Title

MICROHARDNESS-BASED EVALUATION OF THE DEFORMATION-AFFECTED ZONE IN SHEAR-CUT DP600 STEEL SHEET

MICROHARDNESS-BASED EVALUATION OF THE DEFORMATION-AFFECTED ZONE IN SHEAR-CUT DP600 STEEL SHEET

Authorship

OLIVEIRA, ANDRESA RODRIGUES DE; PONTES, PABLO SOUZA; SANTOS, RAFAEL OLIVEIRA; SILVA, FABIANE ROBERTA FREITAS DA

OLIVEIRA, ANDRESA RODRIGUES DE

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PONTES, PABLO SOUZA

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SANTOS, RAFAEL OLIVEIRA

I am this author

SILVA, FABIANE ROBERTA FREITAS DA

I am this author

DOI

10.5151/2594-5297-42128

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Abstract

The increasing demand for energy efficiency and emission reduction in the automotive industry has driven the development and application of advanced high-strength steels (AHSS). Among these, Dual-Phase (DP) steels stand out due to their excellent strength-to-ductility balance, weldability, and suitability for complex forming operations. However, one of the main limitations in the application of AHSS sheets is the occurrence of edge fractures during forming, frequently related to pre-damage introduced during punching and blanking operations. In these processes, the quality of the sheared edge—comprising the rollover, burnished, fracture, and burr zones—directly influences the material’s behavior in subsequent forming steps. Previous studies have shown that damage induced during shearing can reduce the hole expansion ratio and promote crack nucleation, especially near the fracture and burnished regions. Thus, understanding and quantifying the deformation-affected zone (DAZ) becomes crucial for improving forming reliability and modeling failure behavior. This study aims to experimentally characterize the DAZ in punched DP600 steel sheets by combining microhardness profiling with morphological analysis of the cut edge. The findings contribute to the understanding of strain localization around the sheared edge and provide essential input for fracture modeling in high-strength steel forming.

THE INCREASING DEMAND FOR ENERGY EFFICIENCY AND EMISSION REDUCTION IN THE AUTOMOTIVE INDUSTRY HAS DRIVEN THE DEVELOPMENT AND APPLICATION OF ADVANCED HIGH-STRENGTH STEELS (AHSS). AMONG THESE, DUAL-PHASE (DP) STEELS STAND OUT DUE TO THEIR EXCELLENT STRENGTH-TO-DUCTILITY BALANCE, WELDABILITY, AND SUITABILITY FOR COMPLEX FORMING OPERATIONS. HOWEVER, ONE OF THE MAIN LIMITATIONS IN THE APPLICATION OF AHSS SHEETS IS THE OCCURRENCE OF EDGE FRACTURES DURING FORMING, FREQUENTLY RELATED TO PRE-DAMAGE INTRODUCED DURING PUNCHING AND BLANKING OPERATIONS. IN THESE PROCESSES, THE QUALITY OF THE SHEARED EDGE—COMPRISING THE ROLLOVER, BURNISHED, FRACTURE, AND BURR ZONES—DIRECTLY INFLUENCES THE MATERIAL’S BEHAVIOR IN SUBSEQUENT FORMING STEPS. PREVIOUS STUDIES HAVE SHOWN THAT DAMAGE INDUCED DURING SHEARING CAN REDUCE THE HOLE EXPANSION RATIO AND PROMOTE CRACK NUCLEATION, ESPECIALLY NEAR THE FRACTURE AND BURNISHED REGIONS. THUS, UNDERSTANDING AND QUANTIFYING THE DEFORMATION-AFFECTED ZONE (DAZ) BECOMES CRUCIAL FOR IMPROVING FORMING RELIABILITY AND MODELING FAILURE BEHAVIOR. THIS STUDY AIMS TO EXPERIMENTALLY CHARACTERIZE THE DAZ IN PUNCHED DP600 STEEL SHEETS BY COMBINING MICROHARDNESS PROFILING WITH MORPHOLOGICAL ANALYSIS OF THE CUT EDGE. THE FINDINGS CONTRIBUTE TO THE UNDERSTANDING OF STRAIN LOCALIZATION AROUND THE SHEARED EDGE AND PROVIDE ESSENTIAL INPUT FOR FRACTURE MODELING IN HIGH-STRENGTH STEEL FORMING.

Keywords

DP600 steel sheet, Sheared edge, Microhardness profile, Deformation-affected zone, Punching-induced

DP600 steel sheet, Sheared edge, Microhardness profile, Deformation-affected zone, Punching-induced damage