Title

Research Activities of JWRI

Author(s)CitationTransactions of JWRI. 2017, 46, p. 1-23

Version Type VoR
URL

https://hdl.handle.net/11094/69742

rights
Note

Osaka University Knowledge Archive : OUKA
https://ir.library.osaka-u.ac.jp/
Osaka University

Research Division of Materials Joining Process, Dep. of Energy Control of Processing

Journal of Physics D: Applied Physics, 51, (2017), 015204 (14pp).
doi:10.1088/1361-6463/aa9902

Experimental Investigation on Weld Pool Formation Process in
Plasma Keyhole Arc Welding
Nguyen Van Anh*, Shinichi Tashiro**, Bui Van Hanh***, Manabu Tanaka****Abstract (159Words)
This paper seeks to clarify weld pool formation process in PKAW. We adopted, for the first time,measurement of three-dimensional convection inside the weld pool in PKAW using X-ray
transmission systems. Two-dimensional convection on weld pool surface was also measured
using zirconia tracer particles. To discuss heat transport process in the weld pool, two-dimensionaltemperature distribution on the weld pool surface was also measured by the two-color pyrometry.
The results indicate that the shear force due to plasma flow is found to be the dominant driving
force in weld pool formation process in PKAW. Thus, the heat transport in the weld pool isconsidered to be governed by two large convective patterns near keyhole. They are formed withequal velocity of approximately 0.35 m/s and are mainly driven by shear force. Furthermore, theflow velocity of weld pool convection becomes considerably higher than that of other welding
process such as GTAW and GMAW due to larger plasma flow velocity.

Keywords
Plasma keyhole arc welding; Weld pool formation process; X-ray observation; Flow velocity
measurement; Temperature measurement(a) perspective view(b) top viewFig.1.
Three-dimensional convective patterns inside weld pool.

*
**
***
****

Graduate School Student
Assistant Professor
Hanoi University of Science and Technology
Professor

1

Research Division of Materials Joining Process, Dep. of Energy Transfer Dynamics

Journal of Applied Physics, 122 (2017) 033301
doi: 10.1063/1.4993715

Development of a Non-equilibrium 60 MHz Plasma Jet with aLong Discharge Plume
Giichiro Uchida*, Kazufumi Kawabata**, Taiki Ito**, Kosuke Takenaka***,Yuichi Setsuhara****

Abstract(182words)
High-frequency plasma jets driven by voltages in the frequency range 6–60 MHz are developed. Along plasma jet 40 mm in length is successfully produced by using a pair of ring electrodes outside
a quartz tube. The electrode pair consists of a wide power electrode and a narrow groundelectrode that is positioned at the head of the tube. The ratio of the length of the ground electrodeto the length of the power electrode must be small in order to produce the long plasma jets. The
high-frequency plasma jet is operated in a non-thermal-equilibrium state at a gas temperature ofaround 60 °C. Operation at the very-high-frequency of 60 MHz leads to a lower discharge voltage
and lower electron energy compared with the lower frequencies of 6 and 13.56 MHz. The ability ofthe very-high-frequency 60 MHz plasma jet to produce reactive oxygen and nitrogen species inwater is also investigated. High H2O2 and NO3− concentrations of more than 1 mmol/l are realizedby irradiating 3 ml of deionized water with the plasma for the short period of 2 min.

Keywords

Concentration (Pmol/l)

Plasma jet length (mm)Nonthermal plasma jet; High density plasma source; Reactive oxygen and nitrogen species
1.93 kV(a) 1.57 kV
 100 6 MHz
4.75 kV
6 MHz
DirectNot
13.56 MHz
contact
Water 80 13.56 MHz
contact
Water
2.75 kV
10 mm
10 mm surface
surface
60
MHz

(b)
 60 60 MHz
1.4 kV
HO
2 2
104

10 mm
NO
2

40
NO
1000

3


20

0

0

1

2
3
4
Voltage (kV)

5

6

10
1

Fig.1
Dependence of the plasma-jet length on theapplied peak-to-peak voltage for driving-voltage
frequencies of 6, 13.56, and 60 MHz. The Ar gas
flow rate was 3 slm. The photographs show
high-frequency plasma jets 40 mm in length fordriving-voltage frequencies of 6, 13.56, and 60
MHz. Reproduced from Journal of Applied
Physics, 122, 033301 (2017), with the permissionof AIP Publishing.
*
**
***
****

100

Associate Professor
Graduate School Student
Assistant Professor
Professor

2

1

1.2

1.4 1.6 1.8
Voltage (kV)

2

Fig.2
(a) Photographs deionized water being irradiatedby the VHF plasma jet (60 MHz). (b)Dependence of H2O2, NO2−, and NO3−
concentrations in the plasma-irradiated water on
the applied peak-to-peak voltage. The 60 MHz
plasma jet was used to irradiate 3 ml ofdeionized water for 2 min. Reproduced from
Journal of Applied Physics, 122, 033301 (2017),
with the permission of AIP Publishing.

Research Division of Materials Joining Process, Dep. of Laser Materials Processing

Optics & Laser Technology,99,(2017),326-332
https://doi.org/10.1016/j.optlastec.2017.09.019

Suppression of Dilution in Ni-Cr-Si-B Alloy Cladding Layer by
Controlling Diode Laser Beam Profile
Daichi Tanigawa*, Yoshinori Funada**, Nobuyuki Abe***, Masahiro Tsukamoto****,
Yoshihiko Hayashi*****, Hiroyuki Yamazaki******, Yoshihiro Tasumi*******, Mikio
Yoneyama*******

Abstract (148 Words)
A Ni-Cr-Si-B alloy layer was produced on a type 304 stainless steel plate by laser cladding. In
order to produce cladding layer with smooth surface and low dilution, influence of laser beam profile
on cladding layer was investigated. A laser beam with a constant spatial intensity at the focus spot
was used to suppress droplet formation during the cladding layer formation. This line spot, formed
with a focussing unit designed by our group, suppressed droplet generation. The layer formed using
this line spot with a constant spatial intensity had a much smoother surface compared to a layer
formed using a line spot with a Gaussian-like beam. In addition, the dilution of the former layer wasmuch smaller. These results indicated that a line spot with a constant spatial intensity was more
effective in producing a cladding layer with smooth surface and low dilution because it suppressed
droplet generation.

Keywords
Laser cladding, Flat-top profile, Diode laser, Surface roughness, Dilution

Fig.. Optical images of the cladding layer surfaces formed with (a) a Gaussian-like beam and (b) aflat-top beam. Cross-sections of the cladding layers in (a) and (b) are shown in (c) and (d), respectively*

Graduate School Student**
Industrial Research Institute of Ishikawa***
Specially Appointed Professor****
Professor*****
Specially Appointed Assistant Professor****** Specially Appointed Associate Professor******* Osaka Fuji Corporation3

Research Division of Materials Joining Mechanism, Dep. of Welding Mechanism

Journal of Manufacturing Processes, 26, (2017), 122–130.
doi:10.1016/j.jmapro.2017.02.007

A New Process for Design and Manufacture of Tailor-made
Functionally Graded Composites through Friction Stir Additive
Manufacturing
Abhay Sharma*, Bandari Vijendra*, Kazuhiro Ito**, Kazuyuki Kohama***, M. Ramji*,
B.V. Himasekhar Sai*

Abstract (195Words)
Motivated by the recent use of friction stirring in the manufacture of in-situ composites, a new
additive manufacturing method for the design and manufacture of tailor-made functionally graded
composites is presented.
The existing literature on the subject matter is limited to creating functional grades in the vicinity of
the weld nugget without direct control on composition and property gradients. A mathematicalmodel is developed for achieving a compositional gradient over a predefined length in a metal
matrix composite and subsequently demonstrated through the manufacture of aluminum+TiC
functionally graded composite. Progressive gradients are observed in hardness and local
mechanical properties, namely, Young’s modulus, strain hardening exponent, and yield stressobtained using the digital image correlation technique. The process mechanism is elucidated bycorrelating results of mechanical tests and electron backscatter diffraction analysis. A specificprocess condition vis-à-vis the number of passes, volume fraction, and particle size combination
may promote one or more phenomena such as continuous dynamic recrystallization, particle
fragmentation, and breaking of initial matrix grains, which eventually affect particle mixing andmatrix grain size and thus cause property gradients. The findings are expected to enable the
manufacture of functionally graded composites products of larger size.

Keywords
Functionally graded composite; Friction stirring; Additive manufacturing; Mechanical properties;
Microstructural analysis; Digital image correlation

Fig. 1.
Inverse pole figures and grain boundary misorientation maps.
*
**
***

Indian Institute of Technology Hyderabad
Professor
Assistant Professor

4Research Division of Materials Joining Mechanism, Dep. of Joint Interface Structure andFormation Mechanism

Materials and Design, 129, (2017), 151–163.
http://dx.doi.org/10.1016/j.matdes.2017.05.013

Clarification of Microstructure Evolution of Aluminum during
Friction Stir Welding using Liquid CO2 Rapid Cooling
Xiaochao Liu*, Yufeng Sun**, Hidetoshi Fujii***

Abstract
The microstructure evolution of aluminum during friction stir welding was reconstructed using tool“stop action” technique. Simultaneous liquid CO2 was used to “freeze” the weld microstructure andthe transient microstructure after “stop action”. Subsequent short-time annealing produced asituation similar to the normal cooling. The microstructure evolution during the deformation andannealing stages was investigated along the material flow and in the “frozen” weld zone,
respectively, by high-resolution electron-backscatter-diffraction technique. The results showed thatthe base material evolved into microstructures containing large amount of low angle grainഥ shear texture at the initial welding stage. With theboundaries (44.8%) with strong (7.9 times) /ഥ shear texture wasincreasing of welding strain, lamellar grain structure with strong (6.1 times) /
developed. Next, continuous dynamic recrystallization via lattice rotation with the grain <101>orientation as the rotation axis occurred under the strain relaxation condition, leading to lamellarഥ texture transformed into weakgrains conversion into equiaxed grains. Meanwhile, the strong /ഥ and  components). At the cooling stage, preferred(2.9 times) β-fiber textures (dominated by /ഥ texture.
grain growth along {112}<110> occurred, forming relatively strong (3.8 times) /

Keywords
Friction stir welding; Rapid cooling; Annealing; Microstructure evolution; Grain structure; Texture

Fig. 1. Grain structure development from LS to TS: (a–c) are the inverse pole figure maps; (d) themisorientation angle distributions and average grain size of a, b and c; (e) misorientation distributions
measured along the grain elongation directions; (f–h) are the inverse pole figures of the grains in a, b
and c for their respective shear directions.
*
**
***

Graduate school student
Specially appointed associate professor
Professor

5

Research Division of Materials Joining Mechanism, Dep. of Composites Materials Processing

Acta Materialia 140 (2017), 317-325.
doi.org/10.1016/j.actamat.2017.08.048

Length Effect of Carbon Nanotubes on the Strengthening
Mechanisms in Metal Matrix Composites
Biao Chen*, Jianghua Shen*, Lei Jia**, Shufeng Li**, Junko Umeda***, Makoto
Takahashi****, Katsuyoshi Kondoh*****

Abstract (145 Words)
In the present work, we studied the effect of the aspect ratio of carbon nanotubes (CNTs) on
strengthening aluminum metal matrix composites (Al MMCs). To this end, Al samples reinforced
with CNTs of various aspect ratios were produced via three different powder metallurgy methods.
Microstructural examination revealed that the CNTs were uniformly dispersed in the materials witha range of aspect ratios from 6.5 to 55. The tensile results showed that the CNTs exhibited a strong
strengthening effect in the composites regardless of their aspect ratios. However, the post-loading
examination and quantitative analysis indicated that there was a strengthening mechanism
transition for CNTs, which was closely associated with the aspect ratio or length of CNTs. The origin
of such transition was explored from the viewpoint of dislocation-CNTs interaction under loading.
The findings may provide a new insight in understanding the strengthening behaviors of CNTreinforced MMCs.

Keywords
Metal matrix composite; Carbon nanotubes; Strengthening Mechanism; Load transfer; Length
effect; Orowan mechanism

Fig. 1 Length changes of un-bundled CNTs on Al powder surface by mechanical milling anddependence of strength contribution by CNTs on aspect ratio or length of CNTs dispersed in Al
matrix composites fabricated by powder metallurgy route.

*
**
***
****
*****

Specially Appointed Researcher
Professor, Xi'an University of Technology
Associate Professor
LectureProfessor

6

Research Division of Materials Joining Process, Dep. of Joining Mechanics and Analyses

Journal of Materials Processing Technology, 243 (2017) 387–394.
doi:10.1016/j.jmatprotec.2016.12.021

Measurement of Residual Stress in Arc Welded Lap Joints bycosȽ X-ray Diffraction Method
Jian Lina*, Ninshu Ma**, Yongping Lei*, Hidekazu Murakawa**

Abstract (144Words)
The welding residual stress of lap joints of thin steel sheets was measured by the cosȽ X-ray
diffraction method and compared with the numerical simulation. The longitudinal residual stress in
the region near the weld is close to the yield strength of the base metal. The welding residual stress
distribution is asymmetrical on the two plates and two sides of the weld because of theasymmetrical geometry of the lap joint. A higher residual stress was observed on the lower plate oflap joints. The longitudinal residual stress has almost the uniform distribution along the weld line
except near two ends. The influencing length near two ends of the weld line is about 20–30 mm.
The maximum tensile value of the longitudinal residual stress of the lap joint of the high strength
steel TS590 is higher than that of the mild steel TS270.

Keywords:Residual stress, X-ray diffraction measurement method, Lap joints, Arc welding,
Numerical simulation

Fig. 1. Finite element model of arc weldedlap joint.
***

Fig. 2. Comparison of the computed andmeasured welding residual stress.

Beijing University of Technology
Professor, Osaka University

7

Research Division of Materials Joining Assessment, Dep. of Structural Integrity and Failure
Assessment

Theoretical and Applied Fracture Mechanics, 92, (2017), 178–184.
doi:10.1016/j.tafmec.2017.07.013

Observation of Micro-cracks beneath Fracture Surface during
Dynamic Crack Propagation
Yasuhito Takashima*, Tomoya Kawabata**, Suguru Yamada***, Fumiyoshi Minami****

Abstract (200Words)
In this study, micro-cracks generated during dynamic crack propagation were investigated for an
ESSO specimen and V-notched Charpy specimen. The ESSO test with temperature gradient andthe Charpy impact test were conducted for steel for shipbuilding. The macroscopic roughness ofthe fracture surface increases with increasing temperature. The section beneath the fracturesurface generated during dynamic brittle crack propagation was observed using a scanningelectron microscope, after cutting with a focused ion beam or grinding. Many micro-cracks can befound beneath the brittle fracture surface in the V-notched Charpy specimen. In the ESSO
specimen, which had a macroscopic flat surface, micro-cracks can be detected beneath the maincrack propagated in the temperature range from –140°C to –100°C. On the other hand, there werea few micro-cracks beneath the main crack propagated at relatively high temperature, at which thefracture surface was macroscopically rough. The number of micro-cracks in the Charpy specimen
is fewer than those in the ESSO specimen at the same temperature. The observations indicatedthat the correlations of Charpy impact properties with crack arrest performance for the ESSO
specimen was inconvincible in terms of the differences in the micro-scale fracture behavior as wellas lack of theoretical basis.

Keywords
Notched specimen; Brittle fracture; Rapid crack propagation; Cleavage micro-crack; StructuralsteelFig. 1.
Micro-cracks observed beneath the fracturesurface in Charpy and ESSO specimens.

*
Assistant Professor**
University of Tokyo***
Graduate School Student**** Professor

8Fig. 2.
Temperature dependence of number ofmicro-cracks beneath the fracture surface
generated during dynamic brittle crack
propagation.

Research Division of Materials Joining Assessment, Dep. of Joining Design and Dependability

Acta Mechanica , 228, (2017), 4213–4233.
doi: 10.1007/s00707-017-1926-0

Closest-point Projection Method for the Extended Subloading
Surface Model
Riccardo Fincato*, Seiichiro Tsutsumi**

Abstract (111Words)
This paper presents the implementation of a fully implicit integration scheme (i.e. closest-point
projection method) of an unconventional plasticity model, the Extended Subloading Surface Model.
The aim is to obtain precise solutions for elastoplastic investigations of metals subjected to cyclicloading, even for large prescribed loading conditions. A previous incomplete implicit integration
scheme (i.e. cutting-plane method) for the model was already formulated. However, this study
offers an alternative form, which increase the accuracy of the similarity center variable. The
numerical Finite Element Analyses (FEA) show local and global quadratic convergence rates,
proving the correct implementation of the integration scheme. Moreover, iso-error maps werecomputed to show the accuracy of the algorithm.

Keywords
Fatigue; Numerical techniques; Return mapping; Extended Subloading Surface; Cyclic plasticity.

Fig. 1.
Axial stress vs axial strain and relative errors per cycle for a cubic element under uniaxial cyclicloading.

Fig. 2.
Iso-error map for the stress, purely biaxial initial condition.
***

Specially Appointed Assistant Professor
Associate Professor

9Research Division of Materials Joining Assessment, Dep. of Reliability Evaluation&Simulation

Metallurgical and Materials Transactions A, 48, (2017), 5860-5869
doi: 10.1007/s11661-017-4340-2

Effect of Chemical Composition on Susceptibility to Weld
Solidification Cracking in Austenitic Weld Metal
Kota Kadoi*, Kenji Shinozaki **Abstract (146Words)
The influence of the chemical composition, especially the niobium content, chromium equivalentCreq, and nickel equivalent Nieq, on the weld solidification cracking susceptibility in the austenite
single-phase region in the Schaeffler diagram was investigated. The distributions of thesusceptibility (crack length and BTR) in the diagram revealed a region with high susceptibility tosolidification cracking. Addition of niobium enhanced the susceptibility and changed the
distribution of the susceptibility in the diagram. The BTR distribution was in good agreement withthe distribution of solidification temperature range ('T) calculated by solidification simulation. 'T
increased with increasing content of alloying elements such as niobium. The distribution of 'T was
dependent on the type of alloying element owing to the change of the partitioning behavior. The
distribution of the susceptibility in the region is controlled by the change in 'T and the segregation
behavior of niobium with the chemical composition.

Keywords
Solidification cracking susceptibility, Austenitic metal, Dissimilar weld metal, Dilution ratio,
Schaeffler diagram, Stainless steel

Fig.

Distributions of BTR and 'T in Schaeffler diagram. a) BTR. b) 'T.
***

Associate Professor
Hiroshima University

10

Smart Processing Research Center, Dep. of Smart Coating Processing

Advanced Powder Technology, 28 (2017) 50-54.
10.1016/j.apt.2016.07.017

Effect of BaF2 Powder Addition on the Synthesis of YAG
Phosphor by Mechanical Method
Kazuaki Kanai*, Yoshifumi Fukui*, Takahiro Kozawa**, Akira Kondo***, Makio Naito****Abstract (93 Words)
Here, we report on the effect of BaF2 powder addition on the mechanical synthesis of Ce3+-doped
Y3Al5O12 (Y2.97Al5O12:Ce0.033+, YAG:Ce3+) phosphors for white light emitting diodes. The YAG
phosphors were synthesized by the mechanical method using an attrition-type mill. When BaF2
was added at 6 wt% to the raw powder materials and milled, the synthesis of YAG:Ce3+ wasfavorably achieved at the vessel temperature of 255 °C, which was about 1200 °C lower than the
YAG phosphor synthesis temperature by solid-state reaction. The synthesized YAG:Ce3+ phosphor
revealed the maximum internal quantum yield of 57%.

Keywords
YAG:Ce3+; Phosphor; White light emitting diode; Attrition-type mill; Mechanical synthesis; BaF2

Fig.1. SEM image of sample B.

Fig.2. Excitation and emission spectra of YAG phosphor of sample B.
*
**
***
****

Kaneka Corporation
Assistant Professor
Specially Appointed Researcher
Professor

11

Smart Processing Research Center, Dep. of Nano/Micro Structure Control

Ceramic Interconnect and Ceramic Microsystems Technology, 13, 1, (2017), 225-231

Ultraviolet Laser Stereolithography of Alumina Lattice with a
Diamond Pattern
Soshu Kirihara*

Abstract (141Words)
In additive manufacturing of ultraviolet lithography, 2D cross sections were created throughdewaxing and sintering by high power laser drawing on spread resin paste including ceramic
nanoparticles, and 3D composite models were sterically printed by layer lamination and micro
joining. The lithographic system has been developed to obtain bulky ceramic components withfunctional geometries. As the row material of the lithography, nanometer sized ceramic particles
were dispersed in to liquid resins at 50 % in volume fraction. The resin paste was spread on a glass
substrate at 100 μm in layer thickness by a mechanically moved knife edge. The ultraviolet laser
beam of 355 nm in wavelength was adjusted at 50 μm in diameter and scanned on the pasted resin
surface. The irradiation power was changed automatically from 1 to 10 W for enough dewaxing andsintering depth for layer bonding.

Keywords
Additive manufacturing; Ceramics; Stereolithography

Fig. An alumina micro lattice with a diamond type periodic pattern fabricated by using ultraviolet stereo-lithography. The ceramic component was formed from resin paste including nanoparticles throughdewaxed and sintered by ultraviolet laser beam scanning.

*

Professor

12Smart Processing Research Center, Dep. of Smart Green Processing

J Mater Sci: Mater Electron, 28 (2017), 12606-12616.
https://doi.org/10.1007/s10854-017-7085-1

Thermal Stability of Low-temperature Sintered Joint using Sncoated Cu Particles during Isothermal Aging at 250 °C
Xiangdong Liu*, Shiqi Zhou*, Hiroshi Nishikawa**

Abstract (125Words)
We investigate the microstructural stability of a Cu–Cu joint sintered with microscale Cu particles
and Sn-coated Cu (Cu@Sn) particles during an isothermal aging. Using Cu particles and Cu@Sn
particles as die attach materials, pure Cu discs were bonded at 200 °C for 20 min with an appliedpressure of 10 MPa in a formic acid atmosphere. Then, the isothermal aging test was conducted
at 250 °C in an air atmosphere. The Cu@Sn sintered joints showed much better thermal stability
than the Cu sintered joint. The joint presented nearly 20 MPa shear strength after the aging for1000 h. The Cu3Sn IMC network suppressed the oxidation of Cu both in the sintered layer and on
the substrate, thereby maintaining the microstructural integrity of the Cu@Sn sintered joint.

Keywords
Pb-free high temperature bonding, Sn-coated Cu particle, Thermal stability, Shear strength

Fig. 1 Typical SEM images of the microscale particles used in this study: a Cu particles, b Sn-coatedCu particles, and c cross section of a Sn-coated Cu particle.

Fig. 2 Variation of the shear strength of the Cu@Sn joints and the Cu joints during the isothermal
aging test at 250 °C.
***

Graduate School Student
Associate Professor

13

Smart Processing Research Center, Dep. of Life-Innovation Materials Processing

Journal of the European Ceramic Society, 37, (2017) 5339-5345.
doi.org/10.1016/j.jeurceramsoc.2017.05.056

Spherical Porous Granules in MgO-Fe2O3-Nb2O5 System: In situ
Observation of Formation Behavior using High-temperature
Confocal Laser-scanning Microscopy
Yoshikazu Suzuki*, Hiroya Abe****, Hajime Yamamoto***, Kazuhiro Ito*****, Hiroshige
Inoue*****, Mayumi Nakamura**

Abstract (109Words)
The pyrolytic reactive granulation process, yielding ceramic spherical porous granules, is simple,
consisting of typical ceramic processing methods, viz., wet-ball milling of powders, vacuum drying,
granulation via sieving through a screen mesh, and one-step heat treatment for local reactive
sintering within each granule. Here, the microstructural development of spherical porous granules
was successfully visualized by in situ high-temperature confocal laser-scanning microscopy during
the heating up to 1400 °C in air. Based on the result of the in situ observation, a simple but
powerful size-controlling process of spherical porous granules, viz., multiscreen sieving after theheating was demonstrated. Nearly monodispersed spherical porous granules composed ofpseudobrookite-type MgFeNbO5 were easily obtained.

Keywords
Spherical porous granule (SPG)In situ observation; Confocal laser-scanning microscopy (CLSM);
Pseudobrookite; MgFeNbO5

Fig.1 Microstructure development of sphereporous granules observed by in situ
high-temperature confocal laser-scanningmicroscopy (left). Schematic illustration of the
microstructure development during the heating(right).

Reprinted from Y. Suzuki et al., Journal of the European Ceramic Society 37 (2017) pp.5339, Copyright (2017),
with permission from Elsevier.
*
**
***
****
*****

University of Tsukuba
Yonekura MFG Co.
Graduate School Student
Associate Professor
Professor

14

Hitachi Zosen Advanced Welding Technology Joint Research Chair⁐᥋ᵓ㐀ࢩ࣏ࣥࢪ࣒࢘ 2017 ㅮ₇ㄽᩥ㞟, (2017), 189-192

Development of Bead Shape Measurement Technology for
Pipe Welds
ࣃ࢖ࣉ⁐᥋㒊ࡢࣅ࣮ࢻᙧ≧ィᢏ⾡ࡢ㛤Ⓨ

Yohei ABE*, Mitsuyoshi NAKATANI **, Masahiko ADACHI ***, Kazuhiko TANI***, Hisato YUTO***㜿㒊 ὒᖹ㸪୰㇂ ගⰋ㸪㊊㐩 ᫀᙪ㸪㇂ ࿴ᙪ㸪‫ ⸨‮‬ᑦே

Abstract (103 Words)
The strength of pipe welds is assured by the throat thickness. The required throat thickness varies
according to the angle between pipes, which varies at different positions. It is difficult to measure
the throat thickness of the pipe welds by visual testing or using a weld gauge. We have developed
the bead shape measurement equipment for pipe welds. The equipment collects two-dimensional
point data on the bead shape of a weld using an optical cutting method, determines the leg lengthand throat thickness by data processing and makes a pass/fail judgment against the required
values at the measuring point.

Keywords
Inspection technique/ Bead shape measurement/ Optical cutting method/ Pipe welds
Branch pipe
SaddleHeel

Toe

Main pipe
Fillet segmente

Groove segment

Transition segment
䐦Insidetsidet45䡚55㼻

䐬
Outside

60㼻䠘ψ
ψ䠙35㼻
ψ䠙30㼻

Fig.1 Groove shape of pipe welds.

Judgment result“Failed” results are indicated in yellow.
Fig.2 Measurement result screen.
*
**
***

Specially Appointed Assistant Professor
Specially Appointed Associate Professor
Hitachi Zosen Corporation

15

90㼻
Insid

Special Budget Project of the Ministry of Education, Culture, Sports, Science and Technology,
Development Base on Creation of Life Innovation Materials for Interdisciplinary andInternational Researcher Development

International Journal of Hydrogen Energy, 42, (2017), 9493-9499.
Doi: 10.1149/2.1191613jes

Effects of NiO-loading on n-type GaN Photoanode for
Photoelectrochemical Water Splitting using Different Aqueous
Electrolyte
Kayo Koike*, Kazuhiro Yamamoto**, Satoshi Ohara***, Tomoka Kiritsu****, Kazunari
Ozasa****, Shinichiro Nakamura****, Masakazu Sugiyama*, Yoshiaki Nakano*, Katsushi
Fujii*

Abstract (165Words)
n-type GaN photoanodes used for water splitting have stability problems. One means of resolving
this is loading NiO catalyst on the n-type GaN surface. Aqueous electrolytes H2SO4, HCl, KOH,
and NaOH are usually used for photoelectrochemical water splitting. However, suitableelectrolytes for the NiO-loading on n-type GaN photoelectrode have not yet been evaluated.
Therefore, we investigated the effects of changing electrolytes used for NiO-loading in this study.
The photocurrent of NiO-loading on n-type GaN increased when KOH and NaOH electrolytes
were used. In addition, the surfaces showed no corrosion after reaction when these electrolytes
were used. However, the photocurrent was not stable using KOH electrolyte. Interestingly, stable
photocurrent was observed with when the NaOH electrolyte was used. In the case of H2SO4, thephotocurrent of GaN did not change with and without NiO. The surface morphologies becamerough because of GaN corrosion, and NiO dissolved in the H2SO4 electrolyte.

Keywords
GaN; Photoanode; Water splitting; Anodic corrosion; NiO

Fig. 1. NiO precursor nanoparticles synthesizedat Joining and Welding Research Institute,
Osaka University.
Fig. 2. The time variation of the photocurrent
density with and without NiO using 0.5M
H2SO4 and 1.0M NaOH electrolytes.
*
**
***
****

The University of Tokyo
NIMS
Specially Appointed Professor
RIKEN

16

The Project to Create Research and Educational Hubs for Innovative manufacturing in Asia

Activity Report on “The Project to Create Research and
Educational Hubs for Innovative Manufacturing in Asia”
Mihoko KATSUMATA*, Futoshi HIMI **, Yosuke KAWAHITO ***

Abstract (206Words)
In this project, the three pillars were set; 1) Establish a global network of researchers in joining
technologies across Greater Asia Region, 2) Develop new key technologies for joining adaptable
to extreme environments, 3) Implement oversea internships which tie up students from area of
science and the humanities, named as Coupling internships (CIS). Results of this year’s activities
were reported as below.
1) Total of 8 international joint researches including 2 newly commenced and 6 continuous
researches from previous years were implemented. 2 workshops with National Taiwan
University, Thailand National Metal and Material Technology Center, and one International
Symposium with the invited domestic and oversea speakers were organized. Through the Joint
Researches shown in Table 1, 34 international joint papers were posted.
2) Research on Underwater Laser Welding Technology was in the final stage to examine its qualityof underwater welding process as well as underwater cutting with invented torch and robot.
3) Coupling Internship was conducted in 5 countries; Indonesia, Vietnam, Thailand, India, andSingapore. Pictures from CIS can be found in Fig. 1 and Fig. 2.
4) Based on the networks, JWRI received 17 students in total from partner universities in Taiwan,
Thailand, India, Vietnam, Malaysia, Myanmar and Indonesia under JST Sakura Science Plan.
Table 1  List of International Joint Research in 2017
Partner University

Research Topics

King Mongkut’s University of Technology, Thonburi (Thailand)

Advanced high-strength titanium powder metallurgy materials for medical devices

Indian Institute of Technology, Hyderabad (India)

Relationship between structure and cooling rate of three-dimensional modelingusing arc welding

National Metal and Materials Technology Center (Thailand)

Stereolithographic additive manufacturing of biomaterials implants

Indian Institute of Technology, Hyderabad (India)

Relationship between mechanical properties and microstructure of welds in Twinwire GMAW welding of low carbon steel

Nanyang Technological University (Singapore)

Residual stress modeling and fatigue life prediction in laser cladding specimen

Indian Institute of Technology, Hyderabad (India)

Research on the melting phenomenon in waveform-controlled SAW

National Metal and Materials Technology Center (Thailand)

Laser welding of titanium and CFRP

National Metal and Materials Technology Center (Thailand)

Strengthening effect of 316L stainless steel composite via Selective Laser
Melting

Fig. 2 CIS India

Fig. 1 CIS Singapore
*
**
***

Specially Appointed Associate Professor
Specially Appointed Researcher
Associate Professor

17

NEDO Future Pioneering Projects

Science and Technology of Welding and Joining, (2017) 1-6.

Resistance Spot Welding of Metal/carbon-fiber-reinforced
Plastics and Applying Silane Coupling Treatment
Kimiaki NAGATSUKA*, Bolyu XIAO**, Lihui WU**, Kazuhiro NAKATA***, Shuhei SAEKI****,
Yamato KITAMOTO**** and Yoshiaki IWAMOTO****
Abstract
Dissimilar materials joining of SUS304 and carbon-fiber-reinforced plastics consisting of short fibers
and thermoplastics was performed. The materials were joined by series resistance spot welding. The
electrodes were pressed on the metal plate of the lap joint of metal/carbon-fiber-reinforced plastics.
The SUS304 plate was heated by resistance heating, causing the thermoplastic near the interface tomelt slightly because of heat conduction. SUS304 could be joined directly to carbon-fiber-reinforced
polyamide and modified polypropylene, but not to polyphenylene sulphide. The joining area increased
with an increase in the welding current and welding time, so did the tensile shear fracture load.
Furthermore, the silane coupling agent treatment of SUS304 was highly effective in increasing thejoining strength.
KEYWORDS: Series resistance spot welding/ carbon-fiber-reinforced thermoplastic/ polyamide 6/
polypropylene/ polyphenylene sulphide/ stainless steel/ dissimilar materials joining/ silane coupling________________________________________________________________________________*
Specially Appointed Assistant Professor**
Specially Appointed Researcher***
Specially Appointed Professor****
DENGENSHA TOA CO., LTD
18

Dept. of R & D Project for Environmental Resources and ECO Joining

The ASME Journal of Electronic Packaging, 139, 4 (2017) 041010–1-13
doi: 10.1115/1.4038143

Solid-state Microjoining Mechanisms of Wire Bonding and Flip
Chip Bonding
Yasuo TAKAHASHI*, Hiroki FUKUDA**, Yasuhiro YONESHIMA**, Hideki KITAMURA,
Masakatsu. MAEDA***

Abstract
Trend of micro-joining is described. The microjoining within large scale integration (LSI) packages
can be classified into three methods; wire bonding (WB), tape automated bonding (TAB), and flip
chip bonding (FCB). In the present paper, Au wire (ball) bonding, FCB, Al wire bonding and Al
ribbon bonding are discussed to understand the ultrasonic bonding mechanisms. Each type of
microjoining takes on various aspects but has common bonding mechanisms regarding friction slip,
plastic deformation, and friction heating. In the present paper, solid-state microjoining mechanisms
in Au wire (ball) bonding, FCB, Al wire bonding, and Al ribbon bonding are discussed tosystematically understand the common bonding mechanisms. Ultrasonic vibration enhances
friction slip and plastic deformation, making it possible to rapidly obtain dry interconnects. Metallic
adhesion at the central area of the bonding interface is mainly produced by the friction slip. On theother hand, the folding of the lateral side surfaces of the Au bump, Au ball, and Al wire is very
important for increasing the bonded area. The central and peripheral adhesions are achieved by aslip-and-fold mechanism. The solid-state microjoining mechanisms are discussed based on
experimental results. Fig. 1 shows scanning electron microscopic (SEM) photos of bonded top
surfaces of Au bump for understanding the slip-and-fold-mechanism in FCB.

Keywords
Micro-joining; Electronics packaging; Low temperature; Wire bonding; Flip chip bonding;
Ultrasonic; Al wire; Al ribbon

Fig. 1 SEM photos of the bonded top surfaces of Au bumps after etching the Al pads. Circles are drawn withwhite dotted lines. They express the diameter (~60μm) of the initial bonding surface (upper side of the bump). The
blackish brown area is an alloy reaction phase. (a) high load and high ultrasonic power conditions (F = 1.0 N/bump,
WUS = 300mW, t = 150ms). (b) low load and low ultrasonic power conditions (F = 0.43 N/bump, WUS = 50 mW, t =100 ms).
******Specially Appointed Professor
Graduate School Student
Nihon University

19

JWRI Cooperative Research Program, Joint Use / Research Award

Quarterly J. Japan Welding Soc.㸪⁐᥋Ꮫ఍ㄽᩥ㞟 35, 2 (2017), 47s-50s.

Study on Control of Cathode Spot Behavior in Arc Welding
Toshifumi Yuji*, Atsuhi Fujimaru*, Kentaro Yasui*, Hiroyuki Kinoshita*, Toshio Bouno**,Shinichi Tashiro***, Manabu Tanaka****Abstract (135Words)
This study aims to clarify the mechanism of oxide layer removal process by cathode spots in AC
TIG welding of aluminum plates and also to develop the technology to improve the oxide layer
removal efficiency through the control of the cathode spot behavior. As a result of the observationof cathode spots with an ultra-high-speed video camera, it is found that the cathode spot velocity
gradually increases with time during EP phase and reaches maximally 300 m/s. Furthermore, theaverage position of cathode spots is shifted toward the fringe of the weld pool in which the oxide
layer still exists and arrives there around the end of EP phase. From this result, it is consideredthat the removal of the oxide layer by cathode spots is effectively performed only around the endof EP phase.

Keywords
AC TIG welding; Aluminum; Cathode spot, Oxide layer removal;

Fig.1.

Fig.2.

Behavior of cathode spots around the end of
EP phase observed with an ultra-high-speed
video camera.

Distribution of cathode spot velocity aroundthe end of EP phase.

*
**
***
****

Miyazaki University
National Institute of Technology, Sasebo College
Assistant Professor
Professor

20

JWRI Cooperative Research Program, Joint Use / Research Award

Applied Physics B-Lasers and Optics,119,(2015),545-549
https://doi.org/10.1007/s00340-015-6059-3

Surface Morphology of Ti-6Al-4V Plate Fabricated by Vacuum
Selective Laser Melting
Y. Sato*, M. Tsukamoto**, Y. Yamashita***

Abstract (126 Words)
A plate made of Ti-6Al-4V (Ti64) was built by vacuum selective laser melting (SLM) at a pressureof 10-2 Pa. The vacuum SLM system employed a single mode fiber laser and three-axis galvanic
mirror in order to form 3D metallic structure. In order to investigate the surface morphology on the
fabricated plates, Vickers micro hardness and surface roughness Ra were measured. From theresults, the Vickers micro hardness of the fabricated plates was recorded at 391 HV, higher than
the typical 340 HV for a Ti64 plate. It was also determined that crystal orientation was evaluatedwith X-ray diffraction. From the results, the crystal orientation of powder is composed mainly ofmartensitic alpha. Diffraction peaks corresponding to β (110) were detected in vacuum SLM
processed samples.

Keywords
Power Density Crystal Orientation, Additive Manufacturing, Molten Pool, Selective Laser
Melting

Fig. Optical images of the fabricated plate surfaces with a scanning speed of 50 mm/s and a hatching
distance of 100 μm. Images (a) and (c) experienced a laser power density of 1.7x105 W/cm2, while(b) and (d) had 1.1x106 W/cm2. Images (c) and (d) are a higher magnification of (a) and (b),respectively.

*
**
***

Specially Appointed Researcher
Associate Professor
Industrial Research Institute of Ishikawa

21

JWRI Cooperative Research Program, Joint Use / Research Award

Journal of light metal welding, ㍍㔠ᒓ⁐᥋ 52, (2014), 453-462.
doi: https://doi.org/10.11283/jlwa.52.453

Dissimilar spot welding of three lapped sheets of aluminumalloy and steels by metal flow

-Application of Friction Anchor Welding to three lapped sheets ofaluminum alloy and steels㔠ᒓὶືࢆ฼⏝ࡋࡓ࢔࣑ࣝࢽ࣒࢘ྜ㔠/㗰/㗰 3 ᯛ㔜ࡡ␗✀㔠ᒓⅬ᥋ྜ-ᦶ᧿࢔࣮ࣥ࢝᥋ྜࡢ࢔࣑ࣝࢽ࣒࢘ྜ㔠/㗰/㗰 3 ᯛ㔜ࡡ⥅ᡭ࡬ࡢ㐺⏝-

Masaru SAKAMURA*, Kaoru OHISHI**, Kouhei OTA***, Yoshihiro TAKEYASU****,
Shigeyuki MIZUNARI*****, Hidetoshi FUJII******
ᆏᮧ຾㸪኱▼ 㑳, ኱⏣ ⪔ᖹ, ➉ಖ ⩏༤, Ỉᡂ 㔜㡰, ⸨஭ ⱥಇ

Abstract
A novel spot welding process for dissimilar metal lap joints using a new tool with the tip made ofspherical ceramics, i.e., “Friction Anchor Welding,” was applied to three lapped sheets thatconsisted of an Al alloy (1.0-mm-thick A5052) and two steels (0.6-mm- and 1.0-mm-thick SPCC).
Consequently, a steel projection was formed in the Al alloy sheet, and the sheets were welded at aplunge depth greater than 1.4 mm. The height of this steel projection increased with the plunge
depth when the plunge depth was less than 2.2 mm; accordingly, the weld strength increased, andthe tensile shear strength and the cross tensile strength reached approximately 3.8 kN/point and2.5 kN/point, respectively. However, when the plunge depth was greater than 2.2 mm, the tip of thesteel projection peeled off from the Al alloy, followed by cracks formation along the steel projection
and the Al alloy interface, and the weld strength consequently decreased.

Keywords
Dissimilar metals, Metal flow, Projection, Three sheets, Steel, Aluminum alloy

Fig. Cross-sectional macro image of the specimen (Pd: 2.2 mm).

*
Hiroshima Prefectural Technology Research Institute**
Hiroshima Prefectural Technology Research Institute***
Hiroshima Prefectural Technology Research Institute****
Hiroshima Prefectural Technology Research Institute*****
Hiroshima Prefectural Technology Research Institute****** Professor

22

JWRI Cooperative Research Program, Joint Use / Research Award

Quarterly J. Japan Welding Soc., 35, 2 (2017) 165s-168s

Anisotropic Damage Constitutive Law for Cleavage Failure in
Crystalline Grain by Cohesive Zone Model
Yuichi SHINTAKU*, Kenjiro TERADA**, Seiichiro TSUTSUMI***

Abstract (146Words)
The objective of this study is to propose new anisotropic damage constitutive law that
represents the separation process on cleavage plane in a polycrystalline aggregate. The proposed
law is formulated by embedding of the cohesive zone model (CZM) in a crystal plasticity
constitutive law. The separation of the cleavage plane can be realized by exponential type of the
CZM based on an atomic potential. On the other hands, the crystal plasticity constitutive law isused to simulate the deformation due to the crystalline slip on each crystallographic system. Thus,
the proposed damage constitutive law is capable of representing the microscopic mechanism
characterized by both the fracture behavior of the cleavage plane and the plastic deformation of
the crystallographic slip. It is confirmed that the proposed model enables us to simulate the crack
propagation in arbitrary directions, and the resultant anisotropic strength in a single crystal grain.

Keywords
Brittle fracture; Cleavage failure; Anisotropic damage; Crystal plasticity; Cohesive zone modelFig. 1 Crack propagation with distribution of

at final step.

Fig. 2 Apparent stress-strain curve during crack propagation in single crystalline grain.

*
**
***

Department of Engineering, University of Tsukuba
International Research Institute of Disaster Science, Tohoku University
Associate Professor

23