Proceedings of the KWS Conference (대한용접접합학회:학술대회논문집)
The Korean Welding and Joining Society
- Semi Annual
Domain
- Materials > Casting/Welding/Joining
1996.05a
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The Joining of copper rod and zirconia tube was carried out in Ar gas atmosphere. There are two type of the joining. The one is the reaction bond consisting of Cu and zirconia was dominated by surface reaction wi th a undetctable very thin layer. It was found that copper elements were diffused to zirconia side, but that most of Z
$r^{4+}$ ions were not diffused to copper side. This result means application of a DC voltage to migrate oxygen to the copper/zirconia interface can oxidize metal at the copper /zirconia interface, and the bonding reaction between zirconia and copper oxide may occur. The other is the reaction bonding was dominated by interdiffusion with a very thick interface layer. This result means application of a DC voltage can reduce zirconia at the interface. The bonding reaction is to be an alloying between Zr and Cr. -
High Frequency Electric Resistance Welding process has been widely used in manufacturing welded steel pipes because of its high welding speed and quality. This process utilizes the skin effect as well as the proximity effect of the high frequency current in heating the skelp edge. In this study, an analytical solution of the edge temperature was obtained based on several assumptions. The assumptions includes the expontial decay of weldingcurrent from the surface and neglect of the heat loss in the welding direction. This calculation shows a good agreement with the observations made from the high speed camera. Using tile analytical model, tile heat required as a function of the welding speed and the skelp thickness was determined. These results were compared with the experimental results obtained.
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The expanding method of tube to tubesheet joint part on neclear steam generators are classified into three classes of roller expanding, explosive expanding and hydraulic expanding. After the expanded Mock-Up specimen are made by the three expanding method. The general properties, microstructure/microvickers hardness, pull-out strength, hydraulic leak pressure, of tube to tubesheet joint part were inspected. and We evaluated the operation efficiency of expansion, reproduction of expanded joint about three expanding method. Through the overall evaluation of tube to tubesheet joint part, The hydraukic expanding and explosive expanding could be certificated more useful expanding method.
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Continuous wave
$CO_2$ laser beam welding and formability of zinc coated steel sheets were investigated. First, optimal welding condition could be obtained in butt welding by using the data for heat input and welding velocity. The highest value of Erichsen test is 79.3% compare to that of base metal. Secondly, Formability of laser welds was investigated by using ball punch tester. Finally, the forming results of butt-welded sheets showed that the joining design was important to apply the laser welded blank in the automotive production. -
No Abstract, See Full Text
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Welding of corner area across the edge is a difficult problem in robotized arc welding system, especially when continuously-welded leakage-proof product is required. This paper presents the methodology of cooperation plan of an arc welding robot and 1 or 2 axis welding manipulators for corner area welding. Welding trajectory for the robot is generated using clothoid curves; symmetrical double clothoid curve or unsymmetrical clothoid curve depending on the nature of the workpiece. The clothoid curve is first formulated for the case of linear type positioning table and then applied to the case of rotary type manipulator. The methodology is then illustrated for practical downhand welding situations.
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1. The crack is inifiated at a toe notch and reptured for the skip and continuous welding. 2. Fatigue life of continuous welding is greater than that of skip welding and fatigue life of 2pad continuous welding appears 1.7 times more than that of pad continuous welding. 3. For the skip and continuous welding, fatigue than that of welding materials appears shorter than that of welding materials because of the effect of plastic strain and compressive residual stresses at the crack tip, which are generated by the over loading. 4. Inter-relationship between da/dN-ΔK and delayed phenomenon increases linearly at the state growth area of heat effect section for the skip and continuous welding.
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A study was made to examine the characteristics of base metal and stress relief cracking(SRC) of heat affected zone(HAZ) for HY-100 and Cu-bearing HSLA-100 steels. The Gleeble thermal/mechanical simulator was used to simulate the SRC/HAZ. The details of mechanical properties of base plate and SRC tested specimens were studied. The specimens were aged at
$650^{\circ}C$ for HSLA-100 steel and at 66$0^{\circ}C$ for HY-100 steel and thermal cycled from 135$0^{\circ}C$ In$25^{\circ}C$ with a cooling time of$\Delta$ $t_{800^{\circ}50}$ $0^{\circ}C$ /=21sec. corresponds to the heat input of 30kJ/cm. The thermal cycled specimens were stressed to a predetermined level of 248~600MPa and then reheated to the stress relief temperatures of 570~62$0^{\circ}C$ . The time to failure($t_{f}$ ) at a given stress level was used as a measure of SRC susceptibility. The strength, elongation and impact toughness of base plate were greater in HSLA-100 steel than in HY-100 steel. The time to failure was decreased with increasing temperature and/or stress. HSLA-100 steel was more susceptible to stress relief cracking than HY-100 steel under same conditions. It is thought to be resulted from the precipitation of$\varepsilon$ -Cu phase by dynamic self diffusion of solute atoms. Therefore, greater strain concentration at grain boundary of HSLA-100 steel results in the increased SRC susceptibility.y. -