Evaluation of local material strength property by small specimen-Application to strength prediction of spot-welded joint

摘要

This paper has introduced the tensile test technology of extra-small specimens (below 3 mm in total length) and also some examples of experimental results of each section of the spot-welded joint (the base material, the heat-affected zone and the nugget). It also showed, by conducting the finite element analysis of the spot-welded joint in which this strength property data is used, that the joint strength can be predicted with high precision by taking account of kinds of steel used. From now on, by making use of this technology, the authors are planning to design methods for improving strength, such as the development of materials superior in strength at the welded joint. They are hoping that this will contribute to the improvement of strength reliability for automobile bodies. They are also hoping to apply this test technology to not only thin steel sheet spot welding but also to other welding and bonding processes.