International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

The hydrogen embrittlement susceptibility of P460NL1 pressure-vessel steel was assessed by slow strain rate testing (SSRT) with in situ electrochemical hydrogen charging. An electrochemical cell integrated with a tensile testing machine was used to generate hydrogen in a 3.5 wt.% NaCl solution containing 1 g/L thiourea. Cathodic charging was applied at a constant current of −20 mA (approximately −1.4 V). SSRT was performed at a strain rate of 10⁻ ⁵ s⁻ ¹ in accordance with ASTM G129-21. Tensile specimens extracted from the base material and welded joints were tested in air and under hydrogen-charging conditions. The methodology enabled controlled hydrogen introduction during deformation of tensile probes and allowed comparison of hydrogen-assisted cracking susceptibility between base metal and welded material. Tested brocken tensile probes were subjected to determination of dissolved hydrogen. Tensile probes were first tested in the air and after that in prepared solution.
To analyse hydrogen embritlement of investigated steel hydrogen embritlement index was determined through determination of fracture elongation and reduction of Area (RA) of the brocken specimen. Light and SEM microscopy was used to analyse possible location of the present defects in material i.e. hot rolled steel. Types of non-metallic inclusions were determined too.