Análise do comportamento de chapas de pequena espessura submetidas ao passe de encruamento por laminação e posterior ensaio de tração através da simulação pelo método de elementos finitos

Abstract

Lüders bands occur after the upper yield stress and during the yield plateau in the tensile testing of aged low carbon steel sheets. The sheet forming of aged material leads to the formation of unacceptable surface defects caused by these Lüders bands; this problem is industrially solved by the so called skin pass, which is the final cold rolling of the annealed sheets with a light reduction in thickness (1 to 2%). This introduces a large number of small Lüders Bands in the sheets, which do not evolve into surface defects upon further forming. A finite element analysis (FEA) of the skin pass of aged low carbon sheets was performed, covering the development of the Lüders bands during the rolling deformation, the influence of the thickness reduction and the effect of the diameter of the rolls. Two levels of initial aging of the material were considered. Tensile testing of the sheets after the skin pass was also simulated, and the behavior of the Lüders bands already in the sheets, during the tensile strain was studied. An analysis of the necessary rolling reduction in order to eliminate the yield plateau in the tensile test was completed.