Song Yan, Chai Mengyu, Han Zelin, Liu Pan
School of Chemical Engineering and Technology, Xi'an Jiaotong University, Xi'an 710049, China.
Materials (Basel). 2021 Dec 24;15(1):109. doi: 10.3390/ma15010109.
The 2.25Cr1Mo0.25V steel is a vanadium-modified 2.25Cr1Mo steel and is being widely used in the manufacture of heavy-wall hydrogenation reactors in petrochemical plants. However, the harsh service environment requires a thorough understanding of high-temperature tensile and creep behaviors of 2.25Cr1Mo0.25V steel and its weld for ensuring the safety and reliability of hydrogenation reactors. In this work, the high-temperature tensile and creep behaviors of base metal (BM) and weld metal (WM) in a 2.25Cr1Mo0.25V steel weldment used for a hydrogenation reactor were studied experimentally, paying special attention to its service temperature range of 350-500 °C. The uniaxial tensile tests under different temperatures show that the WM has higher strength and lower ductility than those of BM, due to the finer grain size in the WM. At the same time, the short-term creep tests at 550 °C reveal that the WM has a higher creep resistance than that of BM. Moreover, the creep damage mechanisms were clarified by observing the fracture surface and microstructures of crept specimens with the aid of scanning electron microscopy (SEM). The results showed that the creep damage mechanisms of both BM and WM are the initiation and growth of creep cavities at the second phase particles. Results from this work indicate that the mismatch in the high-temperature tensile strength, ductility, and creep deformation rate in 2.25Cr1Mo0.25V steel weldment needs to be considered for the design and integrity assessment of hydrogenation reactors.
2.25Cr1Mo0.25V钢是一种钒改性的2.25Cr1Mo钢，广泛应用于石油化工厂厚壁加氢反应器的制造。然而，恶劣的服役环境要求深入了解2.25Cr1Mo0.25V钢及其焊缝的高温拉伸和蠕变行为，以确保加氢反应器的安全性和可靠性。在这项工作中，对用于加氢反应器的2.25Cr1Mo0.25V钢焊件的母材（BM）和焊缝金属（WM）的高温拉伸和蠕变行为进行了实验研究，特别关注其350-500°C的服役温度范围。不同温度下的单轴拉伸试验表明，由于焊缝金属中晶粒尺寸更细，焊缝金属比母材具有更高的强度和更低的延展性。同时，550°C下的短期蠕变试验表明，焊缝金属比母材具有更高的抗蠕变性。此外，借助扫描电子显微镜（SEM）观察蠕变试样的断口和微观组织，阐明了蠕变损伤机制。结果表明，母材和焊缝金属的蠕变损伤机制均为第二相粒子处蠕变孔洞的萌生和扩展。这项工作的结果表明，在加氢反应器的设计和完整性评估中，需要考虑2.25Cr1Mo0.25V钢焊件高温拉伸强度、延展性和蠕变变形速率的不匹配问题。
