A dislocation-based constitutive model for hydrogen—deformation interactions and a study of hydrogen-induced intergranular fracture

hydrogen;fracture;weakest-link statistics

Novak, Paul M.

关键词: hydrogen;    fracture;    weakest-link statistics;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/14563/Novak_Paul.pdf?sequence=2&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

This thesis presents two models of the effect of hydrogen on materials.Both models are intended to link experimental observations of materialmicrostructure with macroscopically observable results. The first modelcreates a continuum, rate dependent plasticity model that incorporatesthe effect of hydrogen on dislocation generation, motion, andannihilation; the transient motion of hydrogen through the material isconsidered in a complete thermodynamic framework which determines thechemical potential of the diffusing hydrogen. The behavior of severalaustenitic stainless steels is considered, both in comparison withuniaxial tension experiments and in comparison with a rate independentmodel of plastic deformation ahead of a crack tip. The second model isa framework for describing the effect of hydrogen on a weakest-linkstatistical fracture model by combining the two hydrogen embrittlementmechanisms usually thought of as mutually exclusive, hydrogenenhanced localized plasticity, and hydrogen induced decohesion. Themodel is developed, implemented in a finite element analysis program,and verified against experiment and previous statistical fracturemodels. The model is used to predict the failure load of a highstrength, low alloy steel, and sets a basis for the prognosis ofstructural steel components in a hydrogen environment.