large number of variables (both major and trace elements), amendment of the topsoils at the South Beulah test site with leonardite resulted in significant decreases in a number of variables, particularly trace elements. Spoils at Glenharold and North Beulah 3 demonstrated the fewest significant changes due to amendments. Calcium, magnesium, strontium, organic matter and nitrogen were consistently increased from site to site with the addition of lignitic materials. Other spoil/topsoil physical and chemical properties (30 variables) as affected by amendments and time are discussed.

Jan 1, 1982

By T. Sterry Hunt

Jan 1, 1882

By R. R. Nash, W. F. Sheely

Experiments were conducted on magnesium monocrystals in order to collect quantitative information on the mechanisms which limit the rate of basal slip. Using critical shear stress and creep data, activation energies for creep at low aid at high temperatures were derived. The activation energy at low temperatures is the same as that for jog formation and the activation energy at high temperatures agrees with that for climb. COTTRELL has suggested that at low temperatures, the expansion of dislocation loops under stresses near the yield strength is limited by the rate at____ which the expanding loops can cut the "forest" of dislocations passing through the glide planes.' On the basis of this mechanism, seeger2 has derived expressions for low-temperature creep and for the relation of flow stress of single crystals to temperature. In the work reported here, the authors have performed experiments designed to obtain quantitative data on the physical properties of the dislocation intersection mechanisms operating during basal slip in pure magnesium monocrystals. Above a critical temperature, dislocations thread-

Jan 1, 1961

By Leizhang Gao, Zhengfeng Qu, Pingsheng Lai, Chenguang Bai, Meilong Hu

FFC process could be used to prepare titanium foams. The mixed oxides CaO-TiO2 with mole ratio 1:2 were sintered into CaTiO3-TiO2 mixture. CaTiO3-TiO2 was then used as cathode and electrolyzed in molten CaCl2 to prepare porous titanium. The porous titanium with the porosity of about 72.15% was first fabricated. The internal pores are in the presence of circular cavities and the pore size is in the range of 50–100 lm. Compared with the powder metallurgy technique using the space-holder this method promises to be lower cost and less processing. It is potential to fabricate titanium foams using FFC process.

Mar 1, 2018

SYMPOSIUM ON THE RECOVERY OF PYRITE The proceedings of the Symposium on the Recovery of Pyrite, held in Johannesburg in June 1969, may be ordered from the Secretary, S.A.I.M.M., P.O. Box 61019, Marshalltown, Transvaal, at the reduced price of R5.00. Papers and addresses presented at the Symposium were: Opening Address by Mr J. K. E. Douglas (President). "The world sulphur position," by W. C. J. van Rensburg (Member). "The South African sulphur position," by D. L. Taylor (Member). "The recovery of pyrite at Government Gold Mining Areas Limited," by R. J. Westwood (Member), G. S. Stander (Affiliate) and H. P. Carlisle (Member). "Recovery of pyrite concentrates from colliery-waste discards-A preliminary assessment," by W. A. Gilbert (Visitor) and E. A. Nugent (Member). "The role of pyrite in upgrading the uranium content of Witwatersrand conglomerate ores by means of the heavy-medium separation process," by D. J. Tutt (Associate Member). "Pyrite recovery by jigs at Durban Roodepoort Deep Limited," by E. J. Dominy (Affiliate), F. Diamond (Affiliate) and A. D. Graham (Affiliate). "The storage of pyrite concentrates," by Joan C. Campkin (Visitor) and P. J. Lloyd (Member). "The flotation plants of the Anglo-Transvaal Group," by L. A. Bushell (Member). "Pyrite flotation with amines and cyanidation of the products," by E. H. D. Carman (Member). "Gold recovery by cyanidation from mill products obtained after pyrite flotation," by P. G. Mrkusic (Graduate), M. Sciarone (Visitor) and H. E. Simonsen (Visitor). "The influence of sulphydryl and cationic flotation reagents on cyanidation of native gold," by K. G. Ashurst (Visitor) and W. P. Finkelstein (Member). "Laboratory tests on the flotation of pyrite from Witwatersrand gold ores by cationic collector," by J. Levin (Member), and M. L. Veitch (Visitor). Closing Address, by Dr R. E. Robinson (Director, National Institute for Metallurgy). INCOME TAX: POST-GRADUATE STUDY COURSE CONCESSION As a result of representations made by the Associated Scientific and Technical Societies of S.A. and the Suid-Afrikaanse Akademie vir Wetenskap en Kuns, engineers and scientists will now be allowed to deduct expenses incurred on post-graduate study courses from their taxable income. The conditions of this concession are set out in section 16 of the Income Tax Act, 1969, which reads as follows: 16. (1) The following section is hereby substituted for section 16 of the principal Act: 16. "Notwithstanding the provisions of section 23(a) and (b), there shall be allowed to be deducted from the income of any person who is a dentist or medical practitioner or practises any profession referred to in paragraph (a), so much as the Secretary may allow of any expenditure incurred by such person in the circumstances contemplated in paragraph (c), if the Dental Association of South Africa in the case of a dentist, or the Medical Association of South Africa in the case of a medical practitioner, or the "Suid-Afrikaanse Akademie vir Wetenskap en Kuns" or the Associated Scientific and Technical Societies of South Africa in any other case, certifies in such form as the Secretary may prescribe that such person- (a) if he is not a dentist or medical practitioner, is the holder of a degree in engineering or allied technology or natural sciences awarded by a recognized university on completion of a prescribed minimum period of study of not less than four academic years or the equivalent thereof and enabling the holder thereof to practise the profession of an engineer or a profession for which advanced and specialised scientific knowledge is required which relates directly to- (i) the development or exploitation of natural resources; (ii) mining or prospecting for minerals; (iii) the production of pastoral, agricultural or forest produce ; (iv) the breeding or care of farm animals; (v) any industrial process; or (vi) the training of specialists in any branch of science or technology connected with any aforementioned profession; (b) has practised his profession for not less than three years; and (c) has incurred such expenditure during the year of assessment in respect of the attendance by him of any postgraduate study course approved by such body to improve his qualifications for carrying on his profession in the Republic". (2) The amendments effected by subsection (1) shall first take effect in respect of assessments for the year of assessment ending on the twenty-eighth day of February, 1970. From this section it is clear that the concession will only be granted if the application is accompanied by a certificate, which certificate must be either signed by the Chairman of Die Akademie or the President of the Associated Societies. In terms of the authority granted such certificates must certify that: (i) the taxpayer concerned has practised his profession for not less than three years; (ii) the expenditure was incurred by the taxpayer during the year of assessment indicated in the certificate; (iii) the expenditure was incurred by the taxpayer in respect of the attendance by him of a post-graduate study course approved by the Associated Scientific and Technical Societies of South Africa or Die Suid-Afrikaanse Akademie vir Wetenskap en Kuns, as the case may be, to improve his qualifications for carrying on his profession in South Africa; (iv) the taxpayer is the holder of a degree in engineering or allied technology or natural sciences, which degree was awarded by a recognized university,

By William (Bill) H. Walton

"I arrived in Chicago in 1993 with Dr. Ralph Peck’s University of Illinois bulletin titled Engineering Properties of Chicago Subsoils (Bulletin 429), which he published in 1954 with William Reed. Being an outsider, I wanted to learn from Chicago geotechnical practice leaders that included Clyde Baker, Jr., John Gnaedinger, Charles Pfingsten, Dr. Safdar Gill, Robert Lukas and Dr. Jorj Osterberg, who have influenced foundation designs for the structures that make up the contemporary Chicago skyline. One of my immediate goals was to get the Illinois Structural Engineering license to be on par with the likes of Eli Cohen, Mike Tylk, Stan Korista, Bob Halverson, Joe Burns, Ron Johnson, Bill Baker, Bob Sinn, Chuck Anderson and Dave Eckmann, who have led their structural firms in the design of the skeletal core and frames of many of Chicago’s iconic buildings (and for many other buildings around the world). From my time with GEI Consultants (GEI), then on with STS Consultants (STS, and now AECOM), and now back with GEI, I have had the opportunity to analyze and design foundations and, with the help of many skilled foundations and building constructors, to verify that predicted foundation performance matches actual movement data. The theme of Chicago’s foundation design practice is to assume and verify. In 1948, Peck published the History of Building Foundations in Chicago (Bulletin 373) that was updated in 1998 by Baker, Pfingsten and Gnaedinger, who meticulously documented hundreds of Chicago’s foundations, and have shown the value of advanced analyses and testing to advance the deep foundation design practice that includes a variety of high-capacity driven and drilled deep foundations. Mehmet Uyanik, Peck and Baker have made Chicago’s subsurface into a full-scale foundation test laboratory. They confirmed soil mechanics principles like Terzaghi’s 1-D consolidation theory when early foundations bearing on sand-clay crust over soft to medium silty clays (e.g., Auditorium, Masonic Temple, Monadnock Block and Old Board of Trade buildings) took 40 to 60 years to consolidate clay 1 to 2 ft (0.3 to 0.6 m). They also confirmed proven increases in bearing pressures based on measured performance of deep foundations bearing on the glacially derived hardpan clay till and in solid dolomite that underlies Chicago."

Jan 1, 2017

By S. Jagdish

India ranks fourth in the world of iron ore production and exported 55% of the total iron ore production of 180.9 million tons in 2006-07. As per United Nations Framework Classification (UNFC), the total iron ore reserves in India is 25249 mt. This consists of about 14630 mt of Hematite ore and 10619 mt of Magnetite ore. While the deposits of magnetite iron ore are limited to the states of Karnataka, Andhra Pradesh and Tamil Nadu, hematite ore is available in abundance in Jharkhand, Orissa, Chhattisgarh, Karnataka and Goa. National Steel Policy, declared by government of India in 2005 envisages 110 million tons of steel production by 2020. This is likely to be revised upwards. Massive exploration work in iron ore is needed to convert the available resources of iron ore into reserve category. Steel Authority of India Limited (SAIL) produced more than 24.5 million tons of iron ore during 2006-07 and plans to produce 42.0 million tons per year by the year 2010-11 to meet the requirement for a hot metal production of 26.2 million tons. While processing iron ore, the challenge faced would be the reduction of the gangue materials ? alumina and silica. It is proposed to bring down alumina and silica in the iron ore to less than 2% each from the current level of 2.5%~3.5% each. Appropriate beneficiation schemes are being developed depending upon the mineralogical characteristics of iron ores at different mines in the country. The state-of-art beneficiation technologies like Hydro-cyclone, jigging, magnetic separation etc. will be incorporated. SAIL?s corporate plan envisages blast furnace burden of 15% iron ore lumps, 15% pellets and 70% sinter by 2010. This strategy opens up the opportunity of utilization of micro fines generated in the mining and beneficiation processes for pellet making. This also directs towards all together new technological approach to the beneficiation process. SAIL is planning to set-up three pelletisation plants of 2~3 mtpa capacity. Environmental issues like reduction in slime loss and utilization of dumped low-grade iron ore are very important. R&D Centre for Iron and Steel, SAIL has carried out extensive laboratory investigations in the above area. This will help in reducing the loss of valuable iron through slimes and also increase the iron ore resource base. Laboratory investigations indicate that low grade dumped ore fines with Fe: 55.5% can be upgraded to a product with Fe: 66.2% with about 48% recovery.

Jan 1, 2014

By Thomas Kuhn

The detailed investigation of both active and inactive submarine hydrothermal systems has gained tremendous progress during the last decades because of the increasing usage of remotely operated vehicles (ROV) as well as manned submersibles. Special aspects like the targeted sampling of chimney structures and vent fluids as well as the analysis of zonations of near-surface structures like sulfides mounds was only possible with the usage of such vehicles. However, the availability of such vehicles has been very limited because of the few number of deep-water ROVs and manned submersibles which need both a trained crew and a special research vessel. This was especially true for the German science community which did not have such devices at its disposal until recently. With the ROV QUEST 5 which is based at the University of Bremen (c/o. Prof. Dr. G. Wefer, Dr. V. Ratmeyer) this major drawback has now been eliminated.

Jan 1, 2003

By Anil Mahyera

This report present the results of a laboratory and field research program aimed at design and development of a torque-thrust controlled bolter with the capability to (1) predict the "quality of anchorage" attained while installing mechanical anchor roofbolts, and (2) improve the uniformity and tension levels achieved among a group of roofbolts. The prediction accuracy of the anchorage quality algorithm ranged from low to moderate because of the complexity and variability of the phenomena involved. The best roof support with mechanical anchor bolts was found to be achieved by simply installing them under ? proper torque-thrust control, and with ? a hardened washer under the bolthead. This procedure resulted in an improvement in uniformity of 3 times, along with an increase in mean tension levels of 75% over conventionally installed roofbolts.

Jan 1, 1983

By Guy Demers

"This paper defines the responsibilities and functions of the Maintenance Department, and its organization, physical and human assets, highlighting the unique operating problems. Due to the self-sufficient aspect of the Asbestos Hill Deception Bay project, the Maintenance Department cover-s fields that are numerous and very dissimilar: production, mobile, processing, service, power generation, fire protection, heating, water and sewage disposal equipment. Added to this, buildings, plant and camps, wharves and communications equipment all demand versatility, adaptability and expertise from maintenance personnel. Good maintenance practices are a necessity in this environment and are more critical than at southern locations; that is, high-quality replacement material, complete and well-controlled preventive maintenance, major repairs on a component-replacement basis, updated inventory, efficient training and permanent contacts with suppliers, combined with an equipment improvement program, updated specifications on lubricants, hoses, seals, filters, etc., are mandatory. The seasonal aspect of the operations applies a great deal of pressure on the maintenance team, as the production months do not permit major repairs. Short- and medium range planning and accurate evaluation of equipment conditions highly influence production efficiency. Maintenance control, planning and scheduling do not follow the accepted standard routines, as personnel turnover normally does not permit an accumulation of knowledge of the equipment history and condition by the •individual tradesman."

Jan 1, 1976

By R. N. Johnson

This report is a summary of the work performed for the Bureau of Mines to evaluate the feasibility and desirability of a movable in-pit crusher combined with conveyors to substantially reduce or eliminate truck or train haulage in large open-pit non-fuel mineral mines. The report includes an introduction and summary of previous work, an analysis of movable crusher system components, a description of the selected system, a review of possible movable crusher system applications, and finally requirements for future work to bring about the general availability of such systems. It was clear from the program that there is a real need for movable in-pit crushers.

Jan 1, 1982

By E. L. Rawlins

The development of commercial natural-gas reserves in the Michigan stray sandstone horizon of central Michigan during the past few years has resulted in expansion of the natural-gas industry in that State. The location of the natural-gas reserves of Michigan in the general vicinity of domestic and industrial markets is of economic importance, and in supplying these markets with natural gas a reasonable knowledge of, the extent and availability of the reserves is needed in formulating regulations for drilling gas wells and producing natural gas in analyzing the feasibility of projects to construct natural-gas transmission lines, in promoting and developing markets for the domestic and industrial consumption of natural gas, and in solving many engineering and economic problems common to the natural-gas industry. The development of the natural-gas industry in Michigan has been related closely to the development of oil production. The potential oil production of Michigan is comparable with that in most of the eastern oil-producing States. The development of oil production probably will continue, especially in the central Michigan Basin area; and as wells are drilled to deep horizons in the search for oil, more knowledge will be obtained of the gas reserves in formations above the oil-bearing horizons.

Jan 1, 1936

By F. Sillers, R. T. C. Rasmussen

"INTRODUCTION This is the fourth report of investigations dealing with the cooperative tests between the Bureau of Mines and industry on the use of electrolytic manganese in steelmaking. The first report dealt with the use of electrolytic manganese in the manufacture of stainless steel 3/ the second with its use in acid electric steel practice, 4/ and the third with its use in low-carbon basic open-hearth steelmaking. 2/ A résumé of those investigations E7 appeared in the magazine STEEL. 5/ The present report deals with the use of electrolytic manganese in the manufacture of four types of stainless steel and the new Timken 16-25-6 alloy. The Bureau of Mines supplied The Timken Roller Bearing Co. with 62,000 pounds of electrolytic manganese for use in the tests.The electrolytic manganese was produced at the Bureau of Mines pilot plant, Boulder City, Nev., by the process developed by the Bureau and described in Bulletin 463, Operation of Electrolytic Manganese Pilot Plant, Boulder City, Nev., by J. H. Jacobs. J. W. Hunter, W. H. Yarroll, P. E. Churchward, R. G. Knickerbocker, R. W. Lewis, H.A. Heller, and J. H. Linck. The workcarried out under the direction of R. S. Dean, formerly assistant director, Bureau of Mines, and R. G. Knickerbocker, formerly chief, metallurgical branch, as part of a long-range program involving the development, manufacture, and use of manganese from domestic ores. Preliminary arrangements for the plant tests were made by the late A. A. Dow. 7/"

Jun 1, 1947

By Bobby B. Gillenwater

This report presents recommended guidelines and regulatory changes applicable to electrical installations in underground oil shale mines. These recommendations are based on information gathered from oil shale operators, government agencies, and other knowledgeable sources familiar with existing plans for mining systems and electrical installations, and on present understanding of the problems and hazards associated with oil shale mining. Additional discussions of specific electrical problems related to oil shale mining are also presented. These specific problems include: ? Ground fault current levels ? Permissible electric wheel motors ? Permissible batteries and electric starting systems ? Intrinsically safe instrumentation and applicability of existing test standards.

Jan 1, 1983

By M. M. Hajdasinki

A project's rates of return (RORs)1, be it the internal rates return (IRRs) or one of the many IRR surrogates, frequently needs to be approximated. The success and efficiency an ROR- approximation procedure depend on the quality the approximation-initiating parameters, such as bounds or seed values (guesses). The existing approximation procedures commonly use bounds and guesses suggested by intuition rather than supported by mathematical considerations. This paper presents three mathematically founded ROR-bounding and eleven ROR-guessing approaches and examines their suitability by using examples of typical project cash-flowpatterns (CFPs). The calculated bounds and guesses not only improve the approximation efficiency, but also allow the process of the ROR discovery to be automated, thereby making it more convenient and reliable.

Jan 1, 1999

By B. S. Tani, R. V. Schablaske, M. G. Chasanov

In the Ti-Cd system two intermediate phases, TiCd and Ti Cd, have been found and characterized by X-ray diffraction powder techniques. An earlier reference' had reported the existence of the compound Tisd. No structural details, however, were given nor was there any indication of the possible existence of other binary compounds. Studies of the solubility of titanium in liquid cadmium2 led to the discovery of both TiCd and Tisd. The solid phase in equilibrium with saturated solutions of titanium in liquid cadmium at temperatures below 620°C is TiCd, whereas TizCd is the equilibrium solid phase above 620°C. Both thermal analysis and X-ray studies show that a peritectic reaction between the y phase (~isd) and cadmium to form the 6 phase (Ti Cd) occurs at 620°C. X-ray diffraction powder photographs of material isolated from the ingots used in the solubility measurements as well as material prepared by a direct heat of the appropriate stoichiometric amounts of titanium and cadmium can be indexed on the basis of a tetragonal unit cell with a = 2.904 ± 0.002A, co = 8.954 * 0.004A, c/a = 3.083. No variation of lattice parameters indicative of a range of composition is evident. With four atoms in the unit cell the calculated density of the intermetallic is 7.05 g per cm3; the observed value is 7.07 g per cm3. The TiCd lattice is primitive as indicated by the fact that there are no systematic absences among hkl reflections. The absence of all hko reflections for which h + k = 2n + 1 is also evident. This systematic absence indicates the following two space groups, C\h — P4/n and D&~4/nmm; both groups, however, have the same two- and four-fold positions. Stoichiometry, symmetry and space group indicate two likely structure types. They are the PbO-litharge3 (B10) type and the Ti CU (B11) type. Spatial considerations favor the B11 structure with atoms placed in the following positions: 2Ti (c) 0, 1/2, Z; l/2, 0, Z 2Cd(c) 0, 1/2, Z; 1/2, 0, Z The TiCd structure may be summarily described as a layered structure in which double cadmium layers alternate with double titanium layers along the c-axis. The best agreement between calculated and observed intensities is obtained for the values ZTi = 0.608 and ZCd = 0.130. Calculated and observed powder intensities as well as other pertinent powder data are recorded in Table I. Interatomic distances for the proposed structure are recorded in Table II and are to be compared with the distances of closest approach for titanium and cad-

Jan 1, 1962

By John H. Hollomon

The interpretation of notched-bar impact results has been a matter of controversy since the introduction of more or less standard tests by Fremont,' Charpy2 and others at the turn of the century. Many investigators3-l1 have contributed to the understanding of the significance of such tests. Several symposiums12,13 have been held with the express purpose of discussing the significance and interpretation of the impact tests. It is not the purpose of this paper to review all these contributions to the development of the knowledge on this subject, but rather to present an interpretation of notched-bar impact tests that appears to be in agreement with the available published data. Fundamentally, the interpretation discussed in this paper of the brittle failure of some steels in notched-bar impact test is similar to the qualitative analysis presented by Ludwik3 in the I92o's. Essentially, Ludwik stated that the function of the notch was to increase the tensile stress necessary for yielding, and that brittle failure occurred when the stress necessary for yielding exceeded the normal stress required for fracture (with no plastic deformation). Ludwik, however, had no means of measuring this normal stress necessary for failure of a plastically* undeformed metal, therefore he could not extend his interpretation beyond the qualitative stage. Kuntze14 and recently Mc-Adam15 attempted to determine the effect of deformation on the stress necessary for fracture by testing, in tension, specimens notched to various depths and angles. Because of the uncertainties in Kuntze's (and McAdam's) analysis of the stresses (which have been pointed out by Sachs16) and the inherent nonuniformity in the stress distribution in notched bars, the results of such investigations are difficult to interpret. A more direct method of measuring the effect of deformation on the fracture stress was suggested in previous papers"-18 and has been utilized in the present investigation. The present paper concerns itself primarily with the behavior of notched impact specimens. The effects of strain rate, temperature, and stress distribution, which are discussed with reference to the impact specimen, apply just as well to the behavior of metal at the bases of notches in any engineering structure. All that is necessary is to determine the stress distribution in the structure at the base of the notches.

Jan 1, 1944

By John H. Hollomon

The interpretation of notched-bar impact results has been a matter of controversy since the introduction of more or less standard tests by Fremont,' Charpy2 and others at the turn of the century. Many investigators3-l1 have contributed to the understanding of the significance of such tests. Several symposiums12,13 have been held with the express purpose of discussing the significance and interpretation of the impact tests. It is not the purpose of this paper to review all these contributions to the development of the knowledge on this subject, but rather to present an interpretation of notched-bar impact tests that appears to be in agreement with the available published data. Fundamentally, the interpretation discussed in this paper of the brittle failure of some steels in notched-bar impact test is similar to the qualitative analysis presented by Ludwik3 in the I92o's. Essentially, Ludwik stated that the function of the notch was to increase the tensile stress necessary for yielding, and that brittle failure occurred when the stress necessary for yielding exceeded the normal stress required for fracture (with no plastic deformation). Ludwik, however, had no means of measuring this normal stress necessary for failure of a plastically* undeformed metal, therefore he could not extend his interpretation beyond the qualitative stage. Kuntze14 and recently Mc-Adam15 attempted to determine the effect of deformation on the stress necessary for fracture by testing, in tension, specimens notched to various depths and angles. Because of the uncertainties in Kuntze's (and McAdam's) analysis of the stresses (which have been pointed out by Sachs16) and the inherent nonuniformity in the stress distribution in notched bars, the results of such investigations are difficult to interpret. A more direct method of measuring the effect of deformation on the fracture stress was suggested in previous papers"-18 and has been utilized in the present investigation. The present paper concerns itself primarily with the behavior of notched impact specimens. The effects of strain rate, temperature, and stress distribution, which are discussed with reference to the impact specimen, apply just as well to the behavior of metal at the bases of notches in any engineering structure. All that is necessary is to determine the stress distribution in the structure at the base of the notches.

Jan 1, 1944

By James M. Fragomeni

"The mechanical behavior of an Al-Li alloy was studied and related to the extrusion processing parameters, the plastic metal flow during defonnation, the anisotropy, and the microstructure. The extrusion temperatures, strain rates, extrusion ratios, billet temperatures, and extrusion geometries were varied during processing and correlated with the microstructure and properties. The extrusion processing variables were related to the mechariicar behavior, anisotropy, and microstructure through the ZenerHollomon parameter i.e., the temperature compensated strain rate. Based on optical and electron microscopy studies it was found that regardless of the extrusion conditions, the various microstructures for the most part were unrecrystallized for both the as-extruded and the solution heat-treated conditions. Smaller grain sizes were correlated to larger Zener-Hollomon parameters. The extrusion temperature and ratio did not significantly affect the strength or ductility as did the section geometry, which had a large affect on these mechanical properties. The anisotropy of the properties varied substantially when comparing the extruded longitudinal versus transverse grain orientations.IntroductionThe extrusion process also has a substantial influence on: the microsfructure and mechanical properties of a material that is Athens, Ohio, 45701 fonned The plastic defonnation that occurs during the extrusion process alters the grain size, crystallographic texture, anisotropy, subgrain size, dislocation density and various other microstructural features. Often the material being extruded is not homogeneous, therefore variations in the microstructure and properties occur across the cross-section of the final extruded product. The mechanical properties and microstructure can also vary with length since it is hard to maintain a constant temperature throughout the extrusion process. The extrusion temperature often varies from the heat generated during the extrusion process. The demonstration material that was extruded for this .study was an aluminum alloy containing 2.6wt, % lithium and 0.09wt.% zirconium. This alloy was strengthened by heat treatment causing nucleation, growth, and coarsening of coherent metastable o' (Al3Li) precipitates in the microstructure. The ? precipitates which are a consequence 9f artificially aging the AlLi alloy, are spherical, ordered, and coherent with the aluminum matrix and impede the dislocation glide inotion during plastic defonnation. Theo particles grow homogeneously in the matrix, and have the Cu3Au (L 12)"" superlattice crystal structure. Aluminum-lithium alloys are used primarily for aerospace structural applications since they have attractive properties such as a lower density and higher elastic modulus than conventional 2XXX and 7XXX alloys."

Jan 1, 2000

By C. W. Huggins

The objective of this Bureau of Mines research was to compare the size distribution of respirable quartz collected at coal mines with that of several reference standards used to quantify quartz in coal mine dust samples. Particle size measurements were made on 23 samples and 4 ref-erence standards using a scanning electron microscope in the backscatter electron mode of operation, interfaced with an image analysis system. The Mine Safety and Health Administration provided the 23 respirable coal mine dust samples, which were collected at surface and underground coal mines in 7 States. The accumulated particle size measurements in-dicate three of the reference standards, minus 5-um Min-U-Sil, minus 5-um Supersil, and NBS 1878, would be preferred over the fourth, Silver Bond B, for quantitative quartz determinations in coal mine dusts by X-ray diffraction and infrared spectrometry.

Jan 1, 1985