Critical Assessment of the Effect of Atmospheric Corrosion Induced Hydrogen on Mechanical Properties of Advanced High Strength Steel

Darya Rudomilova,Gerald Luckeneder,Andreas Muhr,Josef Faderl,Ines Traxler,Gabriela Schimo-Aichhorn,Tomáš Prošek

doi:10.3390/met11010044

Abstract

Hydrogen absorption into steel during atmospheric corrosion has been of a strong concern during last decades. It is technically important to investigate if hydrogen absorbed under atmospheric exposure conditions can significantly affect mechanical properties of steels. The present work studies changes of mechanical properties of dual phase (DP) advanced high strength steel specimens with sodium chloride deposits during corrosion in humid air using Slow Strain Rate Test (SSRT). Additional annealed specimens were used as reference in order to separate the possible effect of absorbed hydrogen from that of corrosion deterioration. Hydrogen entry was monitored in parallel experiments using hydrogen electric resistance sensor (HERS) and thermal desorption mass spectrometry (TDMS). SSRT results showed a drop in elongation and tensile strength by 42% and 6%, respectively, in 27 days of atmospheric exposure. However, this decrease cannot be attributed to the effect of absorbed hydrogen despite the increase in hydrogen content with time of exposure. Cross-cut analysis revealed considerable pitting, which was suggested to be the main reason for the degradation of mechanical properties.

Highlights

Received: 9 December 2020Accepted: 23 December 2020Published: 28 December 2020Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.license (https://creativecommons.org/Hydrogen embrittlement of advanced high strength steels (AHSSs) in atmospheric exposure conditions is of high importance for automotive industry as the application of AHSSs grows steadily due to their desirable mechanical properties
Annealed specimens were h after the pre-exposure in order to remove absorbed hydrogen and the annealed at 200 C for 2 h after the pre-exposure in order to remove absorbed hydrogen ducted in drywas air conducted to avoid any corrosion andfurther hydrogen entry.and speciand the Slow Strain Rate Test (SSRT)
A longer exposure or more severe exposure conditions could lead to an increased hydrogen entry causing actual hydrogen induced deterioration of mechanical properties

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. The principal question is if a very small amount of hydrogen entering steel because of atmospheric corrosion might cause any significant change of mechanical properties. The critical hydrogen content can be used to indicate the dangerous hydrogen level causing a significant loss of mechanical properties [8,25]. In situ hydrogen monitoring allows detection of mobile hydrogen entering steel during atmospheric corrosion. The technically critical question is whether the amount of hydrogen formed in relevant atmospheric environments on corroding AHSS members is high enough to induce significant loss of mechanical properties. Diffusible hydrogen was monitored in situ using HERS and ex situ with TDMS

Materials and Methods

Atmospherically Induced Hydrogen Uptake

Slow Strain Rate Test

Fractographic

Discussion

Conclusions