TY - CONF A1 - Fey, Gero T1 - Dilatometer-based welding simulation: CCT-Diagram and investigation of heat-affected zones in pipeline steels N2 - Presentation of the research project “Hydrogen-dependent mechanical properties of the weld microstructure of low-alloy steels for long-distance gas pipelines” and the present results at the Young Professionals International Conference (YPIC) of the International Institute of Welding (IIW) T2 - 2nd Online Young Welding Professional International Conference - YPIC2025 CY - Online meeting DA - 06.02.2025 KW - Pipeline steel KW - CCT KW - Dilatometry KW - Heat-affected zone PY - 2025 AN - OPUS4-62583 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fey, Gero T1 - Thermophysically Simulated Weld HAZ and CCT Diagram of High Strength Low Alloy Pipeline Steel N2 - This study investigates the suitability of low-alloy pipeline steels for hydrogen transportation, focusing on the development of weld microstructures. Previous research has been limited by a deficiency in the understanding of how different microstructural components respond to trapped hydrogen. By developing Continuous Cooling Transformation (CCT) diagrams through dilatometry analysis, this study explores the impact of t8/5-cooling times (the time between 800 °C and 500 °C) on the microstructure and mechanical properties of the HAZ compared to the base material. The findings provide valuable insights into how cooling times influence transformation temperatures and microstructure development, which, in turn, affect hydrogen diffusion and absorption. These findings establish a foundation for future investigations into hydrogen's impact on weld microstructures, including experimental studies, with the aim of optimizing welding practices and enhancing resistance to hydrogen-assisted cracking. Ultimately, this research contributes to improving the safety and reliability of hydrogen transportation systems in commonly used industrial pipeline steels. T2 - 78th IIW Annual Assembly & International Conference on Welding and Joining CY - Genoa, Italy DA - 22.06.2025 KW - Pipeline steel KW - CCT KW - HAZ KW - Dilatometry KW - Welding KW - L485ME KW - X70M PY - 2025 AN - OPUS4-63752 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fey, Gero T1 - Thermophysically Simulated Weld HAZ and CCT Diagram of High Strength Low Alloy Pipeline Steel N2 - Green produced Hydrogen is considered as a key energy carrier for the transition to a more sustainable energy supply. Large-scale infrastructure projects, such as the European Hydrogen Backbone, aim to establish a hydrogen pipeline network connecting production and consumption regions. To enable this distribution, existing and newly build pipeline networks play a crucial role. High-strength low-alloy (HSLA) pipeline steels such as L485ME (X70) are therefore faced to challenges associated with hydrogen transportation. One critical challenge in hydrogen transportation is hydrogen-assisted cracking (HAC), which is influenced by mechanical loading, hydrogen content, and the material itself. The microstructure of the steel has a significant impact on its resistance to HAC. Since pipeline tube sections are commonly joined by welding, the weld metal and heat-affected zone (HAZ) reveal different microstructures compared to the base material. In particular, the coarse grain heat affected zone (CGHAZ) is considered to be a critical zone for HAC. Therefore, the understanding of the resulting microstructure in the HAZ is essential to assess the material’s performance under hydrogen exposure. A quenching dilatometer was used to simulate the weld HAZ of an HSLA L485ME pipeline steel. The influence of cooling on the CGHAZ was investigated at a peak temperature of 1250°C using varying t8/5-cooling times (from 2 s up to 500 s), focusing on microstructural evolution and hardness. Based on these experiments, a continuous cooling transformation (CCT) diagram was constructed. Additionally, other regions of the weld HAZ were thermophysically simulated using two different t8/5-cooling times, namely 6 s and 15 s, while varying the peak temperature between 1250°C and 800°C. The resulting microstructures and hardness values were analyzed and compared. T2 - IIW Intermediate Meeting CY - Trollhättan, Sweden DA - 10.03.2025 KW - L485ME KW - Pipeline steel KW - CCT KW - Heat-affected zone KW - Dilatometry PY - 2025 AN - OPUS4-63102 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -