组织形态对2.25Cr-1Mo钢长期时效稳定性的影响

通过力学性能检测、微观组织分析、相分析等方法,研究了不同组织形态2.25Cr-1Mo钢在530 ℃×2000 h长期时效过程中的组织与力学性能稳定性。结果表明:随着正火冷速下降,组织中大尺寸等轴状铁素体含量增加,贝氏体含量下降。组织中贝氏体含量高时,钢的强韧性匹配良好,时效过程第二相碳化物粗化不明显,组织稳定性更高。大尺寸等轴状铁素体基体强度低,时效过程界面碳化物粗化与聚集速率快,且沿晶界呈链状分布,导致组织稳定性较差。铁素体含量＞40%,时效脆化现象显著。

Effect of microstructure on long-term aging stability of 2. 25Cr-1Mo steel

The stability of microstructure and mechanical properties of 2.25Cr-1Mo steel with different morphology during long-term aging at 530℃ for 2000 h were studied by means of mechanical properties test,microstructure analysis and phase analysis. The results show that as the normalizing cooling rate decreases,the content of large-sized equiaxed ferrite increases and the bainite content decreases. When the content of bainite in the microstructure is high,the strength and toughness of the steel are well matched,and the coarsening of secondary phase carbide is not obvious in the aging process,the microstructure stability is higher. The strength of large-sized equiaxed ferrite matrix is low,and in the aging process the interface carbide has a fast coarsening and aggregation rate and distributes along grain boundary,the microstructure stability is poor. The ferrite content is > 40%,and the aging embrittlement phenomenon is remarkable.