Abstract: The reasonableness and limitations of the failure criterion for rock in terms of stress are described and it is emphasized that development of failure criterion in terms of strain has been of great significance on rock engineering design.According to the test data on rock specimen, critical strain curves are presented as rock failure criterion.. Finally, the general approach of direct strain analysis to the stability of underground excavation is introduced. Obviously, combination of the two kinds of rock failure criterion would be one of the significant characteristics on rock strength theories.
Abstract: This paper shows the research results about quality of the austenitic stainless steel(Ti) billet produced by the special steel billet caster in China. A series of measurements including macrograph, inclusion,segregation of composition and billet surface and property of final rolled steel products confirm that the continous casting process gives satisfaction to the quality of the products.
Abstract: One of the recent stereological techniques, i.e., the inflection point count method and corresponding fundamental stereological relationship have been described and derived by means of the set theory, with their various pote ntial applications in materials science also being discussed.
Abstract: The transition-metals must be used in order to improve the strength of the welding places when hard metal and alloy tool steel are bonded by diffusion. This paper studies the technology which influences the welding strength when Co and Ni are used as the transition-metale. The catalogue of transition-metals, thickness and the thermal expansion coefficient which influence the strength of the bonded places are studied as well.
Abstract: The CCT curve of 3CrMnMoVS steel has been mersured, and it is used to analyse the optical and electron-microstructure of the steel, which was continuouslly cooled at a moderate cooling rate of 200-1000℃/h. The marphology observation and electron diffraction analysis show that under the cooling rate greater than 0.72℃/s the microstructure mainly consists of lath matensite, in contrast after air cooling the morphology indicates the product of intermediate temperature, e.g. the fine mixed structure of Bg+Bu+B1 with a few dispersive VC in it.
Abstract: The room temperature ductility of Fe3Al intermetallic compound has been improved by Cr addition and rapid solidificaton processing. The experimental results show that RSP decrease the grain size and the degree of order and 2%Cr addition increases the room temperature ductility from 2% to 5.6%, which may be associated with the increase of cleavage stringth.
Abstract: This paper introduces a new way that can measure the speed of wedge cross rolling and rolling radium with Apple-Ⅱ computer. It says, the precision of measure can be increased if the precision of equipment is enough. The way is proved to be excellent by measuring the rotating speed and rolling radium of some semifinished spare part as an example.
Abstract: The algorithm principles, features of the software package MOD and comparative study of the algorithim are presented. At the end of the algorithm perfermance curves and the evalutive results, and the design examples for mechanical engineering are given.
Abstract: For a VVVF Inverter--fed vector control system of inductino motor, not only realized complet decoupling between the torque and flux curremt vector of induction motor, but also ensured the maxium and constant torque control during the dynamic case if it is regulated by current and speed double control loops. In this paper, the structure of current and speed double loops for SPWM inverter--fed induction motor's vector control system is investigated. For ensurring the flux orientation in case of motor's parameters being changed, flux control loop is realized through calculating magnetic energy of motor. The modulation frequency of SPWM converter is calculated through simulation of several main harmonic components.
Abstract: The electromagnetic interference shielding effectiveness of CF/ varnish and CF/epoxy prepreg are determinated. The experimental results show. (1) The compactness of CF in the coating has an important influence on shielding effectiveness, (2) The CF/epoxy prepreg is a prospective shielding material, (3) The surface reflection is main mechanism of electromgnetic shielding by CF.
Abstract: The decomposition of the hydride in cold-roiled nickel is investigated by doppler broadening and X-ray method. The experimental results show that when cold-rolled nickel is charged with hydrogen in a 0.5mol/l H2SO4+ 250mg/l As2O3 solution, a fcc β phase (hydride) is formed. It is unstable and decomposes immeditely after the interuption of the charging process. Hydrogen is not sensitive for positron, but if low hydrogen concentration is introduced into the cold-rolled nickel whinin short charging time. PAT can detect the process of the hydride decomposition. Its results are consistent with the outcome using X-ray method. A mechanism of interaction between hydrogen and vacancy has been suggested, hydrogen atoms can be regarded as the centres for vacancy agglomeration, resulting in the formation of vacancy clusters. It may explain the variation of S-parameter with ageing time when the nickel hydrides decompose.
Abstract: The behaviour of boron segregation on moving grain boundaries during recrj'stallization after high temperature deformation was investigated in a Fe-3% Si alloy by means of boron particle track autoradiography (PTA). Such kind of segregation was observed after 20% deformation at 1000℃, and disappeared as the grain boundaries stopped. Based on the above results a mechanism of dislocation relaxation on grain boundaries is proposed for the segregation on movig boundaries.
Abstract: Hydrogen induced austenite structure transformation and martensite transformation in 304L stainless steel during hydrogen charging and aging were studied by X-ray diffraction. The results showed that hydrogen charging could induce austenite lattice expansion and martensite transformation.α' phase and ε phase appeared in the same time, and they did not disappear after aging at room temperature.
Abstract: A new phase, i, e. hexagonal cobalt carbide with a=0.268nm and c = 0.433nm was formed by carbon ion implantation. The only phase formed for the three ferromagnetic metals, i. e. bcc. Fe, hcp. Co and fcc. Ni after carbon ion implantation was the corresponding hexagonal carbide respectively. Structural simplicity was concluded to be the dominant characteristic of phase formation by ion implantation comparing to the conventional thermal process. Amorphous alloy may also be readily formed in ion beam process. The conclusions may be used to direct experiments in general and expected other new phase to be found.
Abstract: This papar presented a study of low temperature chemical vapour deposition of TiN in TiCl4-NH3-H2 system. TiN was obtained at the temperature of 500℃. Its hardness HV0.1 = 17.67kN/mm2, and lattice constant a=0.4234nm.The Surface reaction activation energy of TiN was 67.3kJ /mol. Decomposition of TiNCl, from which TiN was produced, was also studied. The activation energy of this reaction was 131kJ/mol.
Abstract: A new kind of surface for modelling-BRB spline surface-is introduced here. Comparing with both Bezier surface an'd B-spline surface, BRB spline surface can keep basic advantages of modelling and has a high composite target of modelling capability. The definition and geometric properties are given for BRB spline surface. Some adjacent problems between BRB spline surfaces are discussed.
Abstract: Expanded the elemental matrix of a uniform Timoshenko beam by J. Thomas into the matrix of a variable cross-section Timoshenko beam. By comparing with the simple beam, the present results show that:the influence of the wider end of beam on natural frequency arc larger.
Abstract: The amplification of optical phonons in interface system under the intense laser is first presented. It is well known that the vibration amplitude of the interfacial modes appear damping form. The results show that when the wave vector with parallel to the interface exceeds the damping constant and the field strength exceeds a certain threshold, the population of interfacial optical phonons grows with time. The threshold of field strength and the power of laser required in experiment are approximately estimated.
Monthly, started in 1955 Supervising institution：Ministry of Education Sponsoring Institution：University of Science and Technology Beijing Editorial office：Editorial Department of Chinese Journal of Engineering Publisher：Science Press Chairperson：Ren-shu Yang Editor-in-Chief：Ai-xiang Wu ISSN 2095-9389CN 2095-9389
