Advanced Materials Research Vols. 557-559

Abstract: The Ag behaviors of Ag-Al alloy that annealed in air atmosphere have been investigated. Over 600°C, the Ag-Al2O3 composite was prepared. But over 650°C, the size of Ag particles reduced notably. With the annealing time increasing, the amount of Ag particles reduced too. This phenomenon indicated temperature and annealing time play critical roles in annealing process. We attribute the loss of Ag to evaporation. According to discussion, the process of Ag evaporation is described in detail.

Abstract: For successful modeling of the solidification process, a reliable heat flux boundary condition is required. Many research works has contributed to understand the mechanism of heat transfer and to quantify the heat flux at the metal-mold interface. However, for ease of calculation, the metal-mold heat transfer is often assumed to be uniform and no spatial variation in the air gap formation among these researches. In this paper, a two-dimensional inverse conduction model is introduced. The proposed model can be used to calculate the heat flux with spatial variation. The accuracy and stability of the model has been investigated by a typical profile of heat flux simulating practical conditions of casting solidification. Meanwhile, the effects of various calculation parameters in the inverse algorithm have been also analyzed. The analyzed results show that the proposed inverse model is a feasible and effective tool for determination of the metal-mold interface heat flux.

Abstract: In consideration of the composition characteristics and quality requirements of L80-3Cr high chromium Steel, the reasonable alloying system, temperature system and key technologies in continuous casting process are employed in the development of a full-line operation of LD-LF-RH-Bloom continuous casting on steelmaking with semi-steel, which meets the economic production of steel has been realized. The industrial tests show that the average effective rate of Cr is 98.2% in smelting process, and Cr content in steel products is consistent. T[O] content of rolled products is ranged from 10×10-6 to 16×10-6 with an average content of 13.5×10-6. Various inclusions of the products are no more than 1.0 level. There is good surface quality and internal quality of rolled products.

Abstract: Deformation of shaft and turning process control mechanism were studied. When its clamping methods were different, its theoretical mechanics models were established. Based on probability theory, considering the randomness of cutting force, elastic modulus, its length and its diameter, its theoretical model was established to calculate its standard deviation of the roundness and typical parameters process systems were calculated. Moreover, its dynamic response finite element model was established, and the model was verified through comparison with the theoretical calculation results. The study provides the method and theoretical basis for the precision turning process planning.

Abstract: The research shows the characterization of mechanical properties in dissimilar steel welded unions: a structural steel ASTM A537 (I) overlap welded with an austenitic stainless steel ASTM A240 (304L) through semiautomatic electrical arc welding process protected by inert gas (GMAW); Argon is used as a protecting gas and austenitic stainless steel ASTM A240 (308L) as a supplier material. Samples were tested in not welded conditions so as to characterize the materials involved in the research, and they were also tested in welded conditions, not being submitted to pre and post welding Thermal Treatment (TT). Welded-based material samples were characterized through Optical Microscopy (OM) and Scanning Electron Microscopy (SEM), an inspection of Not Destructive Test (NDT) with penetrating liquids and ultrasound was also conducted. The following mechanical tests were completed, not only on the Base Metals (BM), on the Welding Join (WJ) as well: Vickers micro hardness profile, tension, and face bending test. Results showed a proper mechanical steel behavior, welded by GMAW procedure, under monotonic, in spite of the relatively high values of microhardness in the Heat Affected Zone (HAZ), specifically near the fusion line between weld and stainless steel.

Abstract: The purpose of this research is to study the effect of heat input on microstructure and hardness of SKD 61 hot work tool steel by using Gas Metal Arc Welding (GMAW) process. The specimens made of SKD 61 steel plates were austenized and oil-quenched to room temperature, then they were double tempered. Base on identical welding specification procedure (WPS), the specimens were automatically welded by GMAW machine. The consumable copper coated-solid wire electrode was used for surfacing in the GMAW process. The microstructures at the HAZ of specimens for all conditions were composed mainly of martensite with some retained austenite in the dendritic segregation pattern. With the higher heat input resulted in increasing in hardness, which resulted from transformation of retained austenite to martensite.

Abstract: Transformation behaviors and texture of Ni47Ti44Nb9 cold-rolled plates were studied by differential scanning calorimetry and X-ray diffraction test. R phase transformation does not occur in Ni₄₇Ti₄₄Nb₉ cold-rolled plate annealed at 350°C-750°C followed by quenching into the water. Martensite transformation temperature first increases and then decreases with increment of annealing temperature, and the maximum achieves at 700°C. The heat of reverse martensite transformation increases, while hardness decreases as annealing temperature increases. The major texture of cold-rolled plate is {332} and spread from {332} to {110}. When the annealing temperature is above 600°C, the major textures are {332} and {111} recrystallization texture in secondary cold-rolled plate.

Abstract: An experimental investigation of ac pulsed argon arc welding of the ZL105 alloy was carried out under the condition of existed the defects of the high temperature, the thermal deformation. The surface morphology, microstructure and temperature field of the surfacing layers were investigated. The results showed that the heat accumulation of squitter pulsed welding was less, and with smaller HAZ, crystal grains were thinner in the same conditions. Compared with argon arc welding, the energy of squitter pulse argon arc welding acted on the matrix was less but more centralized, the whole HAZ temperature raised slowly.

Abstract: This paper is based on the platform of the FEM software deform-3D, using numerical simulation technology, the FEM model of drilling No.45 steel is established; the equivalent stress and temperature of the workpiece through the dynamic simulation of the drilling process with indexable inserts can be obtained. Moreover, the cutting force, radial force of carbide and torque suffered by the two blades during the drilling process was analyzed and forecasted. What else, the wear of the blade was evaluated.

Abstract: To prevent the formation of the cracks in slide gate valve (SV) plate, theoretical analysis of the formation of the four types crack in it was carried out by finite element method, and its shape was improved on basis of its traditional structure. The results show that the analysis results match with the actual situations well. The new SV plate can prevent the formation of the cracks along its sliding direction effectively, and the pre-stress applying mode is simple.