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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 15, Issue 6 - Dec 1997
Volume 15, Issue 5 - Oct 1997
Volume 15, Issue 4 - Aug 1997
Volume 15, Issue 3 - Jun 1997
Volume 15, Issue 2 - Apr 1997
Volume 15, Issue 1 - Feb 1997
Selecting the target year
Analysis of Restraint Stress Acting on the Weldment
Journal of Welding and Joining, volume 15, issue 1, 1997, Pages 9~14
Residual Stress, Distortion, and Fracture Analysis of Welded Structures Using Finite Element Method
Journal of Welding and Joining, volume 15, issue 1, 1997, Pages 15~25
Numerical Analysis of Weldment by Considering the Convection of Welding Arc and Weld Pool
Journal of Welding and Joining, volume 15, issue 1, 1997, Pages 26~35
Welding Technology for the Process Optimization by the Computer Code SYSWELD
Journal of Welding and Joining, volume 15, issue 1, 1997, Pages 36~45
A Study on the Stress Corrosion Cracking Evaluation for Weld Joint of TMCP steel by SP-SSRT Method
Journal of Welding and Joining, volume 15, issue 1, 1997, Pages 46~54
The object of this paper is to evaluate SCC(stress corrosion cracking) susceptibility for parent metal and bond line region of weld joints which have the various weld heat input condtions in TMCP(thermo-mechanical control process) steel by SP-SSRT(small punch-slow strain rate test) method. And the SCC test results of TMCP steel are compared with those of the conventional HT50 steel which has te almost same tensile strength level like TMCP steel. The loading rate used was
mm/min and the corrosive environment was synthetic sea water. According to the test results, in the case of parent metal, TMCP steel showed higher SCC susceptibility than HT50 steel because of the high plastic strain level of ferrite microstructure obtained by accelerated cooling. And in the case of bond line, the both TMCP steel and HT50 steel showed low load-displacement behaviors and higher SCC susceptibility above 0.6. These results may be caused by theembrittled martensite structure on HT50 steel and by the coarsened grain and the proeutectoid ferrite structure obtained by the impart of accelerated cooling effect on TMCP steel.
Stress Intensity Factor for the Cracked Sheet Subjected to Normal Stress and Reinforced with a Plate by Spot Welding
Journal of Welding and Joining, volume 15, issue 1, 1997, Pages 55~65
The stress intensity factor has been calculated for the cracked plate subjected to remote normal stress and reinforced with a plate by symmetric spot welding. The solution was based on displacement compatibility condition between the cracked sheet and the reinforcement plate. It is shown that the results from the derived equation for stress intensity factor were agreed with previous solutions. The reinforcement effect gets better as a joining spot is closer to the crack tip and the other joining spots become nearer to the crack surface.
Development of an Effective Arc Sensing Algorithm for Seam-Tracking in Flux-Cored Arc Welding Process for Horizontal Fillet Joints
Journal of Welding and Joining, volume 15, issue 1, 1997, Pages 66~80
This paper describes a newly developed arc-sensing algorithm of seam-tracking for FCA W (flux-cored arc welding) horizontal fillet welding. In this algorithm, arc current and the Weighted-Are-Current (WAC) are used to adjust the position of a weld torch in directions of bead throat and weaving, respectively. The WAC, which is newly devised in this study, means that arc current in the vicinity of weaving end is more emphasized than that in the center of weaving. The reason of this is because there usually exists much noise in the center of weaving due to abrupt change of arc length in case some empty gaps exist in a fillet joint Variance analysis was performed in order to check the effect of weld parameters on arc current and the WAC. As a result, the relationships between tip-to-workpiece distance and arc current, and between weaving offset and the WAC were established.To check "the validity of the algorithm, seam-tracking experiments were performed ;mder various welding condition. The result of experiments showed a satisfactory tracking performance in the presence of empty gaps in a horizontal fillet joint.et joint.
A Study on Automatic Seam Tracking System Using Electro-Magnetic Sensor for Sheet Metal Arc Welding of Butt Joints
Journal of Welding and Joining, volume 15, issue 1, 1997, Pages 81~91
In this study, a magnetic sensor to make use of eddy current was developed to detect the weld seam of butt joint in the sheet metal arc welding. This system consist of the sensor device for detecting the weld line, the servo control device for driving the weld torch movement and the control unit. A signal processing was applied to smooth the output signal of the sensor. The weld joint was determined by using a 1st order differential method. To improve tracking accuracy of the system, moving average method which has an effect of proportional and weighted integral control was applied to a series of the weld joint positions obtained above. The weld line for tracking was generated by using data regeneration algorithm. Based on these results, each servo motor was controlled by pulse generator. From experimental results, it was revealed that this system has excellent detecting ability for weld line and seam tracking ability.
Effect of HAZ Softening Zone on Creep Rupture Properties of 1.0Cr-1.0Mo-0.25V Turbine Rotor Steels - Part I : Creep Rupture Life-
;Indacochea, J. E.;
Journal of Welding and Joining, volume 15, issue 1, 1997, Pages 92~100
Weld repair of ASTM A-470 class 8 high pressure (HP) steam turbine rotor steel has been performed to extend the service life of older fossil units. Microhardness measurements were conducted across the weldment from unaffected base metal (BM) to weld metal (WM). The hardness of the BM was VHN 253, however it dropped up to VHN 227 at the heat affected zone (HAZ) close to unaffected BM for multipass SAW. This area of hardness drop is called "siftening zone" and has a width of 0.5-0.6mm. During creep rupture test, failure occurred around the softening zone and rupture time was 772.4hr at 19Ksi (132 Mpa) and 593.deg. C. Multipass MIG and TIG welding have been employed to reduce the softening zone width. The softening zone width for MIG was 0.3-0.4mm and for TIG was zero-0.4mm depending on heat inputs. However creep rupture time was decreased as softening zone width reduced. Creep rupture time also showed a close relationship with heat inputs in TIG process. The higher heat input, the longer rupture time. Most failure occurred at intercritical HAZ (ICHAZ), however rupture location was shifted to coarse grained HAZ (CGHAZ) as heat input decreased. The rupture surface showed tearing and dimple which indicated transgranular fracture. fracture.
Effect of HAZ Softening Zone on Creep Rupture Properties of 1.0Cr-1.0Mo-0.25V Turbine Steels -Part II : Carbide Morphology-
;Indacochea, J. E.;
Journal of Welding and Joining, volume 15, issue 1, 1997, Pages 101~108
In repaired weldment of ASTM A-470 class 8 high pressure stream turbine rotor steel, creep rupture life was studied in relation with carbide morphology. Carbides were identified using carbide extraction replica method. A retired rotor has molybdenum rich carbide
, lndacochea vanadium rich carbide
, and chromium rich carbides
. Weldments ruptured at ICHAZ showed that some of carbides have been transformed into spherical types of coarsened carbides at ruptured area. Those carbides were revealed as molybdenum rich
carbide and they provided cavitation sites due to molybdenum depletion around
carbide. However coarsened
carbides were observed at ruptured area in case of ruptured at CGHAZ.
Effect of Shielding gas Composition on Arc Stability and Transfer mode of High deposition GMA Welding
Journal of Welding and Joining, volume 15, issue 1, 1997, Pages 109~115
The arc stability and the metal transfer mode of high deposition GMA welding were investigated using various compositions of shielding gas with two types of filler, ie solid wire and metal cored wire. As for a solid wire, the transfer mode changed from axial spray to rotational spray with increasing wire feed rate (welding current) and the transition current was different with the gas composition. The gas composition also affected the apparent stability of rotating arc. As for a metal cored wire, on the other hand, no transition occurred and thus spray transfer mode could be applied with the welding current over 500A (deposition rate over 300g/min). Looking for the development of high deposition GMA welding process, above results were discussed in two different ways, one is to elevate the transition current, the other is to stabilize the rotational transfer mode.
Improvement of Powder Feeding Characteristics of Fine
Powder by Modification of the Powder Feeding Systems and Characterization of the Coating Layer depending on Plasma Spraying Conditions
Journal of Welding and Joining, volume 15, issue 1, 1997, Pages 116~124
A scope of this study is to establish the optimum plasma spray conditions for fine (
powder. However, the flowability of the
powder is not so good because of irregular particle shape and fine particle size. Therefore, powder feeding system was modified by 1) change of powder feeding line material from polymer to copper 2) shorten the powder feeding tube length 3) heating the powder feeding system to
4) vibrating the powder feeding line continuously, in order to feed the fine powder homogeneously. The homogeneous powder feeding conditions were obtained with the modified powder feeding system by controlling the powder carrier gas flow and the powder flow rate indicator. The best plasma spraying conditions for the fine
powder were found out as 40kw gun power, 80 g/min. powder feed rate and 50 mm working distance after characterizing the microstructure, hardness and wear loss of the
Optimization of HVOF Spray Parameters for
Coating Powder by Experimental Design Method
Journal of Welding and Joining, volume 15, issue 1, 1997, Pages 125~134
This study was conducted by L9 orthogonal array to obtain optimum spray parameters for This study was conducted by L9 orthogonal array to obtain optimum spray parameters for
(80wt%Ni-20wt%Cr) coating powder. The factors were hydrogen flow rate, oxygen flow rate, gun-to-work distance, powder feed rate. And evaluation methods for the coating were surface roughness, oxygen concentration, micro-hardness, pore size and distribution, low angle (
) erosion rate, and microstructure of coating. The optimum HVOF spray conditions were proved as follows : hydroen flow rate ; 681 SLPM, oxygen flow rate ; 215 SLPM $H^2/O^2 ratio= 3.16), gun-to-work distance ; 22cm, powder feed rate; 25g/min. The hardness (Hv300) was 1147 and the erosion rate (
g/g. It is believed that the optimized spray conditions can be improved the wear-resistance and anti-erosion characteristics of the coating.
A Study on the Surface Harding of Aluminum Alloy - TIG Overlay Hardening of Al 5083-
Journal of Welding and Joining, volume 15, issue 1, 1997, Pages 135~148
It was attempted to improve wear resistance and durability under the load surface pressure that make a formation of the thick (mm-order) hard-surfacing layer for aluminum alloy of 5083. The thick hard layers were formed on the surface of 5083 by TIG overlay method. Al-(25.4, 33.6, 45.7 mass%) Cu filler metals which were newly developed were overlaid on two base metals forming the one bead, one layer and two layers. The investigation was made on the characteristics of hardening and wear resistance in relation to the microstructure of overlaid layers with selection of optimum overlaying condition.