HR3C钢运行前后组织性能分析

通过SEM、EDS、冲击韧性试验机、万能拉伸机等实验手段对国内电厂运行15 960 h的过热器HR3C钢管与供货态样品的微观组织进行观察分析, 对其抗拉强度、硬度、冲击韧性等相关性能进行研究。结果表明, 供货态HR3C晶内分布大量的NbCrN第二相颗粒, 运行15 960 h后晶界上析出颗粒状M₂₃C₆与链状M₂₃C₆, 同时HR3C的综合力学性能大幅下降, 脆性增加, M₂₃C₆颗粒的析出是其冲击韧性下降的主要原因。

Study on Microstructure and Mechanical Properties of HR3C before and after Operation

The microstructures and mechanical properties such as tensile strength, hardness and impact ductility of the overheater HR3C steel tube after 15 960-hour operation and the as-received sample were analyzed and investigated by means of SEM, EDS, impact toughness testing and universal tensile testing. The results showed that a lot of second-phase particles of NbCrN were distributed in the grains of the as-received HR3C. Granular and chain-like M₂₃C₆ carbides occurred along the grain boundaries after 15 960-hour operation. Meanwhile, the mechanical properties of HR3C decreased to a great extent, and the aging embrittlement increased. The main reason for the impact toughness degradation is the occurrence of M₂₃C₆.