Fracture Toughness Characterization of Advanced High Strength Steels By Means of the Essential Work of Fracture (EWF)

摘要

Due to the demand for lighter structures AHSS are becoming the steels of choice on structural automotive applications. Although their sheet forming behavior has long since been under study, not much work has been done on their fracture resistance properties. It is especially true in toughness measurements since the thickness of the metal sheet does not fit the requirements of the ASTM E-399 procedure. Thus, it is very interesting to have a methodology to quantify the fracture toughness of the AHSS. In this work the EWF methodology was applied to six different AHSS (DP600, DP780, DP800, DP1180, CP800 and TRIP800). The results show that these steels can meet the requirements of the method, and therefore the values obtained for the EWF are valid. The values, in range from 570 to 217 kJ/m{sup}2, show that their toughness is high when compared to other materials such as aluminum or titanium. Thus, the EWF procedure is postulated to be a very simple methodology that can be used to evaluate the fracture toughness and to characterize the crash behavior of sheet steels.