In a significant stride towards enhancing the performance and reliability of thick steel plates, researchers have developed a novel variant of NM450 steel that addresses the persistent issue of delayed cracking during flame cutting. This innovation, spearheaded by Hongyan Liu from the State Key Laboratory of Digital Steel at Northeastern University and Handan Iron and Steel Group Co, offers promising implications for the energy sector and beyond.
The traditional NM450 steel has long been a staple in various industrial applications due to its robust mechanical properties. However, the phenomenon of delayed cracking has posed a considerable challenge, particularly in thick plates. This issue arises from the interplay of hydrogen embrittlement and internal stresses, often leading to unexpected failures and compromising structural integrity.
To tackle this problem, Liu and his team introduced 0Ni-NM450 steel, a modified version that significantly reduces the manganese content to improve segregation and increases chromium content to maintain hardenability—all without the addition of nickel. “By eliminating nickel, we not only lower the alloy costs but also reduce internal stresses within the thick plate,” Liu explained. This strategic adjustment has proven to be a game-changer, enhancing the uniformity of the martensitic structure and refining the original austenite grain boundaries.
The refined microstructure of 0Ni-NM450 steel plays a crucial role in mitigating hydrogen embrittlement. Finer austenite grains decrease the diffusible hydrogen content, while high-angle grain boundaries, with their higher binding energy, further reduce the sensitivity to hydrogen embrittlement. “The enhanced resistance to hydrogen embrittlement is a key factor in preventing delayed cracking,” Liu noted. This breakthrough could have far-reaching implications for the energy sector, where the reliability of steel components is paramount.
The study, published in the journal “Materials Research Express” (translated as “Materials Research Express” in English), provides a comprehensive analysis of the microstructure and properties of both traditional NM450 steel and the optimized 0Ni-NM450 steel. By examining the factors influencing delayed cracking and the role of hydrogen embrittlement, the research offers valuable insights into the behavior of this steel alloy under specific conditions.
The findings of this study not only pave the way for enhancing steel performance in industrial applications but also propose potential strategies for preventing delayed cracking. As the energy sector continues to demand higher standards of reliability and safety, innovations like 0Ni-NM450 steel are poised to shape future developments in the field. This research underscores the importance of continuous innovation and the pursuit of advanced materials that can meet the evolving needs of modern industry.