Advanced Materials Research Vols. 690-693

Abstract: Welded pipe and special pipe get more and more applications; however, the difficulty of pass design method limits welded pipe manufacture. The paper discusses welded pipe roll pass design method based on CATIA, and roll CAD/CAPP computer aided design system based on AutoCAD, and gives roll virtual design methods which use roll CATIA, CAD/CAPP system.

Abstract: The propeller shaft of rear-wheel drive vehicle is an axis which transfers power from an engine to rear-wheel through differential gear box. In this study, we studied the properties of friction welding required to produce the aluminum propeller shaft of lightweight rear-wheel-drive vehicle. We studied welding property to apply Al 7075-T6 aluminum yoke to automobile connects driving shaft and differential gear box. Here, solid phase friction welding method was used. In friction welding process, the principal parameter is spindle speed, up-set pressure and up-set time. We analyzed variable characteristics of friction welding strength according to the change of the spindle rate and up-set pressure. Friction welding strength was analyzed with ultimate tensile strength test with universal testing machine (UTM). The Al 7075-T6 was used as the round bar of the diameter of 25mm. The ultimate tensile strength was 552.3 MPa. It is 94% of ultimate tensile strength of pure Al 7075-T6 material. The main parameters of characteristics are discussed in detail based on analysis of the main effects plot and multi-vari chart. Finally, the core factors to get the maximum effect of friction welding investigated.

Abstract: The variations of temperature profile and residual stress distribution in the single V butt welds were studied in this work. The thermal elastic-plastic model of ANSYS finite element analysis software is employed in this study to simulate the melting and solidification processes of two clamped nickel alloy 690 plates with different welding parameters; i.e. the welding speed and the number of weld passes. The temperature dependent material properties are used. The effects of these welding parameters on the residual stresses around the weld are investigated. Numerical results reveal that these welding parameters may affect the distribution of residual stresses significantly.

Abstract: Combining with welding and numerical control technology, welding automation technology has brought the new development for welding equipment industry. This paper mainly aimed at automatic welding process needs for intersecting line of T-type tube, developed a practical automatic welding machine of T-type tube intersecting line, used the PCL893 movement control card as the core control unit, realized whole rotary feed of welding head and front and rear feed of the torch, etc. Integrating with mechanical cam and digital cam, the work achieved space fitting of saddle-shaped weld track so as to realize automatic welding process, imitate the manual welding process of space curve, reduce labor intensity, improve the efficiency of welding and quality.

Abstract: Residual stress affect the lifetime of weldments directly. Temperature Generated from the welding process is the major reason that influences the microstructure and mechanical properties of the metal weldments. Therefore it is necessary to simulate the temperature field for optimizing the structure of weldments. In this work the three-dimension finite element analysis software SYSWELS was used to simulate T-type tube, and carried on a detailed analysis of temperature field and residual stress in cool process of weld.

Abstract: Joining of copper tubes using Ag-Cu filler has been carried out by vacuum brazing technology. The microstructure and mechanical property of brazed joints were studied by means of metallography, optical microscope (OM) and universal tensile test machine. Experimental results show that failure occurs in the base metal and the tensile strength can reach 179 MPa. The optimal vacuum brazing parameters are: brazing temperature 820 °C, vacuum level 10^-3Pa and holding time 5 min.

Abstract: Influence of the fluctuation frequency on stress corrosion cracking (SCC) behavior of X70 pipeline steel welding joint was studied in the cathode potential under nearly neutral medium by fluctuant slow strain rate test (F-SSRT). SCC sensitive parts occurs in overheated zone of X70 pipeline steel welding joint under cathode potential nearly neutral medium. SCC crack can be produced from the material surface micro holes and expanding their range up the main stress plane extension, when the load fluctuation frequency increases to a certain degree, SCC crack propagate along 45° maximum shear stress plane.

Abstract: Recently, the fuel oil of diesel engines of marine ships is being changed to heavy oil of low quality as the oil price is getting higher and higher. Therefore, the wear and corrosion in all parts of the engine, such as cylinder liner, piston crown, and spindle and seat ring of exhaust valves has predominantly increased. Thus, the repair welding of the piston crown is a unique method to prolong its life in a economical point of view. In this case, filler metals with a high corrosion and wear resistance are mainly being used for repair welding. However, the piston crown on the ships job site is often actually being welded with mild filler metals. Therefore, in this study, mild filler metals, such as E4301, E431316, and E4316, were welded to the SS401 steel as the base metal, and the corrosion properties of their weld metals with and without post weld heat treatment were investigated with some electrochemical methods in 0.1% H₂SO₄ solution. The weld metal welded with E4301 filler metal exhibited the best corrosion resistance among the filler metals in the case of no heat treatment, however, its resistance was considerably decreased due to the post weld heat treatment (annealing:625°C, 2hr). In particular, the weld metal of E4316 exhibited relatively a good corrosion resistance by the post weld heat treatment.

Abstract: Three kinds of lead-free soldering tin powder particles produced by means of ultrasonic vibration atomization were studied in this paper. For tin powder particles had higher edge angle and more irregular shape which were the two most key elements that may influence the quality of soldering paste, aspect ratio and fractal dimension of those particles were treated as the facts that could reflect the morphology of soldering tin powder particles. Geometrical projected images of those particles were acquired by optical microscope and image computing were processed by morphologic method. Since particles adhesion phenomenon often occurred in actual image processing of soldering tin powder particles, Roberts operator was used for edge detection and in the meantime, Erosion method and Dilation method in morphological operation were applied to segment those adhesive particles. It was shown that the morphologic method proposed in this paper could be applied to segment those images of adhesive particles.

Abstract: Aiming at Pbfree solder Sn4.0Ag0.5Cu (in short, SAC405), the uniaxial tensile tests are accomplished with constant strain-rate under different temperature and strain-rate load conditions. The elastic-viscoplastic behaviors of SAC405 solders are studied. The rate-dependent material main properties are analyzed, such ad yield limit, tensile strength, saturation stress, etc. Partitioned constitutive model is accepted to describe the constitutive behavior of SAC405 solder. The seven parameters in partitioned model are determined by experiment data. The results of numerical simulation are fitted with the experimental values.