TY - THES

T1 - Hydrogen embrittlement in steels

T2 - state-of-the-art in theory and practice

AU - Graf, Maximilian

N1 - no embargo

PY - 2024

Y1 - 2024

N2 - In order to reduce the enormous CO2 emissions in the iron and steel production, the direct reduction of iron ore with hydrogen will be targeted in the future. This results in an increased hydrogen content in the metal components exposed to hydrogen during steel production, which may lead to a deterioration of the mechanical properties of the structural metal components, known as hydrogen embrittlement. To enable a successful transition from carbon-containing reducing agents to pure hydrogen, codes and standards are required that take into account the detrimental effects of hydrogen on structural metals in the design and dimensioning of components. In addition, codes and standards are necessary to standardize the materials testing of metallic specimens in hydrogen-containing atmospheres. In the theoretical part of this thesis, relevant codes and standards have been reviewed and the most important points have been summarized. Additionally, various materials testing methods have been evaluated for their suitability in assessing material behavior under the influence of hydrogen. Furthermore, various steels have been reviewed regarding their deterioration of mechanical properties under the influence of hydrogen. In the experimental part of this thesis, tensile tests were performed on uncharged and hydrogen-charged specimens to investigate the influence of hydrogen on a martensitic PH 13-8 Mo and an austenitic AISI 303 steel. The tensile specimens were subjected to electrochemical hydrogen charging and the total hydrogen content in the charged and uncharged specimens was determined by thermal desorption spectroscopy. The fracture surfaces were characterized by stereo microscopy and scanning electron microscopy. A pronounced sensitivity to hydrogen embrittlement was found for PH 13-8 Mo mainly due to its high strength, martensitic matrix and low austenite content. A high susceptibility to hydrogen embrittlement was also observed for AISI 303, mainly due to its insufficient nickel content and high fraction of manganese sulfide inclusions. Compared to the austenitic steel AISI 303, the martensitic steel PH 13-8 Mo showed a significantly higher hydrogen diffusion rate, but a lower hydrogen solubility. It has been shown that only diffusible hydrogen atoms lead to hydrogen embrittlement, since specimens, which were annealed after hydrogen charging exhibited the same mechanical behavior as uncharged specimens.

AB - In order to reduce the enormous CO2 emissions in the iron and steel production, the direct reduction of iron ore with hydrogen will be targeted in the future. This results in an increased hydrogen content in the metal components exposed to hydrogen during steel production, which may lead to a deterioration of the mechanical properties of the structural metal components, known as hydrogen embrittlement. To enable a successful transition from carbon-containing reducing agents to pure hydrogen, codes and standards are required that take into account the detrimental effects of hydrogen on structural metals in the design and dimensioning of components. In addition, codes and standards are necessary to standardize the materials testing of metallic specimens in hydrogen-containing atmospheres. In the theoretical part of this thesis, relevant codes and standards have been reviewed and the most important points have been summarized. Additionally, various materials testing methods have been evaluated for their suitability in assessing material behavior under the influence of hydrogen. Furthermore, various steels have been reviewed regarding their deterioration of mechanical properties under the influence of hydrogen. In the experimental part of this thesis, tensile tests were performed on uncharged and hydrogen-charged specimens to investigate the influence of hydrogen on a martensitic PH 13-8 Mo and an austenitic AISI 303 steel. The tensile specimens were subjected to electrochemical hydrogen charging and the total hydrogen content in the charged and uncharged specimens was determined by thermal desorption spectroscopy. The fracture surfaces were characterized by stereo microscopy and scanning electron microscopy. A pronounced sensitivity to hydrogen embrittlement was found for PH 13-8 Mo mainly due to its high strength, martensitic matrix and low austenite content. A high susceptibility to hydrogen embrittlement was also observed for AISI 303, mainly due to its insufficient nickel content and high fraction of manganese sulfide inclusions. Compared to the austenitic steel AISI 303, the martensitic steel PH 13-8 Mo showed a significantly higher hydrogen diffusion rate, but a lower hydrogen solubility. It has been shown that only diffusible hydrogen atoms lead to hydrogen embrittlement, since specimens, which were annealed after hydrogen charging exhibited the same mechanical behavior as uncharged specimens.

KW - Wasserstoffversprödung

KW - PH 13-8 Mo

KW - AISI 303

KW - Elektrochemische Wasserstoffbeladung

KW - Normen und Standards

KW - Zugversuch

KW - TDS

KW - REM

KW - Hydrogen embrittlement

KW - PH 13-8 Mo

KW - AISI 303

KW - Electrochemical hydrogen charging

KW - Codes and standards

KW - Tensile testing

KW - TDS

KW - SEM

U2 - 10.34901/mul.pub.2024.080

DO - 10.34901/mul.pub.2024.080

M3 - Master's Thesis

ER -