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Yamada, Tomonori; Shobu, Takahisa; Yamashita, Susumu; Nishimura, Akihiko; Muramatsu, Toshiharu; Komizo, Yuichi*
no journal, ,
Residual stresses caused by welding processes are very important to keep structural health. The stresses depend heavily on the weld thermal history. Thus, we have studied mainly the hydrodynamic which affect the temperature distribution during a welding process. In this present work, we have carried out in-situ X-ray transmission imaging of a few metallic sample during laser welding. Hydrodynamics in a molten aluminum pool was observed using an intense synchrotron radiation source with tracer particles. In the laser intensity of 33 kW/cm
, steady flow which consisted of downward flow and upward flow was observed in the molten pool. The Maximum flow velocities were about 19.5 mm/s. The simultaneous observation of molten pool shape and flow velocity enabled the evaluation of convective heat transport. Estimated heat quantity caused by the convective heat transport is almost the same or more than that of heat conduction which is supported by the simulation.
Shobu, Takahisa
no journal, ,
Now we have tried to measure surface and internal stress or strain distributions in steel, ceramics and amorphous materials using synchrotron radiation facility SPring-8. Synchrotron radiation has general features which are an ultra-bright, a highly directional and a spectrally continuous, especially, we can use high energy (short wavelengths) X-rays in SPring-8. Then the evaluation of internal strain distribution up to 10 mm depth and below 0.2 mm special resolution has been performed at various beamline in SPring-8. In this presentation, I will introduce results of residual stress or strain measurement in various welding materials. Also, I will present in-situ strain measurements including welding materials.
Terada, Takaya; Yamada, Tomonori; Shobu, Takahisa; Nishimura, Akihiko
no journal, ,
no abstracts in English
Zhang, S.; Terasaki, Hidenori*; Komizo, Yuichi*
no journal, ,
In weld metal, it is important to decrease the residual stress of the welded joints because residual stress generated by welding promotes brittle fracture, stress corrosion cracking. As one of a countermeasure to use a volume expansion of martensitic transformation during low temperature transformation (LTT) has been examined. Then to establish this examination, the interplay between a solid state transformation and a stress deformation is very important. In this colloquium, we will present in-situ observation of the relationship between the stress deformation and the martensitic transformation of LTT, by using synchrotron radiation X-rays.