Abstract: In this paper, the following topics are discussed:the solidification structure and phase constituents in argoin atomized powder particles and the chemical analyses on particle surfaces; the microstructures and phase constituents of the alloy after hot isostatic pressing (HIP), the nature of the previous powder particle boundary (PPB) carbides and the mechanism of their formation; the improvement of microstructure in the HIPed blank with hot extrusion and the overall enhancement of high temperature tensile, stress rupture and low cycle fatigue properties with a modified final heat treatment.
Abstract: Mechanism of explosive sintering of two kings of high speed steel powder with remarkable difference in frain size is studied, In the course of sintering "grain effect" is found apparently. That is, for the HPS powder with the same composition,small grain is prior to melting than the large. The melting process takes place in peak pin.Melting bed will gradually build along the grain surface with the increase of shoce energy,there by resulting in intensifying fluid motion.accelerating grain melting.Finally grains bind each other,sinter-ing occurs.
Abstract: Recrystallization behaviors of a P/M nickel-base superalloy with high volume percent of γ' phase have been studied. It is shown that above the dissolution tempreature of γ' phase a mechanism for the nucleation is the grain boundary migration induced by strain, below this tempreature, mechanism is the coarseing of the subgrain. Complete decomposition of the γ' phase can occur with subsequent reprecipitation at the recrystallizing interfaces. The migration activation energy of recrystallizing interfaces of γ' phase was 635kJ/mol.
Abstract: A superalloy, Waspaloy, was selected as a typical blade alloy for the advanced flue gas turbine. Two different heat treatments which resulted in the different microstructure and mechanical properties were investigated and compared. However, the blades with these two heat treatments have been successfully performing for more than one year. A detailed discussion was given in this paper.
Abstract: Magnesium effect on mechanical properties of GH169 superalloy especially at high temperature service condition has been studied in a wide range. A proper content of Mg should be controlled to meet a new requirement, which is important for developing high quality GH169 (INCONEL718).
Abstract: The investigation about influence of cobalt on properties of superhard W-Mo and Mo system high speed steel (HSS) containing 1% V had observed that the secondary hardness rised with the increasing of cobalt, and the strength and toughness could be increased in the range of 3%~5% Co. When cobalt content arrived to 8%, the brittleness would be appeared. A new type of superhard high speed steel, Co3N, with low cobalt content and the same hardness,red-hardness, strength, toughness and erindability of M42, was developed.
Abstract: The effects of chemical composition and heat-treatment on the impact toughness of a new type of micro-calcium steel with high-hardness (HRC> 58) and high-toughness (ak> 40J/cm2) have been investigated. The results show that the micro-calcium play an important role in the improving of impact toughness of quened-tempered steels. The impact toughness of steels were also controlled by the content of chromium and the ratio of copper/silicon in steels.
Abstract: The state of cosegregation of P and Ce at ferrite grain boundaries in iron has been studied using the conbination with XPS and computer modelling. The results indicate that the concentration of P is less, the P atoms at grain boundaries are solid solution state and the influnce of Ce on the chemical state of P at grain boundaries is very small.As the concentration of P at grain boundries is rather high,Ce may change the chemical state of P.The computer modelling shows that the chemical state of P at grain boundaries depends on its segregated structure.
Abstract: Using scanning election microscope equipped with X-ray energy dispersion spectrometer and optical microscope the phenomena of diffusion induced grainboundary migration (DIGM) caused by Ag diffusing along the grain boundaries of Cu in Ag(film)/Cu (bulk) diffusion couple annealed at 400℃,480℃ and 580℃ with various times was studied. Based on the characteristics of the migrated boundaries, the diffusion coefficient of Ag in the migrated grain boundary was calculated by an appropriate solution of the diffusion equation for the migrated boundary.
Abstract: With hot press simulator the microstructural changes of 15MnV steel in hot deformation and subsequent cooling was investigated. A methematical model for evoluation the microstructural changes is obtained. The model consists:austenite recrystallization kinetics, recrystallizied grain size, grain coasenning after recrystallization in single pass and multiple passes deformation under isothermal and continous cooling conditions, and the ferrite transformed from hot deformed austinite. Good agreement was obtained between the results predicted and measured.
Abstract: The influence of different heat treatment on thermal shock resistance of 86CrMoV7 steel used as cold working rolls, has been investigated by using friction thermal shock method. The results show that under the same quenching temperature, the higher the quenching temperure, the worse the crack resistance and the higher the tempering temperature, the better the crack resistance.
Abstract: Periodic banding phenomena in carbon manganese steels with three different composition levels of Mn and four different levels of carbon have been studied by SEM and microprobe analysis. The experimental results showed that:In all the alloys studied, banding formed after hot rolling of the ingot, but the severity of banding varied with composition; Formation of banding is related to microsegregation of manganese in the ingot and hot band; The severity of banding can be reduced by (a) properly adjusting carbon and manganese and (b) by the formation of transformed products breaking through the ferritic bands.
Abstract: A785MPa-grade weldable HSLA steel (HQ80C) with Cr, Ni, Mo, V, Ti, and B has been experimentally studied to determine quantitative relationships between properties (strength and toughness) and microstructures. It has been found that the ductile-brittle transition temperature (50%FATT) varies linearly with the mean intercept of martensitic packets. An empiric equation has been established to predict the yield strength of the as quenched and tempered steel; the relative deviation of the predicted yield strength values from the experimental ones are all less than 3% when the steel was tempred at 500 to 700℃.
Abstract: The temperature of austenite grain coarsening and recrystallization parameters in steels containing 0.04%-0.16% Ti have been investigated.Experimental results show that after heating at 950-1 200℃,austenite grain size in 0.04% Ti-steel was the finest, and the temperature of grain coarsening was above 1 150℃.The quantitative relationship between the critical reduction for austenite recrystallization εc and initinal austenite grain size Do at rolling temperature T has been obtained
Abstract: This paper is to investigate the mechanical properties and deformation mechanisms at low temperatures of Ti-5AI-2Mo-3Zr alloy. The results showed that quenched samples kept theit high plasticity until -75℃.while the tempered samples were with very low elongation.This means that alloying zirconium is beneficial to low temperature plasticity only when it is at solution state, but not at precipitation state.The deformation mechanism changed from slip to twin during testing temperature lowering.TEM observation showed a special morphology of double "triple twins",may indicating that the crystals rotated from each other a rather large angle during low temperature deformation.
Abstract: Based on the wanger thermodynamic model, a computer program capable of calculating the equilibrium and paraequilibrium temperatures of austenite-ferrite transformation in multicomponent alloy steels with additions of Mn, Si, Ni, Cr, Mo, Cu, V, Nb, W and Co (total alloy < 7%) has been developed. The temperatures of austenite-ferrite transformation for a large amount of low alloy steels were calculated by the program. It is demonstrated that the predicted values compared favorable with the observed values.
Abstract: A SHS-Pressing method was developed to form dense TiC/Ni functionally gradient material.The mechanisms of combustion synthesis-densification in Ti-C-Ni systems were studied.It is proposed that carbon is dissolved into Ti-Ni melt;TiC is presipitated from the melt;The dense TiC/Ni FGM is formed by liquid phase sintering under pressure.The grain size of TiC decreases with increasing content of Ni because of reduction of combustion temperature. Grain shape of TiC varies with the content of Ni.The morphology of TiC grains changes from polyhedra to spherical shape by accommodation process when the quantity of Ni melt increases.
Abstract: The properties of the Wiegand-type sharp voltage pulses and detectment of the small pressures,the static magnetic field and the displacement have been reaserched for the highly magnetostrictive Fe-based amorphous ribbons and wires,low or zero magnetostrictive Co-based ribbons and wires used for sensor's elements.The Fe-based amorphous ribbon-woud cores have good linearity and very high sensitivity.The sensitivity to pressure is high as 2.7V/N.Cobaese amorphous ribbons have good linearly and sensitivity (14mV/A·m-1).The sensitivity to displacement is 30mV/mm,and the linear range is about 100mm
Abstract: Sm2(Fe,M)17Ny compound powder has been made by the hydrogen treatment and nitrogen absorption treatment. The effects of Sm content and the additions of Co,Cr,V,Zr,Si and Ga on magnetic properties of Sm2(Fe1-xMx)17Ny, compound powder have been studied.The coercivity of Sm2(Fe0.987Ga0.017)17Ny powder is 2 000kA/m
Abstract: The effects of the alloy composition,homogenization treatment and the dehydrogenation process in HDD treatment on the magnetic properties of NdFeB powders and bonded magnets are studied. The experimental results show that the NdFeB powders made by HDD process are stable with respect to time and temperature
Abstract: High temperture corrosion tests in 75%Na2SO4-25%NaCl molten salt have been conducted on GH864 superalloy specimens plasma sprayed with great wall No.1 and X-40 coatings. After the corrosion tests,each sample was examined by OM, SEMand EMPA.It was found that X-40 coating was severely corroded by the molten salt due to cracking and spalling, whereas the Great Wall No.1 exhibited superior corrosion resistance.
Abstract: Characterization of Bw/Ti composite fiber stress-strain response was explored.Both of experimental and composite consists of elastic deformation of fiber and elastic-plastic deformation of matrix. In addition,under the condition of firmly coherent interface between fiber and matrix as well as less than 50% volume fraction of matrix compc-nent,the composite fiber performs a high strength,high modulus and low plasticity behavior which means ensurement of excellant properties for fiber and limitation of plastic potentiality for matrix. Finally,comparison between experimental and theoretical results was made and the agreement of both was satisfactory.
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
