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By H. Asgari, A. G. Odeshi, J. A. Szpunar

In the present study, the dynamic response of AZ and AE cast magnesium alloys to shock loading, are compared for strain rates ranging between 900 and 1200 s-1. Texture measurements showed that after shock loading, the (00.2) basal texture component of both alloys was strengthened. However, the strengthening magnitude was higher for AE samples. Also, it was observed that the twinning fraction decreased in both alloys with increase in the amount of alloying elements. In addition, cracks are formed at the interface between matrix and second phase particles in the AZ alloys. However, crack nucleation and fracture in AE alloys occurred at the sites where twins accumulated. Furthermore, analysis of the dynamic mechanical behaviors showed that the ductility of AE grade is higher than that of AZ alloy for all strain rates used in this research. This difference was explained by differences in deformation mechanisms of these alloys.

Jan 1, 2014

By Z. Gxowa, L. H. Chown, U. Curle, G. Govender

This work evaluates the deformation behaviour, at warm working temperatures, of green particle-reinforced aluminium composites produced by powder blending in a high-energy ball mill. The work focuses on metal matrix composites (MMCs) based on the 2124-Al alloy, reinforced with 10 or 15 vol.% SiC and metal matrix nanocomposites (MMNCs) based on the 2124-Al alloy, reinforced with 5 or 10 vol.% Al2O3. Three batches for each powder were blended and powder properties such as particle size distribution (PSD) and shape were consistent after blending. It was observed that a more uniform distribution of the reinforcement phase in the aluminium alloy matrix was achieved in 2124-Al/Al2O3 than in 2124- Al/SiC composites. The powders (unreinforced 2124-Al and blended) were initially over-aged at 350°C for 2 hours to reverse any natural ageing that may have occurred prior to use. The over-ageing was incorporated to improve compressibility of the powders with the aim of achieving green compacts with higher integrity. Uniaxial compression tests performed at ambient temperature on a Gleeble® 3500 thermomechanical simulator were unsuccessful as the green compacts fragmented. Engineering stress-strain curves showed that green compacts of unreinforced 2124-Al, 10%SiC MMC and 5%Al2O3 MMNC deformed in a similar manner at ambient temperature and had the same compressive fracture stress of approximately 170 MPa. When the deformation temperature was increased from ambient to warm working temperatures (170–280°C) it was observed that electrical resistance heating (the heating mode of the Gleeble®) of unreinforced Al alloy, MMC and MMNC green compacts did not occur. This was attributed to the high electrical conductivity of aluminium, which resulted in poor heat generation due to the low electrical resistance in the samples. It was presumed that the small sample size (d=8 mm, h=12 mm) also caused rapid heat loss. After further experimentation, the green compacts were heated successfully by insulating the samples to retain heat. It was found that at 280°C, increasing the soaking time from 6 to 20 minutes decreased flow stress and improved plastic flow in the 2124-Al/10%SiC green compact.

Jan 1, 2016

By X. Yu

Although many investigations of the deformation behaviour of rocks have been carried out, most of them are carried out in compression. In all rock engineering practice it is usually assumed that the deformation of rocks in tension is the same as that in compression. However, data from numerous researchers have shown that this assumption is not correct for some rocks. A new loading frame for testing rocks in compression and direct tension has recently been developed by the authors, with the capacity to conduct both compression and tensile tests on the same rock sample. The results obtained show that the ratios between the average Young?s modulus in compression (ECA) and in direct tension (ETA) are 1, 1.16, 2 and 6 respectively in four rock types tested. For Poisson?s ratios, analogous relations were obtained. It was observed that, in all cases, the tangent Young?s modulus intension reduces with an increase in the applied tensile stress, while the behaviour of Poisson?s ratio is similar, but shows greater variability. The difference between the Young?s modulus of rocks in tension and that in compression could lead, large errors in calculating induced stresses around underground openings, as well as in determining the Brazilian tensile strength of rocks. This may have a significant influence in rock engineering and therefore more investigation is necessary into the tensile deformation behaviour of rocks and its influence.

Jan 1, 2005

This paper describes the behaviour, under creep conditions, of a cast lead creep specimen consisting of five crystals, the boundaries of these crystals being substantially at right angles to the direction' of tension, i.e., across the long axis of the specimen. This particular specimen was obtained in an attempt to produce a single crystal in the manner described in the appendix of a previous paper (1).Thus, the specimen was of the same shape and size, was composed of the same purity lead and received the same preliminary treatment as the single crystal test-pieces.The object of the experiment was mainly to observe the effect of the crystal boundaries on both the deformation of the test piece and the process of recrystallisation and to compare the creep rate of the test-piece with that of a specimen consisting of one crystal only.EXPERIMENTAL METHODThe specimen had an effective test length of 10 cms. and a cross $ection of 0·5 in. x 0·25 in. In Fig. 1 is given a sketch of the specimen to scale showing the positions of the crystal boundaries on all four surfaces. Except for those of crystal No. 4, which was confined to approximately one-half the cross section of the specimen, the boundaries of each crystal traversed the four faces.The specimen was mounted in exactly the same manner as the single crystal specimens. During the creep test, it...

Jan 1, 1941

By C. Zangerl, W. Fellin, M. Holzmann, B. Hofer, S. Perzlmaier

"Four deep-seated rockslide systems were investigated and are under surveillance by TIWAG (Tyrolean hydro-electric Company) since the mid-1960s after impoundment of Gepatsch reservoir began. These rockslide systems consist of several individual sliding masses (slabs) which show variable activity from zero to a few centimetres per year. The focus in this paper will be on the findings for the transient deformation behaviour of the Hochmais slab which is part of the “Hochmais-Atemkopf” rockslide system.The rock mass has slid over moraine deposits in the last post-glacial period and was in equilibrium (or slow to extremely slow moving, respectively) until the filling of the reservoir began. During the initial reservoir filling in summer 1964 considerable movements had been observed over a length of 1000 m accompanied with an activation of the Hochmais slab. Geological investigations, additional surface and subsurface measurement showed that the sliding mass is characterized by an en bloc movement and the deformation accumulates within a several metre thick shear zone located within the moraine. In contrast to the deformation characteristics for the first impoundment process (1964 – 1966) where the magnitude of deformation occurred during impoundment, the maximum amount of deformation since 1967 occurs during the drawdown of the reservoir. Based on long term measurement it can be shown that the magnitude of deformations per year correlates with the minimum storage level in the reservoir. Other external influences such as precipitation and snowmelt have no observable impact on the deformation characteristic of the landslide. On the basis of long-term data series it was possible to determine the factors of influence and to elaborate a conceptual mechanical model which describes the transient deformation behaviour of the Hochmais slab induced by the drawdown of the reservoir. The mechanical model considers the reduction of uplift forces in the highly fractured and permeable rock slab during drawdown as well as increasing seepage forces in the less permeable moraine material."

Jan 1, 2015

By E. Yasar

This paper describes the use of the sand and plaster physical modelling technique to investigate the deformation around mine roadways using a variety of support methods in a particular form of stress field. The characteristics and conditions of coal measures rock were considered prior to the preparation of the models and the insertion of support The investigation has clearly shown how floor lift, roof failure and sidewall movements of mine roadways in laminated weak rock conditions gradually develops as a result of the increase in the stress and, also, how it is related to the level of support used.

Jan 1, 1995

By S J. Chen, N Jiang, Y S. Ding, F X. Li, D W. Yin, F Wang

This study assessed the deformation failure characteristics of rock-coal composites with different height ratios. Uniaxial compression tests were conducted using an acoustic emission monitoring system and XTDIC three-dimensional full-field strain measurement system. The results showed that with the increase in rock-coal height ratios, the uniaxial compressive strength of composite samples increased from 5.26 MPa to 14.61 MPa. The evolution of the deformation localisation zone of the composite samples is closely related to the initiation and propagation of the primary cracks in the coal samples. At the moment when the main fracture of the coal samples occurs, there is a large drop after the peak of the stress-strain curve of the composite samples, and the height of the rock samples increased to varying degrees, which indicated that the failure of the coal samples induced the rebound deformation of the rock samples. With the increase in rock-coal height ratios, the rebound deformation amount of the rock samples decreased from 0.042 mm to 0.008 mm, and the rebound deformation rate decreased from 0.210 per cent to 0.010 per cent. Meanwhile, the rock samples’ rebound deformation releases part of the elastic energy to act on the coal sample, further contributing to the destruction of the coal samples. Compared with single composite coal samples, the coal samples of the composite samples have much more failures. In addition, with the increase in rock-coal height ratio, the input energy density, elastic energy density, post-peak release energy density, and residual elastic energy density of the composite samples increased, the dissipation energy density decreased, and the percentage of pre-peak elastic energy density increased from 98.56 per cent to 99.86 per cent. These results revealed the deformation failure characteristics of rock-coal composite with different height ratios and provided a theoretical reference for understanding the underground dynamic rock failures.

Nov 29, 2022

The Warraua and Mount Poole Inliers form part of a discontinuous series of basement complexes in the northwestern corner of New South Wales. The Inliers comprise mainly clastic sediments of low metamorphic grade (Wonominta Beds) and minor sills, dykes and intrusives, particularly within the Mount Poole lnJier. The Warratta rnlier has received attention due to the occurrence of auriferous quartz-veins where reef mining activities havetaken place.The deformational history of the Warratta and Mount Poole Inljers is characterised by a continuous subhorizontally WSW-ENE directed compression. Deformation was associated with the development of NNW-trending and steeply west-dipping major faults, which bound or biscct the inliers. Chevron folds and a penetrative axial planar cleavage characterise the deformational architecture and document crustal shorterung of at least 40 per cent. In zones adjacent to the major faults and within pelitic and semi-pelitic uruts, a multiple deformational evolution becomes apparent, comprising two events (D1 and D2). Deformational structures considered significant in this study were the result of D1. Tight, northeast-vergent fold patterns FI' and associated axjal plane cleavage SI' and reverse dip-slip movements at major faults indicate early northeast-directed thrusting during D1. This was followed by dextral strike-slip deformation displayed by tight, recumbent folds, en-echelon fold patterns (F2'), a northeast trending crenulation cleavage (52'), and two sets of second order faults, the latter showing high angular relationship to the major faults. A final stage of the deformational history (D2) is represented by WSW-ENE trending kink folds (F2).Auriferous quartz veins, predominantly occurring within pelitic and semi-pelitic units, were generated syntectorucally during the early deformational event (D1) in the course of commencing development of cleavage (S2'). Vein textures point towards vein formation by repeated hydrauJjc fracturing and fracture healing (crack-seal process), and by simple accretionary vein growth. Folded pelite-dominated horizons, considered as low permeability units, are suggested preferential sites where migrating metamorphic Ouids pooled and were trapped, causing high fluid pressure.Hydraulic fracturing and vein precipitation was controlled by lithology and structural constraints such as cleavage.K-Ar dates of approximately 440 Ma (Benambran Orogeny) marking the peak of metamorphism, and coinciding with the development of cleavage S1', also indicate the time of auriferous quartz-vein formation. A period of deformation of at least 30 Ma is proposed for the development of cleavage S1', as constrained by K-Ar dating and the intrusion of a syntectonic granitoid, the Tibooburra Granodiorite.

Jan 1, 1992

By H. P. Moore, R. W. Fenn, Harold Margolin, W. R. Hibbard

DEFORMATION lines, also called etch markings or strain markings, are noneffaceable lines developed in individual grains by etching a metal specimen which has been cold worked sufficiently to cause atomic non-conformity or slight orientation differences within the grains. Etching occurs more rapidly at these lines of high chemical reactivity to produce a result similar to that revealing grain boundaries.1 Wider etching effects forming bands have been found. They are believed to be bands of deformation lines which form areas of measurably different orientation from the crystal matrix. The crystallite rotations causing these bands have been shown by Barrette to contribute to deformation textures. Although deformation lines have been observed in many metals, the amount of deformation required for their appearance has been established only in general terms. Mathewson and Phillips3 observed the first appearance of deformation lines in cold-rolled alpha brass at about 20 pct reduction in thickness using the standard ammonium hydroxide hydrogen peroxide etchant. Price and Davidson4 noted deformation lines in common high brass after 26.5 pct reduction by cold rolling using the same etchant. Johnson' observed dark thick forklike lines in 99.99 pct pure copper reduced 31.8 pct. Adcock6 observed deformation lines in 80-20 copper-nickel alloy rolled 50 pct. Samans7 found no deformation lines in alpha brass single crystals cold rolled 9.5 pct but they did appear after 25 pct reduction using ammonium hydroxide and hydrogen peroxide etchant. Barrett and Levenson8 observed deformation bands in drawn polycrystalline iron at very small reductions in area and noted that their initial appearance perhaps depends on grain size and other conditions. They reported deformation bands in a single crystal of iron reduced 6 pct by drawing. Brick9 noted that deformation lines in 70-30 brass apparently associated with {111} planes appeared after reductions of from 20-50 pct by cold rolling. Brick and Williamson10 noted that in single crystals of 70-30 alpha brass "as in polycrystalline brass, no deformation markings appeared until reductions exceeded 20 pct." Cook and Richards11 reported that in copper cold rolled less than about 50 pct few strain markings were apparent but for higher. reductions many strain markings appeared transverse to the rolled direction. In a review article Brick and Phillips12 noted that previous studies had not shown deformation lines in cold rolled alpha brass

Jan 1, 1948

By I. Weir-Jones

I. Introduction The experimental work described in this paper was carried out during 1967 and 1968 in an inclined reinforced concrete adit which had been driven during 1965 and 1966 to provide primary access for a new gypsum mine. The new mine was situated near the village of Sherburn-in-Elmet in central Yorkshire in an area of extensive post-glacial plains of deltaic and lacustrine origin. These plains cover a large area of this part of Yorkshire extending inland from the coast for a distance of about 35 miles. The gypsum deposit at Sherburn dates from Permian times and it is considered" to have been associated with the western-most edges of the ancient Zechstein Sea which was also responsible for the formation of the extensive evaporite deposits in north-east Yorkshire. The gypsum deposit, which varies in thickness from 10 to 15 feet, is extremely pure and it occurs quite close to the surface; in the Sherburn area the overburden is only 120 feet thick. The proximity of the deposit to the surface, however, tends to give a somewhat false idea of the magnitude of the problems associated with its extraction. These problems were all related to the nature of the overlying strata. As has already been mentioned, the surface deposits are post-glacial and they consist of an extremely large number of thin layers of varved clays, fine silts and sands extending down to a depth of 75 feet. From the bottom of the post-glacial deposits to the seam, a distance of about 45 feet, the strata consists of a succession of marls, weak sandstones, and siltstones, which although they are inherently incompetent materials, are appreciably stronger

Jan 1, 1971

By Xicai Gao

With the intensification and expansion of deep coal mining, the surrounding rock stress environment becomes further deteriorated because of the complicated geological environment and powerful mining effect, so the major deformation of roadway appeared frequently. The proportions of floor heave are increasing and , the most serious problem is the floor heave of preparatory workings. The coal seam of Binchang coal area in Shaanxi province is at a depth of 621.6 ~ 817.0 m, the average thickness of the coal seam is 25 m, and the overburden and coal measure strata are the main regional aquifers and are highly permeable. The properties of water-weakening are obvious in the floor strata. The main preparatory workings or chambers were driven in the coal seam. The severe floor heave of the water chamber appeared during early mining and the amount was 180 ~ 910mm, and seriously affected the normal installation and use of the water chamber. Theoretical study and numerical simulation as well as the in-situ measurements were carried out to investigate the deformation and failure characteristic of the surrounding rock with non-support in the floor and the main reasons which caused the floor heave were determined. A new combined support technology was proposed which consists of overcutting, grouting, backfilling and invertedarch and bolt-grouting. The field monitoring showed that the cumulative convergence of the water chamber was 20mm, the maximum convergence speed is 1.2 ~ 2mm/d, the accumulative convergence of two ribs was 36mm and the maximum convergence speed is 2mm/d. The combined support technology will enhance the support intensity between the roof and floor, the two sides of the entry and improve the loading capacity of the floor effectively and the floor heave can be controlled effectively.

Jan 1, 2013

By J. Handin, S. J. Bauer, M. Friedman

Deformation mechanisms in room-dry and water-saturated specimens of Charcoal Granodiorite, shortened at 10-4s-1, at effective pressures (Pe) to 100 MPa and temperatures to partial melting (?1050°C) are documented with a view toward providing criteria to recognize and characterize the deformation for geological and engineering applications. Above 800°C strength decreases dramatically at effective pressures ? 50 MPa and water-weakening reduces strength an additional 30 to 40% at Pe = 100 MPa. Strains at failure are only 0.1 to 2.2 percent with macroscopic ductility (within this range) increasing as the effective pressures are increased and in wet versus dry tests. Shattering (multiple faulting) gives way to faulting along a single zone to failure without macroscopic faulting as ductility increases. Microscopically, cataclasis (extension microfracturing and thermal cracking with rigid-body motions) predominates at all conditions. Dislocation gliding contributes little to the strain. Precursive extension microfractures coalesce to produce the throughgoing faults with gouge zones exhibiting possible Riedel shears. Incipient melting, particularly in wet tests, produces a distinctive texture along feldspar grain boundaries that suggests a grain-boundary-softening effect contributes to the weakening. In addition, it is demonstrated that the presence of water does not lead to more microfractures, but to a reduction in the stresses required to initiate and propagate them.

Jan 1, 1982

By S J. Clarke, C S. Walker

The South West Rail Link (SWRL) project involved construction of a rail line to service new residential areas in south-west Sydney. The 11 km rail line is conveyed through a short tunnel at shallow depth where it crosses beneath the eight lanes of the Hume Highway. The underpass location is one of the most heavily trafficked within Sydney’s motorway network.The New South Wales Roads and Maritime Services (Roads and Maritime), as the owner of the highway asset, had the responsibility of managing the risks to the highway and traffic associated with the tunnelling project from the pretender stage through to completion. This paper considers the primary risks and mitigation measures employed, including geotechnical investigation, and development of appropriate construction constraints and concept design of an extensive real-time survey system to monitor pavement deformation during the tunnel works.The geology comprises fresh Minchinbury Sandstone in the tunnel invert and side walls, and variably weathered Bringelly Shale in the haunch and crown. Few tunnels have been excavated in these rock types in Sydney, and there is little information relating to the in situ stresses and stress-relief deformations in these materials.During tunnel construction the monitoring data indicated unexpected surface heave of up to about 24 mm. A multiparametric back-analysis of the deformation data is presented, which provides information on the deformation mechanisms and key geotechnical parameters, including rock mass modulus and in situ stresses.The approaches and methodologies developed for the SWRL underpass were effective in maintaining the safe operation and traffic capacity of the highway throughout the construction period, and the analysis of the monitoring data provides a useful reference for similar future projects, or projects constructed in similar ground conditions.CITATION:Clarke, S J and Walker, C S, 2014. Deformation mechanisms of the South West Rail Link underpass beneath the Hume Highway, in Proceedings 15th Australasian Tunnelling Conference 2014, pp 631–640 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By J. Daniel Bryant

Deformation processing of rapidly solidified powder alloys presents a technical challenge different in several ways from the processing of ingot based alloys. The metastable phases formed during planar flow casting of aluminum alloy 8009 (FVS0812) must be safe-guarded from high temperature excursions during processing to avoid decomposition; this restriction prohibits liquid phase sintering of particles during consolidation. The development of strong particle-particle adhesion, therefore, relies on the imposition of very large strains during forming operations to insure sufficient mechanical meshing of the aluminum particles and break-up of prior particle oxide boundaries. These strains are generally much greater than those required for metallurgical transformations in ingot based alloys. In an attempt to quantify the deformation required to improve interparticle bonding, the finite element method (FEM) was employed. Preliminary results which predict the metal flow and strain distribution in several workpiece configurations are discussed. These predictions are then correlated to measurements made on experimental subscale forgings. Lastly, experimentally measured quantities which reflect the degree of interparticle bondingg are related back to FEM model predictions.

Jan 1, 1992

By Sadtler, C. B.

IT is generally assumed that in most metals and alloys a given tensile stress produces a given deformation irrespective of the length of time during which the stress is applied. This assumption is justified in most of the important engineering applications of metallic materials; however, in the case of some metals and alloys used or tested at temperatures over or slightly under that at which recrystallization can occur the assumption is not warranted.1 This paper deals with the variations of deformation produced by a constant tensile stress acting for varied lengths of time in the special case of thin aluminum alloy sheet of the duralumin type, which had been subjected to different thermal and mechanical treatments. The material investigated was in the form of a sheet approximately 0.002 in. thick, which had been cold-rolled from a thickness of 0.020 in. It has been found that at a sufficiently high constant tension such material deforms continuously with the elapse of time and that the rate at which this deformation occurs is greatly influenced by the previous thermal and mechanical treatments.

Jan 1, 1927

By Seokbin Lim

In the design of explosives devices, an understanding of the behavior of explosively propelled matter is one of the most important steps in maximize the performance of these devices. For instance, an explosively driven metallic liner in LSCs (Linear Shaped Charges) creates its functional effect of penetration after a finite distance of travel (before collapse), thus the detailed study of the projection mechanism of the flat liner after detonation helps in the optimization of the design of LSCs. In a typical metallic flyer driven by explosive detonation, the detonation gas propels nearby matter including flat flyers. After a certain degree of expansion in the detonation gas, the flat flyer reaches its maximum velocity and slows down afterward. These typical behaviors are well investigated and numerically studied by many researchers. However, the rarefaction intrusion (detonation gas expansion) near the surface of the explosive charge creates significant deformation of the flat flyer , and produces U-shaped bending or deformation near the edge of the flyer during projection, creating unexpected behavior in explosive devices of interest. In this paper, a preliminary investigation of a localized Ushaped deformation of flat metallic flyers during projection is studied utilizing a theoretical approach and computational modeling facilitating an understanding of a general tendency of the deformation behavior.

Jan 1, 2010

By Alden B. Greninger

IN a recent study1 of the deformation of metastable beta copper-zinc and beta copper-tin crystals, it was established that the parallel markings that appear on the surface of these crystals after slight deformation represent lattice transformations. Stereographic analysis showed that in beta copper-tin, the poles of these markings deviated one or two degrees from poles of the form 1133). In beta copper-zinc the plane delineated by the markings corresponded to no one crystallographic plane of the matrix lattice; the marking poles deviated from 5° to 11° from poles of the form {110}, and were displaced only a few degrees from (110) zones. Inasmuch as the new transition lattices produced as the result of the deformation are different for each alloy, it was thought at first that the habits of the markings might be the result of a cooperation between matrix lattice and transformed lattice. (Both matrix lattices are body-centered cubic.) Such a cooperative effect is thought to obtain in the formation of Widmanstätten figures, for it is well known that the matrix lattice alone does not determine the habit assumed by a segregate phase. On the other hand, it is not inconceivable that the dissimilarity in marking habit might be due to differences in deformation characteristics of beta brass and beta bronze. Barrett and co-workers2 have shown that slip-line habits in pure iron are markedly different from those in high-silicon ferrite; and although it has been repeatedly demonstrated that plates of a segregate phase do not necessarily form on the slip planes of the matrix lattice, deformation characteristics may be more intimately allied with plate formation when a transformation is made to occur as a result of plastic deformation. However, there is the fact that the orientation of markings in metastable beta copper-zinc is the same whether the markings be produced by quenching, deformation, or liquid-air cooling; likewise, quenching and deformation markings in metastable beta copper-tin are oriented in the same way with respect to the beta matrix. During the course of the investigation referred to above, samples of 52:48 (stable beta) copper-zinc f were deformed and examined micro-

Jan 1, 1938

By Alden Greninger

IN a recent study1 of the deformation of metastable beta copper-zinc and beta copper-tin crystals, it was established that the parallel markings that appear on the surface of these crystals after slight deformation represent lattice transformations. Stereographic analysis showed that in beta copper-tin, the poles of these markings deviated one or two degrees from poles of the form { 133 } . In beta copper-zinc the plane delineated by the markings corresponded to no one crystallographic plane of the matrix lattice; the marking poles deviated from 5° to 11° from poles of the form {110}, and were displaced only a few degrees from (110) zones. Inasmuch as the new transition lattices produced as the result of the deformation are different for each alloy, it was thought at first that the habits of the markings might be the result of a cooperation between matrix lattice and transformed lattice. (Both matrix lattices are body-centered cubic.) Such a cooperative effect is thought to obtain in the formation of Widmanstätten figures, for it is well known that the matrix lattice alone does not determine the habit assumed by a segregate phase. On the other hand, it is not inconceivable that the dissimilarity in mark-ing habit might be due to differences in deformation characteristics of beta brass and beta bronze. Barrett and co-workers2 have shown that slip-line habits in pure iron are markedly different from those in high-silicon ferrite; and although it has been repeatedly demonstrated that plates of a segregate phase do not necessarily form on the slip planes of the matrix lattice, deformation characteristics may be more intimately allied with plate formation when a transformation is made to occur as a result of plastic deformation. However, there is the fact that the orienta-tion of markings in metastable beta copper-zinc is the same whether the markings be produced by quenching, deformation, or liquid-air cooling; likewise, quenching and deformation markings in metastable beta copper-tin are oriented in the same way with respect to the beta matrix.

Jan 1, 1938

By Ichinose M, Tsuru T, Gotoh K

Since 1980, the Department of Mining Engineering at Kyushu University, in co-operation with the Ikeshima Colliery, Matsushima Coal Mining Co. Ltd., has been conducting a research project into longwall gateroad designs applicable to deep and poor strata conditions. During this period, the economic environment has drastically changed the situation of the domestic coal mining industry. Conventionally, the retreat longwall method, with re-use of gateroad, has been employed as it achieves higher recovery. However, from the view point of production efficiency, this method is not suitable because it requires intensive work in side packing and roadway maintenance. Therefore an interpanel-pillar system, or a two-entry gateroad system, was adopted to identify the factors responsible for excessive vertical closure in longwall gateroads. Field measurements and non-linear finite element analyses were undertaken to confirm the performance of this system. Study results indicate that the stability of the gateroad employing the rib pillar system is comparable to that of the conventional system of re-using Gateroads.

Jan 1, 1992

By Phil N

A large number of experiments have been carried out by many workers on the recrystallization of deformed and subsequently annealed metals and alloys. Although observations on single crystals are of great importance in the study of the recrystallization textures of deformed and annealed metals, very little of this work deals with material in this form.Since, in deformed metals, the stress concentration is greatest at the grain boundaries and along the planes of slipping, it is to be expected that recrystallization will start in these regions. For example, in polycrystalline aluminium (1),:1: (2), copper (3), a-iron (4) and brass (5), (6), which had been deformed by cold-rolling, drawing, pressing or stretching and then annealed, the new grains first appeared in the boundaries of the original crystals, whilst in the case of cupronickel (7) and iron (8), recrystallization commenced along the slip planes of the deformed material. Deformed and annealed single crystals of aluminium (9) and cadmium (10) first start to recrystallize along slip planes and in deformation twins.The present work deals with the process of recrystallization of single crystals of lead after deformatjon by creep.Two factors enter into these experiments that were not met with in other work on this subject. Firstly, lead...

Jan 1, 1940