Modelling of nonlocal damage and failure in ductile steel sheets under multiaxial loading

Abstract The paper deals with a numerical model to investigate the influence of stress state on damage and failure in the ductile steel X5CrNi18-10. The numerical analysis is based on an anisotropic continuum damage model taking into account yield and damage criteria as well as evolution equations for plastic and damage strain rate tensors. Results of numerical simulations of biaxial experiments with the X0- and the H-specimen presented. In the experiments, formation of strain fields are monitored by digital image correlation which can be compared with numerically predicted ones to validate the numerical model. Based on the numerical analysis the strain and stress quantities in selected parts of the specimens are predicted. Analysis of damage strain variables enables prediction of fracture lines observed in the tests. Stress measures are used to explain different stress-state-dependent damage and failure mechanisms on the micro-level visualized on fracture surfaces by scanning electron microscopy.

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Modelling stress‐state dependent nonlocal damage and failure of ductile metals

PAMM ◽

10.1002/pamm.202000054 ◽

2021 ◽

Vol 20 (1) ◽

Author(s):

Marvin Nahrmann ◽

Anton Matzenmiller

Keyword(s):

Stress State ◽

Nonlocal Damage ◽

Ductile Metals ◽

Damage And Failure ◽

State Dependent

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Direct observation of Fe-Al-Zn ternary intermetallic compound and its transformation during the early stage of hot-dip galvanizing

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100151416 ◽

1993 ◽

Vol 51 ◽

pp. 1116-1117

Author(s):

C. S. Lin ◽

W. A. Chiou ◽

M. Meshii

Keyword(s):

Intermetallic Compound ◽

Reaction Rate ◽

Diffusion Rate ◽

Early Stage ◽

Zinc Bath ◽

Steel Sheets ◽

Direct Observations ◽

Solid Iron ◽

Iron And Zinc ◽

Ternary Intermetallic Compound

The galvannealed steel sheets have received ever increased attention because of their excellent post-painting corrosion resistance and good weldability. However, its powdering and flaking tendency during press forming processes strongly impairs its performance. In order to optimize the properties of galvanneal coatings, it is critical to control the reaction rate between solid iron and molten zinc.In commercial galvannealing line, aluminum is added to zinc bath to retard the diffusion rate between iron and zinc by the formation of a thin layer of Al intermetallic compound on the surface of steel at initial hot-dip galvanizing. However, the form of this compound and its transformation are still speculated. In this paper, we report the direct observations of this compound and its transformation.The specimens were prepared in a hot-dip simulator in which the steel was galvanized in the zinc bath containing 0.14 wt% of Al at a temperature of 480 °C for 5 seconds and was quenched by liquid nitrogen.

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