熱ひずみ履歴を受けた溶接金属の機械的特性と溶接継手の変形解析への適用

Abstract

Mechanical and metallurgical heterogeneity in wled joints, which is caused by thermal prestraining cycles, have an important effect upon their deformation and strength behaviors. If the mechanical properties of steels and weld metals subjected to thermal prestraining cycles can be estimated conveniently, it is easy to analyze the deformation behaviors of weld joints by use of numerical computation procedures.In this study three kinds of weld metals, which are formed at weld joints of a carbon steel (SM41B), an austenitic stainless steel (SUS304) and a martensitic cast steel (SCS5), were used for experiments. Their mechanical properties depended upon the thermal prestraining conditions, for example, peak temperature, retention time at constant temperature, multi-thermal prestraining cycles. The experimental results indicated that elastic limit, yield stress, strength coefficient and strain hardening exponent of materials sub-jected to thermal prestraining cycles could be expressed as a function of Vickers hardness.As an application, the material constants for elastic-plastic FEM analysis were determined from the Vickers hardness distribution of weld and butt weld joint were analyzed in terms of plastic zone extension from the view of mechanical heterogeneity.