薄鋼鈑の熔接に依る熱応力(第1報)

Abstract

In this paper the thermal stress distribution, its time effect and the character of the residual stress of welded thin mild steel plates during and after welding is studied.The plate is heated suddenly till melting temperature during welding and cooled rapidly after welding, therefore, authors treat as unstationary state. It has been already approved by many literatures that there is a stress function φ as the necessary and the sufficient condition in plane thermal elastic stress. So authors try to find the stress function to satisfy the condition of welding thin mild steel plate, and can extress the following equation, ∅=-me-a2t∫∞ea2tΘdt+e-a2t∅′∞, from which authors can calcurate the stress distribution relate to arbitrary Orthogonal Cartesian co-ordinate (x.y) by following equations, xx=∂∅/∂y2, yy=∂∅/∂x2, xy=∂∅/∂x∂y where m =E.a.kE : young's modulus a : Coefficient of thermal expansionk : thermal diffusibility of the platea7 : Coefficient of coolingΘ: temperature distributiont: time after the welding is finishedφ∞: arbitrary constantxx, yy : normal stress. xy : shearing stressAuthors take.the plug welding (point thermal source) as applied practical example. As the result under consideration of the plastic flow in beyond 700°C zone besides pure elastic treatise, authors can solve the thermal stress and the residual stress distribution. This results are a good fit to experimental results in Germany and to our experimental results in regard to the radius of Luders line zone.