Search Documents

By E. G. Noble

The potential for using heterotrophic microorganisms to solubilize manganese from low-grade domestic ores is being assessed at the Reno Research. center, U.S. Bureau of Mines. More than 90 pct of the manganese has been extracted from a variety of oxide ores in shake-flask tests using molasses as a source of .. nutrients for the microorganisms. It has also been demonstrated that high recoveries of manganese can be obtained from a domestic wad ore using column bioleaching. 'l'he isolation and identification of organisms responsible for manganese extraction is discussed, as are the mechanisms responsible for manganese solubilization.

Jan 1, 1991

By Robert H. Hsu

Palladium finely dispersed in a substrate of kieselguhr, Pd/k for short, has been successfully used for hydrogen storage, separation and pumping for a number of years at the Savannah River Site (SRS). Recently SRS has developed a new pd/k flow through bed (FTB) prototype for separating hydrogen from other gases and simultaneously storing the hydrogen on palladium. The FTB uses single-pass liquid nitrogen cooling during hydrogen absorption/separation/storage and electrical heating for desorption/unloading of hydrogen. Fourteen absorption-desorption or loading/unloading cycles using hydrogen have been conducted with the new FTB prototype. Test results show that all design performance objectives have been successfully achieved: recover 295% of hydrogen gas from feed gas, produce 99.9% hydrogen product gas and < 5% hydrogen in discharge gas. This paper will discuss characteristics of the palladium-coated kieselguhr or diatomaceous earth, design and operation of the FTB, and results of performance tests such as separation efficiency, hydrogen storage capacity and system heat transfer characteristics.

Jan 1, 2002

By Toshiro Kuji, Masakazu Fujita, Tetsuji Saito

"The magnetic properties of the magnetic materials were deeply dependent on the microstructures. In this study, the novel technique to produce the desired microstructures in a controlled manner was proposed. The technique consisted of the production of the amorphous alloys and the control of the crystallization process. The technique was applied to improve the magnetic properties of Nd-Fe-B permanent magnets. The microstructural control of the magnets exhibited the excellently high energy-products of higher than 430 kJm-1. The relationship between the magnetic properties and the microstructures of the Nd-Fe-B permanent magnets was discussed.IntroductionThe intrinsic properties of the materials are basically determined by the properties of the constituent elements or the compounds. However, it is often noticed the difference between the observed properties and the theoretical values expected from the intrinsic properties of the materials. This indicates that the observed properties of the materials are determined not only by the properties of the constituent elements. In other words, the observed properties of the materials are also strongly dependent on the morphology of materials. This means that the microstructural control may creates a great improvement of the properties of materials.In Nd-Fe-B permanent magnets, the superiority arises from the uniaxial intermetallic Nd2Fe14B compound which has a large saturation magnetization and a high anisotropy field [1,2]. The magnetic properties of the Nd-Fe-B permanent magnets are dependent on the microstructure, that is, the size, shape and degree of the crystallographic alignment of the Nd2Fe14B phase. Currently, the Nd-Fe-B permanent magnets have been produced by either sintering or melt-spinning [3,4]. In the sintered magnets, alignment of the Nd2Fe14B phase is achieved by the prior green compaction of the crushed ingot powders in an applied magnetic field [3]. In the melt-spinning approach, alignment of the Nd2Fe14B phase is achieved by hot deformation [5]. Amorphous melt-spun ribbons are comminuted and then are consolidated into bulk form by hot pressing before hot deformation. As-hot-pressed magnets have randomly oriented Nd2Fe1~ grains [6]. Subsequent die upsetting of as-hot-pressed magnets gives rise to the crystallographic alignment of the Nd2Fe14B phase."

Jan 1, 1998

By Veena Sahajwalla

The cupola furnace is a coke-fueled shaft furnace used as a primary melting unit in iron foundries. Control of chemical composition of the iron tapped from the cupola is a key factor in productivity and quality control. In an effort to develop a control model for the cupola, a fundamental approach based on physical and chemical principles has been taken to describe the melting process. The behavior of oxidation of the solid charge in the stack of the cupola has been studied. Sulfidation of the charge materials by sulfur-bearing components released to the furnace gases from the coke has been described. Carburization of metal droplets of iron and of steel in separate molten streams has been characterized. Finally, reactions with alloying elements in the hearth (well) of the furnace have been defined. These reactions have been described in a computer-implemented model developed to predict the composition of the iron tapped from the cupola. The model has utilized the thermodynamics and kinetics of the oxidation, sulfidation, and carburization reactions, including temperature and physical aspects, in the various zones of the melting unit. The model predictions have been compared favorably with operating results.

Jan 1, 1992

By Shaolong Chen, Carl-Gustav Berg, Hannu Mansikkaviita

Kumera Steam Dryer has been developed particularly for nonferrous metal concentrates with steam as heating source generated from waste heat boilers. Its unique structure enables the dryer to work at high capacity, up to 240 t/h, and high availability, over 95%. With half a century of engineering experience, and more than twenty industrial steam dryer installations worldwide during last 15 years, Kumera has demonstrated significant benefits of the steam drying technology in terms of energy efficiency and emission reduction to the end users. The dryer of this type can also be applied for other suitable mineral materials.

Jan 1, 2015

By F. M. Wang, J. P. Lin, G. Y. Tang, H. C. Zhou, Y. F. Liang, F. Ye

"Fe-6.5%Si alloy is a very excellent soft magnetic material compared with conventional Si steel (Si content ~ 3.5%), especially in high frequencies with reduced iron losses and noises. But it is hard to be fabricated due to its brittleness at room temperature. Dynamic electropulsing is applied to the cold rolled Fe-6.5%Si sheet during tensile deformation. Mechanical and microstructural properties are investigated with different electropulsing and strain rate. It is found that the yield stress decreases and the elongation increases dramatically with the application of dynamic electropulsing. It is indicated that the work hardening could be reduced with the dynamic electropulsing during deformation, which provides a promising way to fabricate this alloy sheet much easier.Introduction Fe-6.5%Si (weight percent, same as below) alloy has more excellent soft magnetic properties compared with conventional silicon steel (Si content ~ 3.5%), such as higher resistivity, higher permeability, near zero magnetostriction, etc. and exhibits much lower core losses and noises [1]. However, Fe-6.5%Si is very brittle at room temperature and hard to be fabricated in strip by conventional hot-cold rolling process [2]. This lack of low-temperature ductility has been generally attributed to structural ordering ofB2 and D03 phases [3]. Several methods have been developed to avoid its brittleness, such as chemical vapor deposition (CVD) [4], rapid quenching [5, 6], dipping and diffusion [7, 8], direct powder rolling (DPR) [9], etc. However, hot-cold rolling method is still of interest for industrial applications. In our previous work, this alloy can be cold rolled after certain thermomechanical process and heat treatment [10-13]. The cold rolled sheet exhibits some extent of ductility [11]. However, side cracks are common for the rolled sheet, it is very necessary to improve the ductility of this alloy by other technical applications."

Jan 1, 2012

By Ramana G. Reddy, M. R. Bogala

Transition metal silicides have good potential for converting waste heat into electrical energy at higher temperatures. Transition metal silicides are used as thermoelectric alloys at higher temperatures because of their low toxicity, high natural abundance, good transport properties, and better thermal stabilities. In this article, thermodynamic, and thermoelectric properties of promising metal silicides are reviewed, calculated, and compared for waste heat recovery application. Higher manganese silicide (Mn4Si7) was produced from easy one-step self-propagating high-temperature synthesis (SHS) procedure of arc-melting technique. Characterization of the alloy phases were done using X-ray diffraction (XRD). In this study, lattice constants, Vickers microindentation hardness, and thermoelectric (TE) properties (Seebeck coefficient, electrical conductivity, thermal conductivity, and figure of merit) of Mn4Si7 alloy were experimentally determined, and compared with the reported literature values.

Mar 1, 2017

By Katsuyoshi Kondoh

The synthesis processing of Mg2Si or Mg2Si/MgO at lower temperature from the elemental magnesium alloy powder/chips and Si or SiO2 powder mixture was established via the repeated plastic working (RPW) based on Powder Metallurgy (P/M) process. RPW is much effective on the mechanical breakage of MgO surface films, which prevent from the solid-state reaction between Mg and Si powder. The solid-state synthesized Mg2Si particle of 200nm-2JIm is extremely fine, compared to that via the conventional casting process, causing the coarse one of 50-100um. This is because of not coarsening during the solid-state synthesis of Mg2Si. By using in-situ forming process of Mg2Si via RPW and pre-heating before hot working such as extrusion and forging, the magnesium composite material with Mg2Si or Mg2Si/MgO dispersions was developed in employing Si or SiO2 particles, respectively. For example, when employing AZ31 chips as raw materials of the matrix, it has low density of 1.85g/cm) and extremely superior mechanical properties, such as tensile strength over 350MPa with 5-10% elongation and Young&apos;s modulus of 47-50GPa, to the conventional Mg-Al-Zn alloys. The Mg composite alloy wires and pipes were produced via the hot extrusion process in the manufacturing plant, and also showed excellent mechanical properties.

Jan 1, 2003

By John P. Hager

One possible approach for the recovery of mercury from acid plant blow-down sludge in smelters is the use of a vacuum retort reactor for the vaporization of the mercury with subsequent collection of metallic mercury in an attached condenser. An experimental study was undertaken to investigate the vaporization of mercury when present as a compound in the Hg-S-O and Hg-Se systems. A transpiration reactor was modified to operate under reduced pressure and with a continuous flow of inert sweep gas. A water-cooled cold finger was inserted into the exit end of the reactor to provide for the rapid quenching of the exit gases and the collection of the mercury. Rates of vaporization were measured at several temperatures for each compound and were generally found to be constant at a given temperature and reactor pressure. The results were used to determine the minimum operating temperature for 100% vaporization of the compound in 60 minutes. For Hg2SO4, HgSO4, and HgSO/2HgO the required temperatures. for a reactor pressure of 50 Torr. were determined to be 634°, 622°. and 603°C. respectively. For HgO, HgSe, and HgS the required temperatures were 557°. 451°. And 382°C. respectively. For HgS the rate of vaporization was also measured at a reactor pressure of 1 00 Torr. The rate of vaporization was found to be slower resulting in an increased vaporization temperature of 423°C. It was also determined that the mercury vapor present in the exit gas stream can back-react with the other gas species to a significant extent and can result in very little condensed metallic mercury. For the vaporization of both HgS and HgSe. the mercury vapor was found to have back-reacted to the extent that virtually none of the vaporized mercury was collected in metallic form. For the vaporization of Hg2S04? HgS04, and HgSO4*2HgO the amount of metallic mercury recovered varied from approximately 50% for HgS04*2HgO to approximately 10% for Hg2S04 and HgS04. Only for HgO was the recovered mercury in primarily elemental form. The application of the results to the operation of a vacuum retort and condenser system is discussed.

Jan 1, 2001

By Jin-yan TIE, Ke-xin JIAO, Qian Li, Hai-bin ZUO, Jian-Liang Zhang, Meng SHEN

This paper designs three factors such as temperature, pH, conductivity and three levels of orthogonal test. Temperature is a significant factor. However PH and conductivity are not significant through poor analysis. Further research is conducted on the temperature. Temperature stability is 50 . Suitable water velocity is 2.3m/s, which is calculated based on the largest part of the heat flux intensity and the corresponding water temperature should be controlled with 1.5. Meanwhile, water velocity increased has little effect on the heat transfer capabilities.

Jan 1, 2015

By Yukio Ishikawa

Sumitomo Metal Mining Co,. Ltd. (SMM) has been producing 22,000 t/y of electrolytic nickel at Niihama by nickel matte electrorefining process since 1970. Although the matte electrorefining is an established process and the productivity has been greatly improved in the last 20 years, SMM has intensively developed the chloride process for the nickel production since 1970&apos;s. The nickel and cobalt refining process involving solvent extraction and electrowinning from the chloride solution has been successfully developed for the treatment of the mixed sulphide in 1975. The first application of chlorine leach to the anode slime has been succeeded since 1986. Based on those technology, the matte chlorine leach electrowinning process (MCLE) has been developed as an alternation to the relatively old technology of matte electrorefining. The new process offers significant cost down and excellent quality of the product. In 1986, the feasibility of MCLE was confirmed by the test work using the integlated pilot plant. The innovation of the chlorine leach process has been undertaken by this work. The new refining process can be divided into three stages including chlorine leach stage, purification stage and electrowinning stage. More than 99 % of nickel was extracted in atmospheric chlorine leach. Although copper ion was used for electron carrier in the chlorine leach, the excess copper from the feed matte is bled off from the leach circuit by de copperizing electrolysis. The copper ion of the pregnant solution is fixed on nickel matte by the cementation reaction. The nickel matte containing copper is processed in the chlorine leach. In the purification circuit, cobalt, iron and other impurities were removed from the nickel chloride solution. The nickel chloride solution is then fed into the electrowinning cell. Based on the process established, the new plant with a capacity of 330 t/M electrolytic nickel was commissioned in order to obtain the engineering data for design of the full scale plant in 1989. The performance of the plant was fully satisfied and the new process demonstrated the potential application of modern process control.

Jan 1, 1992

By Alex Meystel, Diran Apelian

"In this paper, an outline is given for a theory of intelligent control (IC) of manufacturing processes (MP) based upon what all of them have in common: all MP's can be represented as distributed networks of sequential/parallel elementary ""lumped"" models; all elementary models are organized by definite input-output conditions, and by the set of constraints; all elementary models incorporate not only well defined physical knowledge, but also assumed physical knowledge, expert knowledge, expected knowledge to be obtained during the process from sensors, etc. This creates a hierarchy of elementary controllers coordinated by local coordinators of different levels up to a global coordinator. The latter verifies the adequacy of MP by using a holistic image of the process: depictogram. The structure of knowledge based controller is introduced, and the analytical/linguistic tools of control are presented. The concept entails a number of perspectives which are discussed in the conclusions.1. IntroductionIt is becoming increasingly clear to those of us in Engineering and Technology oriented fields that the so called ""service industries"" do not create wealth. Moreover, it is now accepted that manufacturing is the key to the creation of wealth from a socio-economic point of view. This appreciation of the importance of manufacturing is reflected by the transformations we are seeing in our factories, as well as the changes in both curricula and research activities of our universities. Though we find these changes to be in the right direction, there is yet much more to be done to advance the frontiers of manufacturing and materials processing as we approach the third rnillenium."

Jan 1, 1988

By Dan Wang, Yuanbo Zhang, Guihong Han, Guanghui Li, Tao Jiang, Yanfang Huang

"Hematite concentrates are characterized by bad high-temperature reactivity and poor balling index, which restrict their large-scale application in the production of oxidized pellets. An organic additive, namely MHA, was authorized and used as binder recently in China. Compared with bentonite, the effects of MHA on compressive strength of hematite pellets at various firing conditions were investigated in this study. Experimental results showed the compressive strengths of preheated pellets with different binders were increased with increasing the preheating temperature and time. The compressive strength of preheated pellets with MHA binder was lower than that of pellets with bentonite, which can be ascribed to the high porosity of pellets with MHA binder. However, the compressive strength of roasted pellets with MHA binder was higher than that of pellets with bentonite. The compressive strength of finished pellets balled with MHA binder 1.0 wt% could meet the operation requirements of grate-kiln process.IntroductionHematite concentrates are characterized by bad high-temperature reactivity and poor balling index, which can lead to the appearance of those problems with increasing the energy consumption, shortening the useful life of equipment, and finally increasing the operation cost of oxidized pellets plants [1-2]. Some investigations have been conducted based on improving the pelletizing technique of hematite concentrates, such as pretreatment of raw materials [3-7], optimization of ore proportioning [8], addition of solid fuels [9-16], and so on. Employing high pressure grinding roller for the treatment of hematite concentrates revealed that the mechanical strength of wet green pellets could be improved. However, the mechanical strength of fired pellets was not improved obviously [7]. Huang, et al., pointed out that the preheating and roasting temperature may be decreased and the compressive strength of fired pellets could be increased by blending a certain proportion of magnetite concentrates with hematite [8]. Nevertheless, there are a variety of magnetite ores different in physical and chemical properties in China, resulting in the instability operation [17]."

Jan 1, 2012

By A. K. Kyllo, N. B. Gray, B. N. McCurry

"Dynamic control of the formation of a solidified layer between a pipe wall and a flowing melt enables the flow rate to be adjusted in real time. This solidified layer can be generated by using a coolant on the outside of the pipe wall to remove the required heat. The coolant, and hence the solidified layer, can be controlled remotely. The dynamic behaviour of the solidified layer was investigated by both physical experiments and mathematical modelling. The mathematical model has been developed using a finite difference technique to describe conduction through the pipe wall and solidified layer. Results from the model were consistent with previous steadystate experimental results using molten lead. Experiments are currently being carried out using molten tin in a recirculating circuit with a cooling system that is instrumented for accurate computer control to validate the model. The circuit is designed for flowrates of up to 24 kg/s (86 tph) of molten tin. Steady-state and dynamic predictions were made for the current rig.Industrial SignificanceThe current method of choice for tapping slags, metals and mattes from many metallurgical furnaces is using an oxygen lance to open the taphole and using a clay plug to close it. There are, however, some significant drawbacks in this method. The heat generated by the oxygen lance erodes the refractory lining of the taphole, as well as the clay plug, and the furnace products themselves corrode the taphole. Using an oxygen lance is also a significant safety hazard to the operators as they must work in close proximity to the furnace and be subjected to a shower of sparks while opening the taphole. Also, the flowrate of material through the taphole cannot be controlled online as the diameter of the opening cannot be varied easily. This feature means that the level of product in a furnace cannot be kept constant."

Jan 1, 1999

By E. Açma

Sivas-Divrigi flotation plant has a capacity of 90,000 tpy. Beneficiation of the tailings of iron ore magnetic separator seems to be attractive, because of its Cu, Co, and Ni contents. In the experimental work, sulfidic flotation concentrate is produced from these tailings. A roasting-leaching-H2S precipitation procedure is used to treat this concentrate, containing 0.55% Cu, 0.51% Co, 0.74% Ni, and 0.027% Zn. Sulfatizing roasting is carried out in a rotary furnace at 690°C. Roasted product is leached with 10 gpl HzSOl at 70°C and 30% pulp density. For the precipitation of desired metal, H2S is bubbled through the concentrated solution of repeated leaching, under controlled temperature and pH. Final metal recoveries of 91% Cu, 91% Co, and 50% Ni, and 92% Zn are attained. Roasting gases with their 13% SO2 content are suitable for H2SO4 production and the leach residues can be integrated with the iron ore processing plant as they contain 57.4% Fe and very low non-ferrous metals.

Jan 1, 1993

By I. Gaballah

The kinetics of oxychlorination of pure CI-2O3 with C12+02 gas mixtures is studied by ThermoGravimetric Analysis (TGA) in non and isothermal conditions up to 1000 °C. The reaction of Cr2O3 with C12+O2 chlorination gas mixtures starts at about 550 °C and the reaction product is CrO2Cl2. The oxychlorination rate of Cr2O3 is almost proportional to the chlorine partial pressure and to the fourth root of the oxygen partial pressure in the chlorinating gas mixtures. At 800 °C, the maximum chlorination rate is obtained using a gas mixture having a C12/O2 ratio equal to 4. The apparent activation energy of the oxychlorination reaction of Cr2O3 is 87 and 46 kJ/mol at temperatures lower and higher than 650 °C, respectively. By varying the chlorine and the oxygen partial pressures of the oxychlorinating gas mixtures at temperatures higher than 550 °C, it is possible to extract selectively the chromium chlorinated compounds from the chromium bearing materials. a. Laboratoire Environnemem et Minéralurgie, BP 40, 54501 Vandceuvre, France, b. École Nationale Supérieure de Géologie, Rue du Doyen Marcel Rouhault, 54501 Vandoeuvre Cedex, France, c. Centre National de la Recherche Scientifique, 3 rue Michel - Ange, 75794 Paris Cedex, France, d. Insritut National Polytechnigne do Lorraine, Rue de la Font de Haye. 54501 Vandceuvre Cedex, France.

Jan 1, 1997

By Laurent Cohen

Since the 1970s, Solvent Extraction (SX) in hydrometallurgical processes has been a key enabling technology in the production of high-purity metals. Examples include copper, rare earth oxides, uranium, cobalt and nickel. Notwithstanding incremental improvements in extractant formulations, few breakthroughs can be recounted in this industry outside of the initial amine-, oxime- or phosphine-based reagent chemistries. However, the advent of lithium-ion batteries and their stringent requirements for critical materials (lithium, cobalt and nickel) offer new challenges and opportunities for SX. Solvay recently introduced a new extractant for lithium, CYANEX® 936, and developed unique modeling software capabilities in cobalt/nickel separation using CYANEX® 272, zinc SX using DEHPA® and rare earth separations using CYANEX® 572. This paper discusses trends in SX and provides insight on processing of critical materials essential to energy sources. It also summarizes the technical and economic benefits based on extractant selection and advances in modeling.

By Patrik Yrjas, Daniel Lindberg, Emil Vainio

Recovery of trace elements from different industrial waste streams is important in realizing the goals of the circular economy. Ash streams from waste combustion can contain high levels of both toxic and valuable trace elements. These elements can be separated during the combustion process based on volatilization and condensation, as well as being separated in post-combustion processes, through thermal or leaching treatment. In this study, an overview is given of the thermal methods for recovery of valuable elements from ash fractions derived from waste incineration. In addition, a case study is presented of the behaviour of ash-forming elements in combustion of MSW and demolition wood, with special focus on the elements Co, Cu, and Sb. In conclusion, it is shown that thermodynamic modeling of high temperature processes can be a useful tool to predict ash behavior both during combustion and in the post combustion treatment of the ash.

Mar 1, 2018

By Vinod K. Sikka, René Cooper

"Cohoes, New York 12047 Intermetallics are an attractive class of advanced materials. The aluminide intermetallics offer advantages including: (1) lower density, (2) oxidation resistance, (3) carburization resistance, and (4) interesting mechanical properties because of their ordered crystal structure. Even though the attractive properties of the aluminides and other intermetallics have been known for nearly four decades, their practical applications have not been developed for two reasons: (1) the poor ductility (in some cases, both ambient and high temperatures) and (2) the lack of processability into meaningful components. Recent advances such as ductilization of Ni3Al by small additions of boron and the knowledge that environmental effects are the major cause of poor ductility in Fe3Al and FeAl systems have brought the intelmetallics into the forefront of research and their commercial applications. This paper has described a method for melting Ni3AI-based alloys that successfully utilize the exotherrn for the formation of NiAl from the elemental materials. The reaction-synthesis method has also been utilized for the production of NiAI and NiAI-based alloy powders from the elemental powders. The reaction-synthesized powders of NiAI and NiAI-based alloys were consolidated by hot extrusion and evaluated for tensile properties over a temperature range from room temperature to 1050ºC. The powder-processing conditions have been found to have more influence on the ductile-to-brittle transition temperature of NiAI than the powder-production method.IntroductionIntermetallics are an attractive class of advanced materials [1-11]. The alum in ide interrnetallics offer advantages including: (1) lower density, (2) oxidation resistance, (3) carburization resistance, and (4) interesting mechanical properties because of their ordered crystal structure. Even though the attractive properties of the aluminides and other interrnetallics have been known for nearly four decades, their practical applications have not been developed for two reasons: (I) the poor ductility (in some cases, both ambient and high temperatures) and (2) the lack of processability into meaningful components. Recent advances such as ductilization of Ni3Al by small additions of boron and the knowledge that environmental effects are the major cause of poor ductility in Fe3Al and FeAl systems have brought the intermetallics into the forefront of research and their commercial applications. The paper will briefly review the processing techniques being pursued for the commercial applications of Ni3Al-based intermetallics. The major emphasis of the paper will deal with synthesis of Ni3Al and NiAI intelmetallics."

Jan 1, 1994

By B. Q. Li, R. A. Mirshams

"A numerical algorithm is described for the simultaneous prediction of the thermomechanical behavior of the materials and microstructure evolption during metal forging. The numerical development is based on the finite element solution of the thermoviscoplastic deformation of metals coupled with the internal state variable model describing the microstructure evolution involving work hardening, recovery, recrystallization and grain size distribution. The finite element code for rigid viscoplastic deformation is developed based on the modification of the existing code for the thermal and fluid flow calculations. The code is tested against and compares well with the results reported in literature. The procedures for the integration of the · rnicrostructure model into the macro finite element model are described. Results are presented showing the characteristics of materials dynamics and mechanical deformation during simple metal forging processes.IntroductionIn industrial deformation processes such as hot rolling and forging, the workpiece undergoes both macroscopic plastic deformations and microstructural evolution. A computer model that allows to predict both materials dynamics and macroscopic deformation is obviously more useful for both fundamental understanding and deformation process optimization. For some industrial applications, especially those involving novel, light and high strength materials, such an integrated model is critical in that both materials and thermomechanical 'behavior during forging must be carefully controlled to obtain the products that meet the desired strength requirement [I]."

Jan 1, 2000