ANALYSIS OF BUTT-WELDING PROCESS OF PLATES BY USE OF VISCOPLASTIC CONSTITUTIVE RELATIONSHIP.

Butt-welding process of thin plates is analyzed by finite element method when considering coupling effect between stress (strain), temperature and liquid-solid phase tranformation. Constitutive equation employed is the modified viscoplastic one proposed by the authors which accounts for the material behavior of liquid, time-dependent inelastic solid as well as time-independent plastic one occuring in the wide range of temperature even above melting point. Calculated distributions of temperture and stresses are partly demonstrated in bird-eye views, and temperature profile and residual stresses are measured by thermocouples and by use of X-ray diffraction technique, respectively, to verify the theory proposed.