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By Akihiro Higashide, Roy H. Patten

The DOT Tunneling method combines two conventional earth pressure balance shield machines in an overlapping cylindrical arrangement. The method allows two tunnels to be driven simultaneously with mini¬mum cross sectional area. Two full size trials, one configured horizontally and one vertically stacked, were successfully completed employing the DOT method. The method was then utilized for the new transportation system. The goggle-shaped DOT machine, 9.36 m high by 15.86 m wide, is the largest earth pressure balance shield machine in the world. This paper includes a general description of the DOT tunneling method as well as a history of its development.

Jan 1, 1995

By C. H. Lee, T. T. Wang

"Exampling of the tunneling task in the Tsengwen Reservoir Transbasin Diversion (TRTD) in southern Taiwan, this study investigates the application of the Drilling Survey System (DRISS) in both Drilling and Blasting (D&B)- and Tunnel Boring Machine (TBM)-excavated sections. In the D&B section, a nonlinear relationship exists between drilling energy and uniaxial compressive strength of rock mass, in which a reasonable coefficient of determination can be analyzed statistically. Additionally, the DRISS accurately predicted an unfavorable section with a valuable position. The magnitude of uniaxial compressive strength back calculated using DRISS data also matches those acquired from geological investigations with different approaches. Study results indicate that the DRISS is an effective tool for fore-probing of both D&B- and TBM-excavated tunnels. INTRODUCTIONModern advancements in geological and geophysical investigations, and drilling techniques, have provided valuable information for detecting and interpreting geological conditions of rock tunnels with a resolution of several to ten of meters (Brückl et al., 2001, 2008, Lorang et al., 2005). Nevertheless, construction risks remain considerable during tunnel excavation, especially when a tunnel was excavated by a Tunnel Boring Machine (TBM). Predictions of the local fault, shear zone, and other minor geological features, which may cause moderate collapse or excessive deformation of rocks surrounding the tunnel, before tunnel excavation is highly desirable for high-quality tunnel construction and economically efficient project management.Rather than conventional geophysical prospection methodologies, which always favor large-scale investigation with moderate precision, this study focuses on the drilling method probing ahead of a tunnel. The goal of such an investigation is not only to prevent catastrophic collapse, but also to provide quantitative or semi-quantitative information for estimation of the mechanical parameters of rock mass.For the tunneling task in the Tsengwen Reservoir Transbasin Diversion (TRTD) in southern Taiwan, a drilling survey system is adopted for fore probing. Data collected from both drilling and blasting (D&B) and TBM-excavated sections are analyzed statistically and discussed. The applications of the Drilling Survey System (DRISS) are addressed accordingly."

Jan 1, 2015

By C. A. Rowland

Wet grinding rod mills have been used for 50 years to grind ores and to make specification sand. The application of wet grinding rod mills is well understood. Until recently, there have been very few installations of dry grinding rod mills. The basic principles learned from wet grinding rod mills that were used in the application of dry grinding rod mills are 1. It is possible to extrapolate the performance of 5' and 6' diameter wet grinding rod mills into larger diameter rod mills with the larger mills performing as predicted. Wet grinding rod mills as large as 14' diameter (inside shell) by 20' long using 19.5' long rods are in use operating satisfactorily. 2. Wet grinding rod mills generally grind more efficiently when the fines are left in the mill feed than when the fines are removed from the feed. 3. Wet grinding rod mills produce little tramp oversize and generally can be operated in open circuit except when very close control on the top size in the product is required. When operated in closed circuit, the circulating load is normally less than 100%. 4. The power required for the desired grind can be accurately determined from the work indices obtained from rod mill grindability tests on the material to be ground. Where required it is necessary to, apply inefficiency factors for oversize feed and for larger or smaller than normal- ratios of reduction. Recent applications for rod mills have developed where it is required that dry grinding be used. These recent applications cover the grinding of 1. Lead sinter, lead slag and limestone. 2. Iron ore. 3. Silica for making glass sand. 4. Cement clinker. 5. Coke.

Jan 1, 1968

By Kozo Takeda, Arashi Shimano

"Dry Jet Mixing (DJM) method as the representative deep mixing technique has been demonstrating best practice on ground mitigation works coping with complicated soil condition and limited site space. This technique plays an important role in many projects to stabilize soft ground involving troubles like sliding failure, settlement, bearing capacity etc. Serious disasters caused larger earthquakes make great demand on the application of deep soil mixing these days. Special design and alignment of deep soil mixing has been established against to liquefaction and serious failure due to liquefaction. In this paper, representative example of liquefaction mitigation by DJM method is summarized. The paper also present result of surveillance of sites installed DJM col umns after attack by Tohoku Pacific Ocean Earthquake. Performance of DJM columns suffered the earthquake is demonstrated at several sites even with conventional column alignment.INTRODUCTIONThe DJM method is a representative deep soil mixing technique of dry mixing manner in Japan. DJM can successfully install soil mixing columns trough automatically controlled binder injection based on pneumatic feeding theory and cumulative experiences.This method was joint-developed in 1978 by private organization under initiative of the Public Works Research Institute of the Ministry of Construction as the optimum method for improving the Japanese soft ground. Figure 1 shows full view of the DJM construction system. Figure 2 illustrates DJM working system indicating Binder Feeding Plant side and Mixing Machine side respectively.As typical soil mitigation method, many projects related with rivers and roads and city development has required DJM technology. The total number of the projects applying DJM has exceeded 5,000 with the total treated soil volume more than 32,000,000 m3 by the end of fiscal year 2013."

Jan 1, 2015

By W. C. Meyer

Surface tension and its control are important in the concentration of ores by froth flotation, both in terms of producing the proper bubble size distribution and to render the ore surface of interest hydrophobic such that adhesion to a bubble will take place. The influence a substance has on surface tension has traditionally been measured using static, equilibrium techniques. Yet many applications such as flotation involve rate-related effects of surface tension where equilibrium values are not reached. In the time frame of 1 - 300 seconds, aging effects have been noted for bubbles formed in dodecylamine acetate solutions; a slow decrease in surface tension occurs until an equilibrium value is reached, as studied by Finch and Smith (1972). Since stationary bubbles do not exist in flotation cells because of the turbulence generated by agitation and aeration, it is more likely that the chemical composition of the bubble is determined during its formation, under dynamic conditions. The chemical composition is extremely important because the induction time required for a particle-bubble entity to collide and adhere to each other is augmented by favorable surface tension (wetting) proper- ties between the surface of the particle and the bubble air-water interface or envelope, as considered by Mackenzie and Matheson (1963). Finch and Lyman (1976) have established that the probability of a "permanent" attachment taking place during this contact time is aided by the ability of an oil droplet (viz. bubble) to relieve non- equilibrium surface tension effects which are involved in the water-thinning process. This Maragoni effect, or surface elasticity, can be considered in the context of particle agglomeration addressed by Kao and coworkers (1975). Water drainage leads to the formation of a collector-frother meniscus appearing between the colliding entities, arising from their combined partial immiscibility in the water phase and promoted by hydrophobic bonding within the interface. Together they constitute a liquid bridge whose force of attraction drawing the particles together is proportional to the interfacial tension existing between the water phase and liquid bridge. This adhesive force shows an approximate linear decrease with separation distance until rupture occurs, that is, FX = Fmax (1 ? X/Xr) (1) for a distance of separation X and rupture distance G. The greater the surface elasticity of the bubble, the greater will be the rupture distance and the better will be the force of adhesion. Since van den Tempel (1965) has related surface dilational properties of bubbles to the elasticity, E, of the film as

Jan 1, 1983

By R. C. Ford, W. L. Niccoli, J. B. Finley

All mining operations are superimposed on natural hydrologic systems. As a result, mining operations are influenced by natural hydrologic processes and require water management systems to successfully conduct mining activities. Managing water and mining-related solutions is a critical task at all stages of the mine life because of the time-dependent nature of natural and mining-related flows. Effective operation of the mining water management system requires a “systems” approach that integrates the time-dependent effects of all water and mine solution handling components. This paper discusses the concept and application of dynamic systems modeling to address the time dependent nature of mining water management systems.

Jan 1, 2002

By G. M. Dowo

The widespread environmental damage caused by slimes dam construction requires rehabilitation as one of the key management strategies towards land restoration. From the time when Mhangura Copper Mine in Zimbabwe was shut down in 2000 due to viability problems, no follow-up studies were carried out on the slimes dams to assess their development with respect to ecosystem function and longterm recovery. The ecosystem function analysis (EFA) method was thus employed to achieve this end. EFA is a monitoring procedure that establishes how well an ecosystem functions as a biophysical system through the use of rapidly assessed field indicators. The field procedure makes use of simple visual indicators that are related to various soil surface processes. Conventional sampling methods are used to collect the vegetation data. The data was first analysed using landscape function analysis (LFA) software packages and then with various multivariate statistical techniques. In total 27 species were recorded from 14 families; 21 of them occurring in the acacia woodland and only 8 on the slimes dams. Hyparrhenia sp. was the dominant grass on Dam 5 and Imperata cylindrica dominated Dam 6. Acacia saligna was the most abundant tree species on the dams. The tree layer on the slimes dams was not as developed as the grass layer. The rehabilitated slimes dams converged with the natural woodland for the LFA indices of stability, nutrient cycling, and infiltration, which suggested a high level of functionality. The main factors affecting the sustainability of the rehabilitation are postulated to be fire, grazing, and tree harvesting. The study contributed to the importance of, and methods used for, assessing ecosystem function on rehabilitated slimes dams in Zimbabwe, which are often ignored as most efforts focus on the establishment of vegetation on the dams. Keywords ecosystem function analysis, EFA, mine tailings, rehabilitation, monitoring, Mhangura Copper Mine, ecosystem function.

Dec 1, 2013

By K. H. Singh, J. N. Szuck, J. A. Riddell

"Hydraulic rock drilling equipment has been in use at Falconbridge over the past two years in both production and development situations. This paper deals with the experience gained in the application of hydraulic drilling in the company's mines and discusses the benefits and problems encountered during their use. The paper primarily focuses on technical, operating, maintenance and economic aspects of the machines, and does not attempt to compare the performances of different machines from the various manufacturers.IntroductionThe Sudbury Operations of Falconbridge Nickel Mines Limited are comprised of five operating mines and two mines under development. All the production comes from underground mines, mostly at depths below 1000 metres. The company, faced with increases in operating costs and difficult mining conditions, has continued to seek solutions with the help of new mining technology.The development of electric-hydraulic drilling machines in Europe had been pursued with great interest and, in 1979, a decision was made to test these machines to prove their technical and economic viability under operating conditions. Since then, a number of electric-hydraulic machines have been evaluated in different situations and currently nine hydraulic machines are being used in the company's various mines. These machines are comprised of two-boom drilling jumbos for development, one-boom machines for longhole drilling and a large-hole-diameter drilling rig for blasthole drilling. One hydraulic jumbo has also been used in a cut-and-fill stope."

Jan 1, 1982

By M. P. Tixier

Abstract In a review of the application of electrical logging in Canada, examples are .given of long and short distance correlations by means of the electrical logs. The use of MicroLogging for the determination of permeable and porous formations is explained. The question of log analysis for the quantitative determination of fluid saturation and porosity is .discussed. An example is provided to illustrate the significance of the resistivity gradient. The advantages of the new method of the Laterolog are shown, chiefly for the case of wells filled with high-salinity mud. Introduction Electrical logging techniques developed rapidly in Canada at the time an intensive drilling activity started for the exploitation of the Devonian series in Alberta, namely, at the beginning of 1947. The conventional service was soon thereafter supplemented with the latest technica1 improvements. Canada has been among the first regions to take advantage of MicroLogging*, which has proved a most powerful .tool for the investigation of permeable and porous formations; also, the more recent development known as the Laterolog has ?been introduced in Canada. The Laterolog provides a better determination of .the formations, particularly in the case of salty mud where the conventional logging is greatly handicapped. The various methods of electrical logging are now commonly known in oil industry and have been described in numerous publications ( 1) ( 2) (3).

Jan 1, 1951

By Susheel R. Kolwalkar

A significant increase in the side shear capacity over a period of time is often observed in case of driven piles. This phenomenon is referred to as ?setup? or ?freeze?. This phenomenon cannot be predicted based on the knowledge of the engineering properties of soil. Different kinds of mechanisms have been proposed in order to explain set-up in cohesive soils. In engineering practice, set-up is incorporated in design on the basis of empirical formulae and depends to a large extent on personal experience and judgment of the design engineer. Set-up is a natural process which cannot be accelerated by any existing practice. A research was initiated to investigate the mechanism of pile set-up in clayey soils and explore the possibility of accelerating the set-up process by an electro-kinetic method. The system chosen for the present study consists of a prototype steel pile driven in kaolinite clay. A laboratory test program was developed at Cleveland State University in order to meet the goals of the proposed research. Results obtained from these tests are very encouraging and show pile capacity increase of 200% within the first 5 days of electric gradient application versus those that experience natural set-up. In this paper, theoretical considerations and laboratory test results are presented and discussed.

Jan 1, 2008

By L. Ya Agapova

Emissions from pyrometallurgical processing of copper concentrates are usually subjected to wet scrubbing. The washing sulphuric acid so produced contains up to 0.2 g/L of rhenium, which is recovered by solvent extraction in the form of crude ammonia permeate (NH4ReO4). The mother liquor, obtained from the sulfuric acid wash, contains up to 35 g/L of rhenium and significant amounts of impurities. Crude rhenium salt is commonly processed by double recrystallization to produce marketable salt. A ton of high grade NH4ReO4 can be produced using 3.0-3.5 m3 of mother liquor. We propose an efficient technology of mother liquor pre-treatment aimed at removal of water-soluble organics with subsequent electrodialysis. Electrodialysis of mother liquor in a multichamber electrodialyzer resulted in the production of pure rhenium acid, from which a marketable NH4ReO4 is precipitated using ammonia solution. Multiple steps of recycling consisting of dissolution of NH4ReO4 salt, rhenium acid production from NH4ReO4 salt by electrodialysis and precipitation of NH4ReO4 from rhenium acid made it possible to upgrade the purity of obtained rhenium compounds by 1-2 orders of magnitude. A rhenium metal powder of 99.997% purity was produced by high-temperature reduction of high-purity NH4ReO4 with gaseous hydrogen. Rhenium metal powder of high purity can be produced from sulfate solutions of NH4ReO4 by non-platinum anode-based membrane electrolysis processes also. Keywords: rhenium, mother liquors, membranes, electrodialysis, rhenium acid, ammonia perrhenate, reduction, powder, electrolysis

Sep 1, 2012

By Krzysztof Kotwica

The steady demand for rock materials leads not only to on increase in mining but to the need for decreasing the loss of material in the process of exploitation as well. It brings about an increase in using of explosives in open pits and as a result an increase of after blasting gases volume, vibrations, the scattering (dispersion) of stone ect. All these factors affecting the environment lead to the research work for applying the electrohydrodynamic methods both in open casts and underground mines. In the article the authors describe the concept of this method and construction of equipment which recently have been successfully introduced in mining, the results obtained determine the possibilities of using this method and the future directions. The results of combined method with high-pressure water jets cutting and prototype equipment for separating rock blocks from the rock mass using special head with high-pressure water jets are also described.

Jan 1, 2006

By F. Keller, A. H. Geisler

Some of the important changes that take place in the structure of aluminum alloys are largely submicroscopic in character. This is especially true of the changes that accompany age-hardening and recrystallization. Although improved metallographic practices have been helpful in indicating some of these changes indirectly, results are limited by the resolving power of optical microscope lenses. The electron microscope, however, provides a new and important means for investigating the fine structure of metals in a range not possible heretofore. It is anticipated that this microscope will yield new and useful information to metallurgists when suitable techniques are developed to utilize its very high resolving power. Several unique methods have been devised to permit the examination of the structure of opaque samples by the electron microscope. These are all based on the principle of producing a very thin film that represents the prepared surface of the opaque metal sample, which can be examined in the transmission microscope; however, the available methods fall into three categories, depending on the manner in which the film is obtained. With the oxide-film method developed by Mahl3-17 a very thin surface layer of the metallographic sample is converted into oxide by a thermal, chemical or anodic treatment. After removal from the metal sample by one of the special techniques described by Evans,19 this oxide film is examined in the electron microscope, and is found to portray the structure of the original metal surface. Films formed on aluminum,8,17 nickel,7 iron 3,8,9 and a nickel-beryllium alloy" by heating; films formed on iron 8.9 by chemical action; and films formed on aluminum3-16 by anodic oxidation, have been examined. The other two are more recent methods developed principally in this country; they consist in making the thin film in the form of a mold or replica of the surface contour of an etched sample. With the negative replica method the thin film is made directly on the sample; with the positive replica method it is made on a negative reproduction of the sample. With both methods, variations in the contour of the metal sample, caused mainly by etching, produce variations in the thickness of the surface replica. Because of the direct dependence of the amount of scattering of the illuminating electrons upon the thickness of the film penetrated, only the variations in thickness of the replica are responsible for tones in the electron image. Negative replicas are made by forming a thin film of some suitable material directly on the polished and etched metal sample, and derive their name from the fact that after removal from the sample they have the high and low points in the sample reversed, as shown in Fig. I. Nega-

Jan 1, 1944

By R. ?. Shishmarjov, Yu. ?. Davidenko, S. V. Bukhalov, ?. S. Baksheev, M. S. Shkirya, N. ?. Aikasheva, D. V. Bogdanovich, ?. Yu. Faustova

"The goal of prospecting operations in the Republic of Altay was to locate gold-sulfide-quartz mineralization. For this purpose we applied the technology of electromagnetic sounding and induced polarization (EMS-IP). These operations resulted in localizing promising sites with presence of sulfidization. The EMS-IP method proved to be highly efficient amongst other prospecting methods targeted at recognizing zones of sulfide mineralization making up 91%, considering that in more than half cases the ore intervals were the case. In the Yakutian diamondiferous province the EMS-IP technology was approbated during three field seasons to accomplish the assignments on searching for kimberlite bodies under conditions of various geological types. As a result, the reference objects were distinguished, and geoelectric parameters of kimberlite pipes of explosion were defined.INTRODUCTION In the time span 2015-2016 in Gorny Altay the EMS-IP technology was approbated in the Novokuznetsk area. The on-land areal geophysical survey was performed by EMS-IP method applied to identify, outline and locate promising sites with Au-Ag-bearing polymetallic mineralization within surveyed areas. Compared to the hosting rocks, the sulfides contained in polymetallic mineralization are typified by low specific electrical resistivity (SER) and high polarization. The areal survey conducted via EMS-IP method provided spatial characteristics of searched object. From July 2016 to August 2017 our expedition group carried out serial test works and laboratory investigations intending to define performance capabilities of EMS-IP technology in searching for kimberlite bodies under conditions of diverse geological types. The prerequisites for serial work were operations accomplished at the «Listvenichny» site lying 35 km away from Mirny town in the Sakha Republic (Yakutia), where the EMS-IP technology was probed for locating position and measuring geoelectric parameters of tuff pipe «Buardakhsky». After successful completion of operations it was decided to evaluate geoelectric parameters of kimberlite pipes of explosion."

Jan 1, 2018

By A N. Gupta, C Joginadham, P Shiva Shankar

Cast boosters made with pentaerythritol tetranitrate(PETN) and trinitro toluene(TNT) give high velocities of detonation and are sensitive to initiation even under high pressures. However, the manufacture of the same involves heating of TNT to its melting temperature and mixing of dry PETN in it.

Jan 1, 1996

By W R. Adamson

"Optimisation of drill and blast design and engineering can deliver a significant positive impact on the profitability of any mining operation; however, true engineering of the blasting process is less common than might be thought. The paper that follows explores this gap and suggests a process control-based approach to the challenge.The concept of applying modifications to drill and blast designs in order to achieve efficiency improvements in downstream mining processes is far from new. However, the author suggests that the practical application has become less than rigorous in a number of different sectors of the mining industry in a wide range of countries.There is a common tendency for the design process to become simplified to the point where the objective is merely the communication of instructions to field implementers (drillers, explosive suppliers, blasters, etc). In effect ‘design’ often degrades to ‘cut and paste’ with consequences that vary from mild to critical, with respect to the profitability of the business.Engineering of the drill and blast process involves the design function, not on a one-off basis but rather as a component of a more complete cyclical process that includes a statement of objectives, a design based on a suggested hypothesis, field measurement of results, comparison with the target ‘set point’ and the application of control measures followed by new measurement, including interpretation of the results in financial terms.When applied in this fashion, engineering provides practitioners with the means to optimise the drill and blast impact on the full spectrum business result of the mining activity.These concepts are discussed with reference to a surface gold mining operation applying run-of-mine heap leach extraction. Engineering optimisation by adapting process control and measurement techniques is demonstrated to be a key component of the solution set applied to generate enhanced operations productivity and stakeholder value. It is shown that a combination of rigorous measurement, model calibration and hands-on quality assurance/quality control facilitates the creation of a road map to profitability, stressing the need to consider economic trade-offs between operational expense (investment) and measurement of enhanced value (return on investment).The process, however, does not cease at this point. Implementation of true design practices, incorporating innovation and discipline in implementation or execution can drive the process to deliver demonstrable, technically validated outcomes. Furthermore, these technical results can be related to financially quantifiable impacts. However, this accomplishment does not guarantee that these gains or savings will reach the bottom line of those mining, quarrying and construction companies that begin the process with such high hopes.CITATION:Adamson, W R, 2015. Application of engineering discipline and a full-process optimisation focus – productivity to profitability without profuse pruning, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 3–12 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Aug 24, 2015

By J Pan

This case study assesses the application of Mine-to-Mill optimisation combined with Whittle Consulting’s Prober<sup>®</sup> economic optimisation for the purpose of economic value uplift in open cut base and precious metal operations. The study extends the application of these optimisation methods to incorporate the recent practice of Ultra High Intensity Blasting (UHIB) developed by Orica Mining Services. The case study deposit known as “Marvin” is a copper/gold porphyry resource that is commonly used in optimisation software training and industry case studies. It has many similarities to Newcrest’s Cadia Hill open pit mine in NSW. Prior desktop research and industrial trials employed static assessments of Mine-to-Mill effects. No prior work other than a Whittle Consulting client study, has sought to assess the impact of variable fragmentation on enterprise economic value. This study examines the use of variable blasting intensity as a driver of economic value maximisation over the mine’s life.CITATION: Howe, S and Pan, J, 2018. Application of enterprise optimisation considering ultra high intensity blasting, in Proceedings Complex Orebodies Conference 2018, pp 14–20 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

By B. Salopek, D. Rajkovic, D. Rumenjak

In decision making support system, that are used in various fields of environmental protection (environmental impact assessment, environmental management systems, setting environmental standards and regulation, etc.), it is often important to apply various mathematical environmental engineering models. The question of linking environmetal engineering modeling to decision making support system used in environmental protection is not yet methodically solved. The reasons for that could be manifold. Decison making support systems, used in environmental protection, because they are simply taken from bussines decision making, are not often adequate for specific problems raised in environmental protection. On the other hand, there are great number of types of models in environmental engineering, what urges the problem of finding the way of their proper linking with decision making support systems. The application of fuzzy logic in that field is estimated as one of possible solution of the problem.

Jan 1, 2005

By Christopher D. Henry

Environmental geologic maps of the Wilcox and Jackson-Yegua lignite belts of the Texas Coastal Plain delineate land areas on the basis of their natural characteristics. Criteria used to define map units include substrate, soil, topography, geologic process, vegetation, and land use. The maps are useful in planning and reclamation of lignite mines and in meeting the requirements of State and Federal surface mining laws. Specific applications include identification of land capability, recharge areas and geometry of aquifers, flood-prone areas, areas that may qualify for prime farmland status, and other areas sensitive to lignite mining.

Jan 1, 1982

By T. Asahina, M. Nakamura, M. Mabuchi, I. Shigematsu, M. Nakanishi, G. Yamauchi

"Commercial stainless steels (SUS304L and SUS430) were subjected to equal channel angular extrusion (ECAE) at room temperature to a total strain of 2.3 to 9.2. For each type of stainless steel, it was shown that the sample processed by ECAE showed higher room temperature strength than the as-quenched sample. This is probably due to the heavily worked structure. On the other hand, both strength and elongation of the ECAE processed SUS430 were increased by annealing at 773K. It is likely that higher strength is attributed to both the heavily worked structure and fine substructures. It is also likely that higher elongation is attributed to the fine substructures. It is concluded that ECAE is available for improving the room temperature strength of commercial stainless steels.INTRODUCTIONEqual channel angular extrusion ( ECAE ) is a technique that provides the repetitive deformation and allows to high intensity of deformation. With this procedure, a sample is pressed through a channel that has an equal cross section but bent at an angle of ?> [1-2]. Shear strain is introduced when a sample passes through the bending point of the channel. Repetitive processing is feasible because the cross-sectional dimension of a sample has no change during processing. To date, many reports have described that ECAE is available for the fabrication of fine-grained materials [3-14]. On the other hand, an ECAE processed sample can achieve high intensity of deformation through repetitive deformation. According to the equation given by Segal [ 2 ], a strain of about 1 is introduced in each pass through die if the angle ? is 90 deg.It is well known that high tensile strength can be achieved in metallic materials through work hardening [15]. It is also known that metallic materials with fine grain size show high strength [16]. Hence, it is expected that ECAE is available for strengthening method in metallic materials. In the present paper, we will report the mechanical properties of stainless steels processed by ECAE. As samples, SUS304L austenite stainless steel and SUS430 ferritic stainless steel were chosen. Each alloy has a single-phase structure (fee or bee) and shows no phase transformation, so that transformation strengthening cannot be applied. Hence, a heavy cold work such as ECAE may be effective for strengthening of this stainless steel. Annealing was conducted for the ECAE processed SUS430 to vary its microstructure. Then, the effect of annealing on the strength of the ECAE processed SUS430 was also investigated."

Jan 1, 2000