Damage Analysis of Third-Generation Advanced High-Strength Steel Based on the Gurson-Tvergaard-Needleman (GTN) Model

The third generation of advanced high-strength steels (AHSS) brought attention to the steel and automotive industries due to its good compromise between formability and production costs. This work evaluated a third-generation AHSS (USS CR980XG3(TM)) through microstructural and X-ray diffraction (XRD) analyses, uniaxial tensile and plane-strain tension testing, and numerical simulations. The damage behavior of this steel is described with the Gurson-Tvergaard-Needleman (GTN) model using an identification procedure based on the uniaxial tensile and initial microvoids data. The microstructure of the CR980XG3(TM) steel is composed of ferrite, martensite-austenite islands, and retained austenite with a volume fraction of 12.2%. The global formability of the CR980XG3(TM) steel, namely the product of the uniaxial tensile strength and total elongation values, is 24.3 GPa%. The Lankford coefficient shows a weak initial plastic anisotropy of the CR980XG3(TM) steel with the in-plane anisotropy close to zero (-0.079) and the normal anisotropy close to unity (0.917). The identified GTN parameters for the CR980XG3(TM) steel provided a good forecast for the limit strains defined according to ISO 12004-2 standard from the uniaxial tensile and plane-strain tension data.