Abstract: In this paper, the authors discuss process planning for the lateral extrusion of a pipe with a lost core. In this process, maximum longitudinal length of the bulged part is restricted by the balance of the extrusion speed of the material and the lost core. In the free bulging condition, longitudinal length is limited to the pipe radius, because the extrusion speed of the core is slower than that of the pipe material when the longitudinal length of the bulged part is longer. The authors designed a two-stage forming process using the transit shape of a truncated cone to solve this problem. The dimensions of the truncated cone were estimated through trial-and-error using a commercial FEM simulator and considering the stretch effect for wrinkles of the pipe by deformation and traveling of the lost core. Finally, the authors conducted experiments to confirm the design’s validity. As a result, a longer longitudinal length of the bulged part than the pipe radius was successfully obtained.
Abstract: The purpose of this investigation is concentrated on brazing Inconel 600 (IN-600) using pure Cu and Cu-6Sn (wt%) filler foils in order to replace the current plate heat exchanger made by austenitic stainless steel. Both Cu and Cu-6Sn brazed joints consist of interfacial chromium carbides in the Cu/Ni-rich matrix. The application of Cu-6Sn filler foil to braze IN-600 alloy demonstrates average shear strengths of above 300 MPa, which is much better than those of Cu brazed ones (217 ~ 290 MPa). Ductile dimple fracture is observed from all fractographs of Cu-6Sn brazed joints after shear tests. Because the brazing temperature of Cu-6Sn filler is lower than pure Cu, dissolution of IN-600 substrate into the brazed joint is significantly decreased. Isothermal solidification of Cu-6Sn brazed joint becomes less prominent than that of Cu brazed one. Better Cu-6Sn brazed joint is obtained due to less isothermal solidification defects in the joint. The Cu-6Sn filler foil shows great potential in brazing the IN-600 plate heat exchanger for industrial application.
Abstract: This paper describes a production process for aluminum alloy sheet metal. Direct molten metal rolling, in other words strip casting process for aluminum alloy A3003 sheet was operated. Strip casting process is able to produce the metal sheet from molten metal directly. Thus this process has possibility of improving the productivity of sheet because of shortening operation of rolling. In this study, experimental device was designed for direct molten metal rolling. Aluminum alloy A3003 was chosen. A3003 is for aluminum can body, and the sheet required the high productivity. The effect of roll speed on the produced strip surface and strip thickness was investigated. Roll speed were 1, 2 and 3 m/min. It was possible to produce A3003 strip by direct rolling at the conditions of roll speed 3 m/min, pouring temperature 700 °C, solidification length 15 mm and nozzle exit width 15 mm. Obtained strip surface was flatten and had a metallic luster.
Abstract: This paper describes a vertical type twin roll strip casting process for producing aluminum alloy strip of ADC12, A3003 and A7075. Twin roll casting process is able to produce a strip from molten metal directly. Thus this process has a possibility to reduce total cost of sheet making comparing to conventional rolling process. Aluminum alloy ADC12 is a casting material that is used for die casting. A3003 is known as a wrought aluminum alloy for aluminum can body sheet. The A3003 sheet is generally produced by rolling, so it is effective for reducing a process cost to produce the strip by twin roll casting process. Aluminum alloy A7075 has high tensile strength, and it is known as a material for aerospace application. The sheet is manufactured in small quantities comparing to the other sheet aluminum alloy. It is supposed that the demand of high tensile strength aluminum sheet such as A7075 is going to increase for weight saving of structural material. In this study, twin roll casting experiment was performed to produce these three aluminum alloy strip in same experimental conditions. Castability, surface conditions and strip thickness were estimated. It was possible to cast these aluminum alloy strip.
Abstract: Currently, many industries are seeking to lower the use of lubricating fluids in machining processes without losing the quality of the workpieces, as an affordable alternative arises the possibility to applicate the minimal quantity of fluid technique (MQF). This study is focused on interpretation and evaluation of hardened SAE 4340 steel milling process using the MQF at different flow rates compared to conventional lubrication. With the implementation of a data acquisition system to measure the milling dynamic, it was possible to know all the present variations on the power rating during the process. After the tests, an appropriate statistical analysis of results was applied in order to better understand the effects of the MQF and correlate the output variables. Moreover, this project allows us to have an applicable vision of cutting process costs and study an important industrial material. As a result, the measurement and validation of the use of MQF in tangential and frontal milling process of hardened steels show good correlation with the dimension of carbide cutters wears and influence on the level of power rating, as it is detailed in this paper.
Abstract: Equal channel angular pressing, ECAP, is relatively a recent severe plastic deformation process which is carried out on materials to grain refine their structure. In this paper, the effect of addition of Mo to ZA22 on the maximum pressing force and the work consumed after the ECAP process is investigated and the obtained results are presented and discussed.
Abstract: Transient Liquid Phase (TLP) bonding was performed between Mg-AZ31 and Ti-6Al-4V alloys with various bonding temperatures using Cu coatings and Sn interlayers. The bonding parameters such as bonding pressure and bonding time were fixed at 1 MPa and 15 minutes respectively in order to study the effect of bonding temperature on the joint evolution. Bonds made at temperatures of 540, 560, 580 and 600 C showed good bond strength. The obtained bonds were investigated by Electron Probe Micro-analyzer EPMA and showed reaction layers and diffusion zones for all bonds made. The maximum joint shear strength of 78 MPa was obtained for bond made at 580 C. X-ray diffraction XRD and X-ray photoelectron spectroscopy XPS were taken for the fractured surfaces of bond made at 580 C. The analysis of the fractured surfaces found that the reaction layer contains Sn5Ti6 IMC in the titanium side and Mg2Cu IMC in the magnesium side where the fracture occurs at the diffusion zone in the mg side.
Abstract: Three different heat input combinations for the medium carbon alloy steels 5CrMoV are compared in terms of the heat affected zone of microstructures, hardness, and tensile properties. The microstructures in the heat affected zone are predominately ferrite and bainite, with grain size variation in different sub-zones and different heat input. Analyses of the micro-hardness profiles indicated that softening phenomenon occurs in the entire heat affected zone, and high heat input resulted in the greatest decrease in hardness. The results of the tensile tests reveal tensile properties of the heat affected zone deteriorate with the increase of heat input, and the region at temperatures near Ac1 is the weakest part of heat affected zone.
Abstract: Microstructures, Vickers depth profiles and low-temperature toughness of the tempered direct water quenched steels have been evaluated in the experiment. Martensite dominates the direct quenched specimen, and it is brittle at low-temperature toughness test. The toughness of direct quenched steel is improved when it is tempered at 500 °C for 1800 s. However, increasing the tempering temperature from 500 °C to 660 °C has little effect on low-temperature toughness of the steel. The application of offshore steel must avoid bainite formation. Tempering treatment is very effective to improve low-temperature toughness of the martensite dominated structure.