Offshore wind turbines (OWT) are a major goal of the energy strategy of Germany encompassing the increase of the installed wind power. OWT components are manufactured from welded steel plates with thicknesses up to 200 mm. The underlying standards and technical recommendations for construction of OWTs encompass specifications of so-called minimum waiting time (MWT) before non-destructive testing of the weld joints is allowed. Reason is the increased risk of time-delayed hydrogen-assisted cold cracking as hydrogen diffusion is very slow due to the very thick plates. The strict consideration of those long MWT up to 48 h during the construction of OWTs leads to significant financial burden (like disproportionately high costs for installer ships as well as storage problems (onshore)). In this study, weld joints made of S355 ML were examined in comparison with the offshore steel grade S460 G2+M. The aim was to optimize, i.e., reduce, the MWT before NDT considering varied heat input, hydrogen concentration and using self-restraint weld tests. This would significantly reduce the manufacturing time and costs of OWT construction. To quantify the necessary delay time until hydrogen-assisted cold cracks appear, acoustic emission analysis was applied directly after welding for at least 48 h.

海上风力涡轮机（OWT）是德国能源战略的主要目标，其中包括增加已安装的风力发电。OWT组件由厚度不超过200毫米的焊接钢板制成。OWT建造的基本标准和技术建议包括在允许对焊接接头进行无损检测之前所谓的最短等待时间（MWT）的规范。原因是由于板很厚，氢扩散非常缓慢，因此氢辅助冷裂化会增加延时的风险。在OWT的建造过程中，对那些长达48小时的MWT的严格考虑会导致巨大的财务负担（例如，安装船的成本过高，以及仓储问题（陆上））。在这个研究中，将S355 ML制成的焊接接头与海上钢种S460 G2 + M进行了比较。目的是在无损检测之前考虑变化的热量输入，氢气浓度并使用自约束焊接试验来优化（即降低）MWT。这将显着减少OWT建造的制造时间和成本。为了量化直到出现氢辅助冷裂纹所需的延迟时间，在焊接至少48 h后直接进行声发射分析。