Hydrogen-Assisted Microdamage of Eutectoid Pearlitic Steel in the Presence of Notches: The Tearing Topography Surface

This paper studies the hydrogen-assisted microdamage (HAMD) in fully-pearlitic steel. A detailed analysis is provided of the HAMD region in axisymmetric round-notched samples of high-strength eutectoid pearlitic steel under hydrogen embrittlement environmental conditions. The microscopic appearance and evolution of the hydrogen affected region is analyzed from the initiation (sub-critical) to the fracture (critical) situations. The use of very distinct notched samples and their associated stress distributions in the vicinity of the notch tip allows for a study of the key role of the triaxial stress state on hydrogen diffusion and micro-cracking (or micro-damage). The microscopic appearance of the hydrogen-affected zone (the so-called tearing topography surface) resembles micro-damage, micro-cracking or micro-tearing at a micro- or nano-scale due to hydrogen degradation, thus affecting the notch tensile strength and producing hydrogen embrittlement. A micromechanical model is proposed to explain these hydrogen effects on the material on the basis of the lamellar micro- and nano-structure of the pearlitic steel.

Automated summary

This paper investigates the hydrogen-assisted microdamage (HAMD) in fully-pearlitic steel. Detailed analysis is conducted on the HAMD region in axisymmetric round-notched samples of high-strength eutectoid pearlitic steel under hydrogen embrittlement environmental conditions. The microstructural changes from initiation to fracture situations due to hydrogen degradation are examined, and the role of triaxial stress state on hydrogen diffusion and micro-cracking is studied.