Pearlite-driven surface-cracking and associated loss of tensile ductility in plain-carbon steels under exposure to high-pressure gaseous hydrogen

Four, hot-rolled, plain-carbon steels with varying carbon content were subjected to slow strain-rate tensile (SSRT) tests in a 95-MPa gaseous hydrogen environment at ambient temperature. The influence of pearlite volume fraction on the magnitude of hydrogeninduced degradation of the materials' strength and ductility was thereby determined. Hydrogen was seen to significantly affect strain-to-failure and reduction-in-area in all four materials, wherein such a loss of tensile ductility was ascribed to the premature initiation and subsequent propagation of surface micro-cracks as revealed by the quantitative damage evolution analyses on the post-fractured specimens. The pearlite grains on sample surfaces manifestly served as the preferential origins of hydrogen-induced micro-cracks, resulting in more considerable embrittlement in materials possessing a higher percentage of pearlite, due to the rapid coalescence of discrete embryonic damage during tensile straining. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

The study investigates the effect of hydrogen on the tensile properties of four hot-rolled plain-carbon steels with different carbon content. It was found that hydrogen significantly affects the tensile ductility of the materials, with pearlite grains on the surface serving as preferential origins of hydrogen-induced micro-cracks. Materials with a higher percentage of pearlite exhibit more considerable embrittlement due to the rapid coalescence of embryonic damage during tensile straining.