Mechanismy porušení nízkouhlíkových ocelí působením vodíku během SSRT testů

Abstract

This bachelor thesis investigates the influence of hydrogen embrittlement on boron-microalloyed 20MnCr5 case-hardened steel and compares two heats with very similar chemical compositions. Electrolytic hydrogen charging was performed, followed by Slow Strain Rate Testing (SSRT). The specimens were subjected to microstructural and fractographic analysis to examine the sites of crack initiation and propagation. Melt B had an acicular ferrite microstructure and smaller grain size, which should be more advantageous in terms of resistance to hydrogen embrittlement, but contained unfavourable sulphide morphology and a higher degree of segregation. Melt A showed better resistance to hydrogen embrittlement than melt B due to a more favourable sulphide distribution and more uniform microstructure.