Influencia de la anisotropia en la formabilidad de acero inoxidable 439

Abstract

This work shows the influence of the normal anisotropy (“r” value) in the deep drawing of AISI 439 ferritic stainless steel sheets. In order to do so, quantitative chemical analysis, metallographic analysis, tensile mechanical properties, and the determination of the “r” value and the “n” value were carried out in two different AISI 439 steel sheets of two different suppliers. In recent years, this ferritic stainless steel has been applied in a deep drawing process of automotive components. In this way, it must be said that one of these ferritic stainless steel sheets cracked due to exhaustion of formability during deep drawing after few steps. On the other hand, the second ferritic stainless steel sheet showed neither cracking nor other type of defects. The results of the tests, which were carried out in this work, probed that the“r” value has a strong influence on the forming behaviour of ferritic steel during deep drawing. This information is very relevant because the AISI 439 standard does not consider the planar anisotropy or the strain hardening coefficient as relevant for designation, but this type of steel is being applied in many forming operations of different components.