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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of Welding and Joining
Journal Basic Information
Journal DOI :
The Korean Welding and Joining Society
Editor in Chief :
Volume & Issues
Volume 27, Issue 6 - Dec 2009
Volume 27, Issue 5 - Oct 2009
Volume 27, Issue 4 - Aug 2009
Volume 27, Issue 3 - Jun 2009
Volume 27, Issue 2 - Apr 2009
Volume 27, Issue 1 - Feb 2009
Selecting the target year
Outline of Explosion Bulge Test in Air for Welding Structure
Park, Tae-Won ; Kim, Hong-Gyu ; Hong, Sung-Suk ; Shim, In-Ok ;
Journal of Welding and Joining, volume 27, issue 6, 2009, Pages 1~6
DOI : 10.5781/KWJS.2009.27.6.001
Retrospection and Problems as Welding Engineer for 30 Years
Kim, Young-Sik ;
Journal of Welding and Joining, volume 27, issue 6, 2009, Pages 7~8
DOI : 10.5781/KWJS.2009.27.6.007
Development of Coaxial Monitoring System in Laser Arc Hybrid Welding for Automotive Body Application
Park, Young-Whan ; Rhee, Se-Hun ; Kim, Cheol-Hee ;
Journal of Welding and Joining, volume 27, issue 6, 2009, Pages 9~16
DOI : 10.5781/KWJS.2009.27.6.009
In this paper, the coaxial monitoring system to capture image of weld pool was developed in laser-arc hybrid welding. In order to obtain the reliable image, green laser was used as a illumination system and measuring components such as band pass filter, ND (Neutral Density) filter and shutter speed was designed and optimized. Using this monitoring system, weld pool images were captured according to laser power, welding speed, welding current and interspace between laser and arc through the experiment. ANOVA (Analysis of Variation) was carried out to identify the influence of process variables on bead widths extracted from captured images of monitoring system. Welding speed and current were major factor to affect weld pool.
Microstructures of Friction Stir Lap Weld in A5052-H112 Alloy
Ko, Young-Bong ; Lee, Joong-Hun ; Park, Kyeung-Chae ;
Journal of Welding and Joining, volume 27, issue 6, 2009, Pages 17~24
DOI : 10.5781/KWJS.2009.27.6.017
The Friction Stir Welding(FSW) has mainly been used for making butt joints in Al alloys. Development of Friction Stir Lap Welding(FSLW) would expand the number of applications. Microstructure of FSLW in A5052-H112 alloy was investigated under varying rotation and welding speed. As the rotation speed was increased and the welding speed was decreased, a amount of heat was increased. As a result, bead interval was narrower, bead width are larger, and experimental bead interval was almost similar to theoretical bead interval. Typical microstructures of FSLW A5052-H112 alloy consist of three zones, including Stir Zone(SZ), Thermo-Mechanically Affected Zone(TMAZ) and Heat Affected Zone(HAZ). As a amount of heat was increased, average grain size was larger in three zones. Nevertheless, the aspect ratio was almost fixed for FSLW conditions. The misorientation of SZ, HAZ and TMAZ was examined. A large number of low angle grain boundaries, which were formed by severe plastic deformation, were showed in TMAZ as comparison with SZ and HAZ. Microhardness distribution was high in order of BM, SZ, TMAZ, and HAZ. The Micro-hardness distribution in HAZ, TMAZ of upper plate were lager than lower plate. Relationship between average grain size and microhardness was almost corresponded to Hall-Petch equation.
Effect of Heat Input on Girth Welds Properties of High Strain Steel Pipe
Lee, Jin-Woo ; Song, Woo-Hyun ; Seo, Dong-Han ; Lee, Jong-Sub ;
Journal of Welding and Joining, volume 27, issue 6, 2009, Pages 25~30
DOI : 10.5781/KWJS.2009.27.6.025
SBD (Strain-based design) of pipe lines have gained world-wide attention in recent years. The present research aims to evaluate the fracture characteristics of API (America Petroleum Institute) SBD X100 girth weldment that typically applied for cold climate and deep water offshore, with the focus on the influence of heat input changing with 6kJ/cm and 10kJ/cm from GMAW (Gas Metal Arc Welding). At a low heat input at 6kJ/cm, the weld metal had Multi-phase matrix (Acicular ferrite + Banite + Martensite) that could fill up both fracture toughness and strength as reported previously. Also, the weld metal exhibited 859MPa YS (Yield strength), 108J impact toughness at
and 0.52mm CTOD (Crack Tip Open Displacement) at
. These results can be satisfied with the requirement of API SBD X100 girth weldment and Alaska pipe line project.
Redistributions of Welding Residual Stress for CTOD Specimen by Local Compression
Joo, Sung-Min ; Yoon, Byung-Hyun ; Chang, Woong-Seong ; Bang, Han-Sur ; Bang, Hee-Seon ; Ro, Chan-Seung ;
Journal of Welding and Joining, volume 27, issue 6, 2009, Pages 31~35
DOI : 10.5781/KWJS.2009.27.6.031
When conducting CTOD test, especially in thick welded steel plate, fatigue pre-cracking occasionally failed to satisfy the requirements of standards thus making the test result invalid. Internally accumulated residual stress of test piece has been thought as one of the main reasons. The propagation of fatigue crack, started from the tip of machined notch, which might have propagated irregularly due to residual stress field. To overcome this kind of difficulty three methods to modify the residual stress are suggested in standard i.e. local compression, reverse bending and stepwise high-R ratio method. In this paper not only multi pass welding but also local pre-compressing process of thick steel plate has been simulated using finite element method for clarifying variation of internal welding residual stress. The simulated results show that welding residual stress is compressive in the middle section of the model and it is predominantly increased after machining the specimen. Comparing as-welded state all component of the welding residual stress changing to compressive in the tip of machine notch whereas residual stress of the outer area remain as tensile condition relatively. Analysis results also show that this irregular residual stress distribution is improved to be more uniformly by applying local compression.
A Study for Resistance Spot Weldability of Pre-sealed Sheet Steel for Automobile Body by Using Pre-current
Park, Tae-Gyu ; Yun, Sang-Man ; Rhee, Se-Hun ;
Journal of Welding and Joining, volume 27, issue 6, 2009, Pages 36~42
DOI : 10.5781/KWJS.2009.27.6.036
In the present day, new performances are demanded for automobile body steel sheet for example, light weight, durability, resistance corrosion and environmental protection. For an improvement of resistance corrosion, European automobile companies developed pre-sealed steel in 1990's. Pre-sealed steel have organic coated layer upper zinc coated layer. Evaluating a resistance spot weldability of pre-sealed steel plate is important because resistance spot welding is used mainly in automobile body joining process. In this study, evaluating a weldability of pre-sealed steel plate was carried out using lobe diagram, dynamic resistance and high-speed image. Usually, Pre-sealed steel has poor weldability than GA steel's. To improve a weldability of pre-sealed steel sheet, pre-current was applied to welding process. Pre-current is applied prior to base-current. In conclusion, the weldability of pre-sealed steel has been improved than GA steel's by applying pre-current.
Microstructure Evolution of Cu-based BMG Coating during APS Process and Phase Analysis by Nano-indentation Test
Kim, Jung-Hwan ; Kang, Ki-Cheol ; Yoon, Sang-Hoon ; Na, Hyun-Taek ; Lee, Chang-Hee ;
Journal of Welding and Joining, volume 27, issue 6, 2009, Pages 43~48
DOI : 10.5781/KWJS.2009.27.6.043
In this study, Cu-based bulk metallic glass (BMG) coatings were deposited by atmospheric plasma spraying (APS) process with different process conditions (with- and without hydrogen gas). As adding the hydrogen gas, thermal energy in the plasma flame increased and induced difference in the melting state of the Cu-based BMG particles. The microstructure and mechanical properties of the coatings were analyzed using a scanning electron microscope (SEM) with an energy dispersive spectroscopy (EDS) and nano-indentation tester in the light of phase analysis. It was elucidated by the nano-indentation tests that un-melted region was a mainly amorphous phase which showed discrete plasticity observed as the flow serrations on the load.displacement (P - h) curves, and the curves of solidified region showed lower flow serrations as amorphous phase mingled with crystalline phase. Oxides produced during the spraying process had the highest hardness value among the phases and were well mixed with other phases resulted from the increase in melting degree.
Numerical Analysis Model for Fatigue Life Prediction of Welded Structures
Lee, Chi-Seung ; Lee, Jae-Myung ;
Journal of Welding and Joining, volume 27, issue 6, 2009, Pages 49~54
DOI : 10.5781/KWJS.2009.27.6.049
In this study, the numerical analysis model for fatigue life prediction of welded structures are presented. In order to evaluate the structural degradation of welded structures due to fatigue loading, continuum damage mechanics approach is applied. Damage evolution equation of welded structures under arbitrary fatigue loading is constructed as a unified plasticity-damage theory. Moreover, by integration of damage evolution equation regarding to stress amplitude and number of cycles, the simplified fatigue life prediction model is derived. The proposed model is compared with fatigue test results of T-joint welded structures to obtain its validation and usefulness. It is confirmed that the predicted fatigue life of T-joint welded structures are coincided well with the fatigue test results.
A Study on the Determination of Cutting Work Envelope of Articular Robot for H-beam Cutting
Park, Ju-Yong ; Lee, Yong-Gu ;
Journal of Welding and Joining, volume 27, issue 6, 2009, Pages 55~61
DOI : 10.5781/KWJS.2009.27.6.055
This study aims for determination of cutting work envelope of an articular robot for H-beam cutting. The robot has its own work envelope. The cutting of piece with groove requires the specific position of the torch which contracts the work envelope. This study suggested the new method to determine the cutting work envelope for this case. The method simplified the problem by use of the combination of inverse kinematics and forward kinematics. The method was used for cutting the H-beam with groove. The cutting work envelope was determined easily. The result was verified by 3D simulation system which implements the articular robot with 6 axes and the H-beam in the virtual shop.
Effect of Post Weld Heat Treatment for Crystal Orientation Distribution on Friction Stir Welds of Al-Mg-Si Series Aluminum Alloy Sheets
Lee, Kwang-Jin ;
Journal of Welding and Joining, volume 27, issue 6, 2009, Pages 62~67
DOI : 10.5781/KWJS.2009.27.6.062
Friction stir welding (FSW) was carried out for Al-Mg-Si series aluminum alloys which are being used for automotive body structure. Consequently, Post weld heat treatment (PWHT) was applied to the friction stir welds to evaluate the effect of the paint baking process which is one of the automotive fabrication process on friction stir welded zone (FSWZ) in 443K for 1.2Ks. Grain structure and its crystal orientation distribution was measured about both the as welded specimens and the post weld heat treated specimens. An optical microscope (OM) and an field emission scanning electron microscope (FE-SEM) was used for observing the grain structure and measuring its crystal orientation distribution, respectively. Changes on the grain structure and its crystal orientation distribution were not detected. From the present results, it was confirmed that the paint baking process after FSW do not affect on the grain structure and its crystal orientation distribution of FSWZ. The comprehensive investigations will be performed for various automotive aluminum alloys manufactured by different processes, in the future.
A Study of Weldability for Pure Titanium by Nd:YAG Laser(II) - Welding Properties of Butt Welding -
Kim, Jong-Do ; Kwak, Myung-Sub ; Song, Moo-Keun ; Park, Seung-Ha ;
Journal of Welding and Joining, volume 27, issue 6, 2009, Pages 68~73
DOI : 10.5781/KWJS.2009.27.6.068
Recently, as titanium and titanium alloys are being increasingly used in wide areas, there are on-going researches to obtain high quality weld zone. In particular, growing interest is being drawn to laser welding, which involves low heat input and large aspect ratio in various welding processes and can facilitate shield in atmospheric condition compared with electron beam welding. The first report covered the analysis of embrittlement by the bead color of weld zone through quantitative analysis of oxygen and nitrogen and measurement of hardness as basic experiment to apply laser welding to titanium. Results indicated that the element that affect embrittlement the most was nitrogen, and as embrittlement and oxygenation go on, bead color changed to silver, gold, brown, blue and gray. This study performed butt welding of pure titanium and STS304 by using 1kW CW Nd:YAG laser, and to find out basic physical properties, evaluated welding performance by laser output, welding speed, root gap and misalignment etc, and examined mechanical properties through tensile stress and Erichsen test. The reason particles of pure titanium welded metal and HAZ are greater than STS304 is because they are pure metal and do not include many impure elements that work as nuclei in case of resolidification, thus becoming coarse columnar crystals eventually. In addition, the reason STS304 requires more energy during welding than pure titanium is because the particle size of base metal is smaller.
A Study of Weldability for Pure Titanium by Nd:YAG Laser(III) - Weld Properties of Edge Welding -
Kim, Jong-Do ; Kil, Byung-Lea ; Kwak, Myung-Sub ; Song, Moo-Keun ;
Journal of Welding and Joining, volume 27, issue 6, 2009, Pages 74~79
DOI : 10.5781/KWJS.2009.27.6.074
Titanium and titanium alloy can be reproduced immediately even if oxide films(
) break apart in sea water. Therefore, since titanium demonstrates large specific strength and outstanding resistance to stress corrosion cracking, crevice corrosion, pitting and microbiologically influenced corrosion in sea water environment, it has been widely applied to heat exchanger for ships. In particular, with excellent elongation, pure titanium may be deemed as optimal material for production of heat exchanger plate which is used with wrinkles formed for efficient heat exchange. Conventional plate type heat exchanger prevented leakage of liquid through insertion of gasket between plates and mechanical tightening by bolts and nuts, but in high temperature and high pressure environment, gasket deterioration and leakage occur, so heat exchanger for LPG re-liquefaction device etc do not use gasket but weld heat exchanger plate for use. On the other hand, since welded plate cannot be separated, it is important to obtain high quality reliable welds. In addition, for better workability and production performance, lasers that can obtain weldment with large aspect ratio and demonstrate fast welding speed even in atmospheric condition not in vacuum condition are used in producing products. So far, 1st report and 2nd report compared and analyzed embrittlement degrees by bead colors of weldment through quantitative analysis of oxygen and nitrogen and measurement of hardness as fundamental experiment for the evaluation of titanium laser welding, and evaluated the welding performance and mechanical properties of butt welding. This study welded specimens in various conditions by using laser and GTA welding machine to apply edge welding to heat exchanger, and evaluated the mechanical strength through tensile stress test. As a result of tensile test, laser weldment demonstrated tensile strength 4 times higher than GTA welds, and porosity could be controlled by increasing and decreasing slope of laser power at overlap area.
Investigation on Explosion Bulge Test Results of 800 MPa Grade Pre-heat Free Welding Consumables
Park, Tae-Won ; Song, Young-Beum ; Kim, Jin-Young ; Park, Chul-Gyu ; Kim, Hee-Jin ;
Journal of Welding and Joining, volume 27, issue 6, 2009, Pages 80~86
DOI : 10.5781/KWJS.2009.27.6.080
The Cu-bearing PFS-700 steel which has yield strength over 700 MPa was developed to replace the existing submarine structural material, HY-100. The PFS-700 steel has a combination of good mechanical properties and superior weldability. Becaus of that, it can be welded without pre-heating. The application of PFS-700 steel to submarine or battle ship will give a great reduction of cost by omitting pre-heating or lowering pre-heat temperature. To develop pre-heating free welding consumables that match and take advantage of PFS-700 steel, new welding consumables have been designed for the GMAW, SAW processes and explosion bulge test(EBT) was conducted to see the reliability of welded structure. All welds were made without pre-heating, and the inter-pass temperature was below
for SAW50 and
for GMAW and SAW150. All EBT specimens show over 14% thickness reduction without through-thickness crack or crack propagation to the hole-down area. Tensile properties for all welding conditions show higher(GMAW) or similar values(SAW50, SAW150) to the base metal. Charpy impact values for the weld metal also show 163.5J(GMAW), 95.4J(SAW50) and 69.0J(SAW150), which meet the goal(higher than 50J) of this project.