Analisi del comportamento meccanico di lamiere saldate mediante Digital Image Correlation

  • G. Silva
  • B. Rivolta
  • E. Zappa
  • R. Gerosa
  • A. Silvestri
  • P. Mazzoleni
  • S. Gualtieri


The existence of a welded zone generally influences the local strain and stress distribution especially in case of
welding defects. A method able to measure the local deformability can hence give many important information
about the real stress and strain fields useful to improve the welded structure design. In this experimental work,
some new generation automotive steels have been considered, because of the well known welding problems
due to their unstable microstructural condition. Such materials, known as Q&P steels and available only as
thin sheets, require a suitable quenching process able to give high mechanical resistance and satisfying
deformability. Some sheet samples were welded by electron beam technique, because it is able to reduce
the width of the heat affected zone where the main microstructural changes are concentrated. From such
samples, tensile specimens were machined. During the tensile tests, the deformations were measured both by
a traditional extensometer and by a 3D Digital Image Correlation (3D DIC) technique. A preliminary investigation
of the melted and the heat affected zones resulted in small dimensions (about 10 mm) and hence the measuring
setup has been optimized in order maximize the achievable measuring resolution minimizing the resulting
uncertainty. This result can be achieved by a pattern generated by a suitable software and by an accurate
preparation of the surface where the pattern will be deposited on.