Interpretation of surficial shear crack propagation mechanisms in bending for Zn or AlSi coated hot press forming steels

Selim Kim, Min Cheol Jo, Seongwoo Kim, Jinkeun Oh, Sang Heon Kim, Seok Su Sohn, Sunghak Lee

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


The bending angle at the peak load is regarded as the most important parameter for evaluating bending properties of hot-press-forming (HPF) steels. However, it is not a mechanics-based parameter for the bending criterion, and the data interpretation is difficult because bending criteria in relation with microstructures and associated bending mechanisms have not been verified yet. In this study, effects of coating and baking treatments on bending angles at the peak load of three kinds of 1470 MPa-grade HPF steels were investigated by interrupted three-point bending tests coupled with direct microstructural observation. According to direct observations of sequential cracking processes of V-shaped crack (V-crack), bending procedures were classified into four stages: (1) formation of small V-crack, (2) increase in number and size of V-cracks, (3) initiation of shear-crack propagation from the V-crack tip, and (4) further propagation and opening of the shear crack. The minimum bending angle required for initiating the shear-crack propagation from the V-crack tip was defined as a critical angle, which meant the boundary between the 2nd and 3rd stages. The present bending behavior related with critical bending angle and V-cracking could be interpreted similarly by the fracture-mechanics concept, i.e., the initiation of shear-crack propagation.

Original languageEnglish
Article number11428
JournalScientific reports
Issue number1
Publication statusPublished - 2021 Dec

ASJC Scopus subject areas

  • General


Dive into the research topics of 'Interpretation of surficial shear crack propagation mechanisms in bending for Zn or AlSi coated hot press forming steels'. Together they form a unique fingerprint.

Cite this