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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 31, Issue 6 - Dec 2013
Volume 31, Issue 5 - Oct 2013
Volume 31, Issue 4 - Aug 2013
Volume 31, Issue 3 - Jun 2013
Volume 31, Issue 2 - Apr 2013
Volume 31, Issue 1 - Feb 2013
Selecting the target year
Butt-fusing Procedures and Qualifications of High Density Polyethylene Pipe for Nuclear Power Plant Application
Oh, Young-Jin ; Park, Heung-Bae ; Shin, Ho-Sang ;
Journal of Welding and Joining, volume 31, issue 6, 2013, Pages 1~7
DOI : 10.5781/KWJS.2013.31.6.1
In nuclear power plants, lined carbon steel pipes or PCCPs (pre-stressed concrete cylinder pipes) have been widely used for sea water transport systems. However, de-bonding of linings and oxidation of PCCP could make problems in aged NPPs (nuclear power plants). Recently at several NPPs in the United States, the PCCPs or lined carbon steel pipes of the sea water or raw water system have been replaced with HDPE (high density polyethylene) pipes, which have outstanding resistance to oxidation and seismic loading. ASME B&PV Code committee developed Code Case N-755, which describes rules for the construction of buried Safety Class 3 polyethylene pressure piping systems. Although US NRC permitted HDPE materials for Class 3 buried piping, their permission was limited to only 10-year operation because of several concerns including the quality of fusion zone of HDPE. In this study, various requirements for fusion qualification test of HDPE and some regulatory issues raised during HDPE application review in foreign NPPs are introduced.
The Effects of δ-ferrite on Weldment of 9-12% Cr Steels
Ahn, Sung-Yong ; Kang, Namhyun ;
Journal of Welding and Joining, volume 31, issue 6, 2013, Pages 8~16
DOI : 10.5781/KWJS.2013.31.6.8
As the energy consumption increases rapidly, power generation needs the high energy efficiency continuously. To achieve the high efficiency of power generation, the materials used have to endure the higher temperature and pressure. The 9-12%Cr steels possess good mechanical properties, corrosion resistance, and creep strength in high temperature due to high Cr contents. Therefore, the 9-12%Cr steels are widely used for the high-temperature components in power plants. Even though the steels usually have a fully martensitic microstructure, they are susceptible to the formation of
-ferrite specifically during the welding process. The formation of
-ferrite has several detrimental effects on creep, ductility and toughness. Therefore, it is necessary to avoid its formation. As the volume fraction of
-ferrite is less than 2% in microstructure, it has the isolated island morphology and causes no significant degradation on mechanical properties. For
-ferrite above 2%, it has a polygonal shape affecting the detrimental influence on the mechanical properties. The formation of
-ferrite is affected by two factors: a chemical composition and a welding heat input. The most effective ways to get a fully martensite microstructure are to reduce the chromium equivalent less than 13.5, to keep the difference between the chromium and nickel equivalent less than 8, and to reduce the welding heat input.
Recent Study in Variation of Welding Materials for Overlay Welding
Yoo, Ho-Cheon ;
Journal of Welding and Joining, volume 31, issue 6, 2013, Pages 17~26
DOI : 10.5781/KWJS.2013.31.6.17
Recent developing tendency of overlay welding on welding materials are studied by searching of NDSL, Science Direct, KIPRIS and so on. Fe, Co, Ni and WC are selected as welding materials. Development and improvement of various new overlay welding technology, especially improvement of quality and formation of crack are introduced. Also the prospective technologies of overlay welding are anticipated.
Electrode Life Test of Resistance Spot Welding on Mg Alloy Using Dome Type Electrode
Choi, Dong-Soon ; Hwang, In-Sung ; Kim, Dong-Cheol ; Kang, Moon-Jin ;
Journal of Welding and Joining, volume 31, issue 6, 2013, Pages 27~31
DOI : 10.5781/KWJS.2013.31.6.27
Magnesium alloy is used on parts of aircraft and electronic equipment because of the highest specific strength among the common metal materials. Recently, studies about appling magnesium alloy sheet to automotive bodies are on the increase rapidly. For application to automotive bodies, researches about characteristics of resistance spot welding of magnesium alloy sheet are essential. Magnesium alloy has low boiling point, so getting sound bead shape is difficult when appling varies welding processes. Resistance spot welding is also particular about setting optimum welding conditions because of spatter generation, pores and cracks occurrence in nugget. And life of electrodes is very short because of alloying with copper that main material of electrodes. This requires frequent dressing and replacement of electrodes and decrease in productivity of resistance spot welding on magnesium alloy. Therefore in this study, for effective analysis of changes in tensile shear load and nugget size during electrode life test, evaluate detail characteristics of resistance spot welding on magnesium alloy sheet using dome type electrode.
A Study on Prediction of Fatigue Life using MFC Sensors
Lee, Ji-Hoon ; Oh, Dong-Jin ; Kim, Myung-Hyun ;
Journal of Welding and Joining, volume 31, issue 6, 2013, Pages 32~36
DOI : 10.5781/KWJS.2013.31.6.32
The large-scale structures have the possibility that there are defects such as cracks due to stress concentration caused by geometric discontinuities in the structure. In this respect, the assessment of fatigue life and the development of structural health monitoring(SHM) are very important. Fatigue design of structure is typically accomplished either using a set of stress cycle (S-N) data obtained from fatigue tests or using the fracture mechanics approach. The stress intensity factor(SIF) is required for the estimation of fatigue crack propagation life from the linear elastic fracture mechanics (LEFM) perspective. In this study, Macro Fiber Composie(MFC) sensor for the measurement of SIF of two dimensional cracks is used. The SIF based on the piezoelectric constitutive law and fracture mechanics are calculated. The measured values of the SIF are later used for the prediction of the crack propagation life. In this study, the measured value of the SIF and the fatigue life are compared with the theoretical results.
A Study on Analyzing Thermal Strain of Weldment during Cooling used at Low MS Point Weld Consumables
Ha, Yunsok ; Nam, Seongkil ; Park, Sejin ; Kwon, Changgil ;
Journal of Welding and Joining, volume 31, issue 6, 2013, Pages 37~43
DOI : 10.5781/KWJS.2013.31.6.37
This study targets to make clear the connection between MS (Martensite start) point and welding shrinkage. We approved that a Martensite-transformed weldment may not yield state under low MS point, but also admitted the limitation of numerical calculation by inherent strain approach or thermal strain approach. Therefore, new thermal strain formulae during cooling stages were made. As a thermal strain is obtained by integrating thermal extension coefficient, a constant of integration should be decided. In our suggested formulae, the origin was based on totally remained austenite, and added strain from volume changes in Martensite transformation was based on totally transformed ferrite. Through the suggested methodology, It is verified that an MS point under a critical temperature can let weld shrinkage relax and the critical value can be obtained. For supporting this process, 15 weld-consumables were made, were tested by fillet type and were measured. As a result, a positive correlation between MS point and level of weld-distortion was obtained, but it was rather weak.
Microstructure Evolution and Its Effect on Strength during Thermo-mechanical Cycling in the Weld Coarse-grained Heat-affected Zone of Ti-Nb Added HSLA Steel
Moon, Joonoh ; Lee, Changhee ;
Journal of Welding and Joining, volume 31, issue 6, 2013, Pages 44~49
DOI : 10.5781/KWJS.2013.31.6.44
The influence of thermo-mechanical cycling on the microstructure and strength in the weld coarse-grained heat affected zone (CGHAZ) of Ti-Nb added low carbon HSLA steel was explored through Vickers hardness tests, nanoindentation experiments, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis. Undeformed and deformed CGHAZs were simulated using Gleeble simulator with different heat inputs of 30kJ/cm and 300kJ/cm. At high heat input of 300kJ/cm, the CGHAZ consisted of ferrite and pearlite and then their grain sizes were not affected by deformation. At low heat input of 30kJ/cm, the CGHAZ consisted of lath martensite and then the sizes of prior austenite grain, packet and lath width decreased with deformation. In addition, the fraction of particle increased with deformation and this is because the precipitation kinetics was accelerated by deformation. Meanwhile, the Vickers and nanoindentation hardness of deformed CGHAZ with 30kJ/cm heat input were higher than those of undeformed CGHAZ, which are due to the effect of grain refinement and precipitation strengthening.
A Study on Microstructures and Cryogenic Mechanical Properties of Electron Beam Welds between Cast and Forged Inconel 718 Superalloys for Liquid Rocket Combustion Head
Hong, Hyun-Uk ; Bae, Sang-Hyun ; Kwon, Soon-Il ; Lee, Je-Hyun ; Do, Jeong-Hyeon ; Choi, Baig-Gyu ; Kim, In-Soo ; Jo, Chang-Yong ;
Journal of Welding and Joining, volume 31, issue 6, 2013, Pages 50~57
DOI : 10.5781/KWJS.2013.31.6.50
Characterization of microstructures and cryogenic mechanical properties of electro beam (EB) welds between cast and forged Inconel 718 superalloys has been investigated. Optimal EBW condition was found in the beam current range of 36~39 mA with the constant travel speed of 12 mm/s and arc voltage of 120 kV for 10 mm-thick specimens. Electron beam current lower than 25 mA caused to occur the liquation microfissuring in cast-side heat affected zone (HAZ) of EB welds. The HAZ liquation microfissure was found on the liquated grain boundaries with resolidified
eutectic constituents. EBW produced welds showing a fine dendritic structure with relatively discrete Laves phase due to fast cooling rate. After post weld aging treatment, blocky Laves phase and formation of
strengtheners were observed. Presence of primary strengthener and coarse Laves particles in PWHT weld may cause to reduce micro-plastic zone ahead of a crack, leading to a significant decrease in Charpy impact toughness at
. Fracture initiation and propagation induced by Charpy impact testing were discussed in terms of the dislocation structures ahead of crack arisen from the fractured Laves phase.
Laser Welding Characteristics of Aluminum and Copper Sheets for Lithium-ion Batteries
Kang, Minjung ; Park, Taesoon ; Kim, Cheolhee ; Kim, Jeonghan ;
Journal of Welding and Joining, volume 31, issue 6, 2013, Pages 58~64
DOI : 10.5781/KWJS.2013.31.6.58
Several joining methods involving resistance welding, laser welding, ultrasonic welding and mechanical joining are currently applied in manufacturing lithium-ion batteries. Cu and Al alloys are used for tab and bus bar materials, and laser welding characteristics for these alloys were investigated with similar and dissimilar material combinations in this study. The base materials used were Al 1050 and oxygen-free Cu 1020P alloys, and a disk laser was used with a continuous wave mode. In bead-on-plate welding of both alloys, the joint strength was higher than the strength of O tempered base material. In overlap welding, the effect of welding parameters on the tensile shear strength and bead shape was evaluated. Tensile shear strength of overlap welded joint was affected by interfacial bead width and weld defect formation. The tensile-shear specimen was fractured at the heat affected zone by selecting proper laser welding parameters.
The Effect of the Composition of Metallizing Paste on the Bonding Strength in the Joining of Al
/Cu to Cu
Yoon, Jong-Hyuk ; Park, Hyun Gyoon ;
Journal of Welding and Joining, volume 31, issue 6, 2013, Pages 65~70
DOI : 10.5781/KWJS.2013.31.6.65
In joining Alumina to copper plate by Mo-Mn metallizing process, the effects of the composition of metallizing paste on the bonding strength were investigated. The bonding strength increased with increasing Mn amount in the paste up to 20% but followed by the decrease with addition of Mn. The maximum bonding strength reached 50MPa at 20%Mn when heated to
for 60minute. The addition of Si to the metallizing powder increased the bonding strength of the joint by enhancing the mechanical bonding between the Alumina and the metallizing layer due to the decrease of layer viscosity with the addition of
. It is thought that MnO reacted with
spinel, forming a joint.
Porosity Reduction in Laser Welding of Nitrided Carbon Steel
Ahn, Young-Nam ; Kim, Cheolhee ; Lee, Wonbeom ; Kim, Jeonhan ;
Journal of Welding and Joining, volume 31, issue 6, 2013, Pages 71~76
DOI : 10.5781/KWJS.2013.31.6.71
Gas nitriding is a surface hardening process where nitrogen is introduced into the surface of a ferrous alloy. During fusion welding of nitrided carbon steel, the nitride inside weld metal is dissolved and generates nitrogen gas, which causes porosities - blow holes and pits. In this study, several laser welding processes such as weaving welding, two-pass welding, dual beam welding and laser-arc hybrid welding were investigated to elongate the weld pool to enhance nitrogen gas evacuation. The surface pits were successfully eliminated with elongated weld pool. However blowholes inside the weld metal were effective reduced but not fully disappeared.
Fracture Mode Analysis with ISB Bonding Process Parameter for 3D Packaging
Lee, Young-Kang ; Lee, Jae-Hak ; Song, Jun-Yeob ; Kim, Hyoung-Joon ;
Journal of Welding and Joining, volume 31, issue 6, 2013, Pages 77~83
DOI : 10.5781/KWJS.2013.31.6.77
3D packaging technology using TSV (Through Silicon Via)has been studied in the recent years to achieve higher performance, lower power consumption and smaller package size because electrical line is shorter electrical resistivity than any other packaging technology. To stack TSV chips vertically, reliable and robust bonding technology is required because mechanical stress and thermal stress cause fracture during the bonding process. Cu pillar/solder
-bump bonding process is usually to interconnect TSV chips vertically although it has weak shape to mechanical stress and thermal stress. In this study, we suggest Insert-Bump (ISB) bonding process newly to stack TSV chips. Through experiments, we tried to find optimal bonding conditions such as bonding temperature and bonding pressure. After ISB bonding, we observed microstructure of bump joint by SEM and then evaluated properties of bump joint by die shear test.
Effects of High Current and Welding Wire Diameter on the Magnesium Vaporization and Mechanical Properties of Al5083 Arc Welds
Kwon, Heimi ; Park, Chul-Ho ; Hong, In-Pyo ; Kang, Namhyun ;
Journal of Welding and Joining, volume 31, issue 6, 2013, Pages 84~89
DOI : 10.5781/KWJS.2013.31.6.84
The demand of LNG tank and the constituting material, i.e., the Al5083 thick plate, increased due to the rapid growth LNG market. To weld the Al5083 thick plate, the gas metal arc welding (GMAW) of high current is necessary to increase manufacturing productivity incurred by the multi pass welding. However, the arc welding vaporizes the volatile element such as magnesium (Mg). This phenomenon changes the Mg composition of the weld metal and the mechanical properties. The study investigated the weldability of Al5083 alloys after conducting high current GMAW. The Al5083 alloy was welded by using different size of welding wires and high current (800-950A). As the arc current increased from 800A to 950A, the mechanical strength decreased and the secondary dendrite arm spacing (SDAS) increased. Even though the arc current increased SDAS, the mechanical strength decreased due to the Mg loss in the weldment. The large diameter of welding wire decreased the dilution of the weld, therefore increasing the Mg content and the strength of the weld. For the reason, the content of Mg in welds was a major parameter to determine the mechanical property for the high current GMAW. For the arc current between 800A and 950A, the yield strength of the weldments showed a relationship with the weight percent of Mg content (
): Y.S = 27.9(
Development of Welding Quality Monitoring Method for TIG Cladding
Cho, Sang Myung ; Son, Min Su ; Park, Jung Hyun ;
Journal of Welding and Joining, volume 31, issue 6, 2013, Pages 90~95
DOI : 10.5781/KWJS.2013.31.6.90
Pipe inside clad welding is mainly used to the flow pipe of sub-sea or chemical plant. For the inside clad welding to the medium pipe with the diameter of about 12", TIG welding is frequently applied with filler metal. In this case, the clad welding has the very broad weld area over
. And, the non-destructive test (NDT) such as ultrasonic test (UT) or radiographic testing (RT) should be conducted on the broad weld area, and it costs very high due to the time-consuming work. Therefore, the present study investigated the variation of arc voltage to develop the in-line quality monitoring system for the pipe inside TIG cladding. The 4 experimental parameters (current, arc length, wire feed position, and shield gas flow rate) varied to observe the change of arc voltage and to establish the model for the monitoring. The arc voltage was decreased when the wire was fed to the backward eccentric position(over 2mm), and the shield gas flow rate was insufficient under 10L/min. In the case of the backward eccentric position over 2mm, the bead appearance was not good and the dilution ratio was increased due to deep penetration. When the shield gas flow rate was lower than 10L/min, the bead surface was oxidized.
Effect of Hot-stamping on Microstructures and Tensile Properties of Al-Si Coated Boron Steel Welds with Laser Source
Oh, Myeong-Hwan ; Kong, Jong-Pan ; Kwon, Min-Suck ; Kang, Chung-Yun ;
Journal of Welding and Joining, volume 31, issue 6, 2013, Pages 96~106
DOI : 10.5781/KWJS.2013.31.6.96
In this study, the effect of laser source(
and Nd:YAG) on the microstructure and tensile properties of laser welded Al-Si coated boron steel(1.2mmt) was investigated with before and after hot-stamping. In case of as welds condition, fracture occurred in base metal unrelated to the laser source. It could be explained that tensile strength of fusion zone composed of martensite and bainite is higher than that of base metal that contains a lot of ferrite despite dilution of Al and Si from coating layer to fusion zone. In case of hot-stamping condition, the fracture occurred in fusion zone irrelevant to laser source and the tensile strength was lower than hot stamped base metal. In the
(Al,Si) formed near the bond line was transformed into ferrite during hot-stamping. Therefore tensile strength of bond line is lower than that of base metal and center of fusion zone and the fracture occurred in the bond line. On the other hand, in the Nd:YAG laser welds, the higher concentration of Al formed the ferrite in the fusion zone during hot-stamping treatment. Also, the thickness of centerline was thinner than that of base metal. Therefore, it is considered that fracture occurred in centerline of fusion zone due to effect of concentration stress, and it leaded to a lower tensile strength and elongation.
A Study on the Welding Distortion Analysis According to Rib Height in Fillet Welding
Kim, Yong-Rae ; Song, Gyu-Yeong ; Wang, Chao ; Kim, Jae-Woong ;
Journal of Welding and Joining, volume 31, issue 6, 2013, Pages 107~111
DOI : 10.5781/KWJS.2013.31.6.107
The welding distortion is caused by welding heat in the structures which are widely used in shipbuilding and automotive industries, thus many researchers have proposed such methods to control the welding distortion through trials and numerical studies. The welding distortion has been the main cause of low productivity due to the structural strength degradation, apparent flaw, additional deformation caused by the process followed the current assembly step, and the increase of correction workload. The deformation of fillet welding is investigated in this study, and the influence of the rib height on the welding distortion is verified through the actual experiment. And the numerical analysis model using the FE software MSC.marc for analysis of welding distortion is proposed.
Hydrogen Embrittlement Resistance and Diffusible Hydrogen Desorption Behavior of Multipass FCA Weld Metals
Yoo, Jaeseok ; Xian, Guo ; Lee, Myungjin ; Kim, Yongdeok ; Kang, Namhyun ;
Journal of Welding and Joining, volume 31, issue 6, 2013, Pages 112~118
DOI : 10.5781/KWJS.2013.31.6.112
In this study, constant loading test (CLT) was performed to evaluate the hydrogen embrittlement resistance for multipass FCA weld metals of 600MPa tensile strength grade. The microstructures of weld metal-2 having the smallest carbon equivalent (Ceq=0.37) consisted of grain boundary ferrite and widmanstatten ferrite in the acicular ferrite matrix. The weld metal-1 having the largest Ceq=0.47, showed the microstructures of grain boundary ferrite, widmanstatten ferrite and the large amount of bainite (vol.%=19%) in the acicular ferrite matrix. The weld metal-3 having the Ceq=0.41, which was composed of grain boundary ferrite, widmanstatten ferrite, and the small amount of bainite (vol.%=9%) in the acicular ferrite matrix. Hydrogen desorption spectrometry (TDS) used to analyze the amount of diffusible hydrogen and trapping site for the hydrogen pre-charged specimens electrochemically for 24 hours. With increasing the current density of hydrogen pre-charging, the released amount of diffusible hydrogen was increased. Furthermore, as increasing carbon equivalent of weld metals, the released diffusible hydrogen was increased. The main trapping sites of diffusible hydrogen for the weld metal having a low carbon equivalent (Ceq=0.37) were grain boundaries and those of weld metals having a relatively high carbon equivalent (Ceq: 0.41~0.47) were grain boundaries and dislocation. The fracture time for the hydrogen pre-charged specimens in the constant loading test was decreased as the carbon equivalent increased from 0.37 to 0.47. This result is mainly due to the increment of bainite that is vulnerable to hydrogen embrittlement.