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Volume 78 (2007)
- Issue 4 Pages 289-
- Issue 3 Pages 199-
- Issue 2 Pages 97-
- Issue 1 Pages 5-
Volume 78, Issue 2
Displaying 1-10 of 10 articles from this issue
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Paper
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Hirotsugu Horio, Hirotaka Minamikawa2007 Volume 78 Issue 2 Pages 97-105
Published: April 26, 2007
Released on J-STAGE: October 26, 2007
JOURNAL FREE ACCESSA noble titanium welding wire for Metal Inert Gas Welding has been developed. The wire has oxygen-enriched surface layer which contributes to improve the arc stability and the regular droplet transfer in pure argon shielding gas. The shape and appearance of weld bead are excellent and the spattering is very few. However the meltback of contact tip is concerned during MIG welding process for titanium, because of the higher electric resistance of titanium. The effects of oxygen content of oxygen-enriched layer of welding wire, contact tip temperature, mean arc voltage and contact tip to work distance (CTWD) on meltback were investigated, while phenomenon of meltback was observed by digital high speed camera (4000 frames/sec). Meltback phenomenon was occurred along the following steps. a) Sparking was generated between titanium welding wire and inner surface of contact tip. b) Feeding of welding was stopped. c) The length of welding arc was increased very rapidly and finally the contact tip was burned off. The welding wire with higher oxygen content in oxygen-enriched layer showed stable arc voltage and did not generate meltback, although the welding wire with lower oxygen content in oxygen-enriched layer arc voltage was unstable and meltback was sometimes observed. The lower mean arc voltage and longer CTWD can provide stable arc and improve meltback phenomenon.View full abstractDownload PDF (1023K) -
Akio Uenaka, Ryuzo Yamada2007 Volume 78 Issue 2 Pages 107-113
Published: April 26, 2007
Released on J-STAGE: October 26, 2007
JOURNAL FREE ACCESS19 mass% Cr ferritic stainless steel welding wire has been used for automotive exhaust systems. In proportion as the change of usage condition and variation of base material, the technical need for welding wire has intensified. With regard to solid welding wire, which achieves fine-grained weld metal in MIG welding for ferritic stainless steel, effect of chemical compositions of welding wires on droplet transfer phenomenon has been investigated. Followings were found and confirmed from image analysis and experimental works. (1) It is effective in suppressing the amount of spatter by gas emission from droplet that ΔN [mass%N-{0.519×(mass%Al)+0.292×(mass%Ti)+0.151×(mass%Nb)}] value of welding wire is controlled under 0.01mass%. (2) It is effective in suppressing the amount of spatter by irregular short-circuiting that total amount of Al and Ti content of welding wire is controlled under about 0.1 mass%. (3) Developed welding wire which chemical compositions are controlled appropriately is less spatter and fine-graind.View full abstractDownload PDF (897K) -
Ryuzo Yamada, Akio Uenaka, Tohoru Katoho2007 Volume 78 Issue 2 Pages 115-121
Published: April 26, 2007
Released on J-STAGE: October 26, 2007
JOURNAL FREE ACCESSAn image processing system with high-speed digital video camera was developed to analysis welding arc phenomena of MAG welding process. Vibration of the tip of welding wire, size of droplet, arc length, angle of the tip of welding wire, tracks and an amount of spatter are analyzed from recorded video images. A welding wire was tested with bead on plate welding to confirm the availability of the system. As a result, arc phenomena except counting an amount of spatter were successfully analyzed quantitatively. The amount of spatter estimated by the system was agreed with the tendency of outbreak of spatter.View full abstractDownload PDF (862K)
Review
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Masahiro Fukumoto2007 Volume 78 Issue 2 Pages 123-130
Published: April 26, 2007
Released on J-STAGE: October 26, 2007
JOURNAL FREE ACCESSA variety of metallic or ceramic powder particles were thermally sprayed onto the mirror polished metallic substrate surface and the effect of both substrate temperature and ambient pressure on the flattening behavior of the particle was systematically investigated. In the flattening behavior of the sprayed particle onto the substrate surface, critical conditions were recognized both in the substrate temperature and ambient pressure. That is, the flattening behavior changed transitionally from a distorted shape with splash to a disk shape without splash on that critical temperature and pressure range, respectively. The results indicate that instead of the ordinal particle oriented factors, such as particle's velocity and temperature, particle/substrate interface oriented factors like substrate temperature and ambient pressure affect more the flattening behavior of the sprayed particle. A transition temperature, Tt, and transition pressure, Pt, were defined and introduced, respectively for those critical conditions. The fact that the dependence both of transition temperature and transition pressure on the sprayed particle material had similar tendency indicated that the wetting of the substrate by the molten particles seemed to be domination in the flattening. Three dimensional transition curvature by combining both transition temperature and transition pressure dependence was proposed as a practical and effective controlling principle of the thermal spray process.View full abstractDownload PDF (880K) -
Yoshihiro Sato2007 Volume 78 Issue 2 Pages 131-139
Published: April 26, 2007
Released on J-STAGE: October 26, 2007
JOURNAL FREE ACCESSNitrogen in steel increases the yield and tensile strength, but decreases the ductility. Therefore, nitrogen has long been considered as an impurity element especially in low carbon steel. Recently, nitrogen has received an increasing attention as an alloying element to steel, as the high nitrogen steel which has been developed with the improvement of steel-making technology, reveals several beneficial effects on properties. The advantages provided by high nitrogen steels are the high yield and tensile strength without sacrificing the toughness and ductility, and the excellent pitting corrosion resistance. The high nitrogen steels have been expected as advanced materials because of their combination of superior strength, toughness and corrosion resistance. Nitrogen in steel also has an effect of stabilizing austenite, and expected as a nickel replacement element for austenitic steels in connection with the nickel shortage and nickel allergy for human body. However, it has some problems, because the high nitrogen steel is a newly developed material. The welding / joining of this material is also one of the problems, since the material is susceptible to decrease of nitrogen content, nitride precipitation and / or pores formation during thermal cycle of the welding. This review tries to make clear the problems for welding / joining of high nitrogen stainless steel, and describes the possibility of welding / joining technology of the material.View full abstractDownload PDF (1069K) -
Tomonori Miyamichi2007 Volume 78 Issue 2 Pages 141-147
Published: April 26, 2007
Released on J-STAGE: October 26, 2007
JOURNAL FREE ACCESSAluminum alloy material is used for a lot of railroad cars such as SHINKANSEN and the commuting train. The carbody is composed A6N01S extrusion of aluminum alloy material and manufactured with MIG welding process. New joining process "Friction Stir Welding (FSW)" is developed in TWI in 1991. Because FSW is a low heat input process compared with MIG welding, the distortion of welding joint can be reduced. With using the advantage of FSW, the application is started in 1998. The first application is joining parts of carbody side-panel. After the hollow shape extrusion is developed, FSW has extended to the primary parts of the carbody structure, such as roof-panel, side-panel and floor-panel. About ten years pass from the first application FSW is becoming the main joining process of the aluminum alloy carbody.View full abstractDownload PDF (960K) -
Tetsuo Takasu, Shoji Harada2007 Volume 78 Issue 2 Pages 149-158
Published: April 26, 2007
Released on J-STAGE: October 26, 2007
JOURNAL FREE ACCESSIn Japan, about seven millions baby boomers born in 1947-1949 will retire from their jobs in 2007-2009. This is called "2007 Issue". There are strong concerns to maintain technologies and skills which support high-growth economy after World War II, and to hand down their technologies and skills to younger generations in manufacturing industries. In welding industries, known as typical "3D" jobs (Dirty, Demanding and Dangerous), the productive population has been decreased by the penetration of automatic and robotic welding processes, and by the changing consciousness of the Japanese work force particularly. TOYOTA INDUSTRIES CORPORATION established in 1926 by Sakichi Toyoda where manufactures automobile (vehicle, engine, compressor), industrial equipment (material handling), textile machinery and electronics has already started to educate and train the welding workers systematically since 1996. In this system, the welders are required to be Π type employees who have technical skill, management skill and motivation, and to pass the internal and official classification tests. This paper describes the outline and fundamentals of this training system.View full abstractDownload PDF (1265K) -
Hitoshi Nishimura2007 Volume 78 Issue 2 Pages 159-166
Published: April 26, 2007
Released on J-STAGE: October 26, 2007
JOURNAL FREE ACCESSThis report introduces the technological transition and the latest state-of-the-art technology of welding machine and robot for gas shielded arc welding, targeting automotive industry. The technology, "digital" and "fusion", is leading successive technological evolution of welding machine and robot along with customer's achievements.View full abstractDownload PDF (949K) -
Hideo Kobayashi, Iwao Kawashima, Shigeko Ohtani2007 Volume 78 Issue 2 Pages 167-178
Published: April 26, 2007
Released on J-STAGE: October 26, 2007
JOURNAL FREE ACCESSDigital Manufacturing Research Center of the National Institute of Advanced Industrial Science and Technology is developing a manufacturing database which has been made public on the Internet. It covers fifteen manufacturing methods including arc welding, which are especially principal among small and medium-sized manufacturers. This report describes arc welding database, the background of the development, structure of the database system of the operation standards and the cases of various metals.View full abstractDownload PDF (1302K)
Technical Paper
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Kouji Ohya, Toshihide Maeda2007 Volume 78 Issue 2 Pages 179-187
Published: April 26, 2007
Released on J-STAGE: October 26, 2007
JOURNAL FREE ACCESSHeat resistant cast tubes have been used for ethylene cracking furnace. Creep strength, carburization resistance and anti-coking characteristics are required for ethylene cracking furnace tubes. We have developed a novel clad tube, named EST (Ethylene Super Tube), and have been increase the number of installation into the commercial furnaces. TMT (Tube Metal Temperature) and ΔP (Differential Pressure) in the practical application was compared with conventional ethylene cracking furnace tubes, followed EPMA analysis of inner surface of the tubes. Results of the practical application trials are concluded as follows. (1) EST in commercial furnaces showed lower TMT tangent and lower ΔP. The extension of run-length is estimated twice and the increase of ethylene yield is estimated for a few % by superior anti-catalytic coking. (2) PPW overlaid layer serviced for 6 years had Cr2O3 layer with no Fe. The oxide layer is considered to prevent the catalytic coke formation for a long term. (3) EST serviced for 6 years showed superior carburization resistance by high Cr content and longer tube life is expected.View full abstractDownload PDF (650K)
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