时效粗、细晶Super304H钢的第二相析出行为及力学性能

Second phase precipitation behavior and mechanical properties of aged coarse-/fine-grain Super304H steel

采用预变形后固溶处理的方法制备了粗晶Super304H钢试样,对比研究了粗、细晶Super304H钢试样在700℃时效过程中的第二相析出行为及力学性能。结果表明:时效过程中,细小MX相与富Cu相颗粒主要分布于奥氏体晶内,奥氏体晶粒尺寸对其析出行为影响不大。粗晶Super304H钢中的M23C6相颗粒择优沿奥氏体晶界析出,长大速率大,时效1200 h后,呈连续网络状分布。随着时效时间的延长,粗、细晶Super304H钢试样的室温及高温拉伸强度先上升后下降,最终趋于稳定,断后伸长率单调下降。时效态粗晶Super304H钢试样的室温、高温拉伸力学性能,尤其是塑性,均明显小于时效态细晶Super304H钢试样。

The coarse-grain Super304H steel samples were prepared by the method of pre-deformation and solution treatment.Second phase precipitation behavior and mechanical properties of the coarse-/fine-grain Super304H steel samples during aging at 700℃were studied.The results show that the fine MX phase and Cu-rich phase particles are mainly distributed in the austenite grain during aging,and the austenite grain size has little effect on its precipitation behavior.The M23C6 phase particles in the coarse-grain Super304H steel are preferentially precipitated along the austenite grain boundary with a high growth rate,and are distributed in a continuous network after aging for 1200 h.With the increase of aging time,the tensile strength at room temperature and high temperature of the coarse-/fine-grain Super304H steel samples first increases and then decreases,and finally tend to be stable,and the elongation decreases monotonously.The tensile mechanical properties,especially the plasticity,of the aged coarse-grain Super304H steel samples at room temperature and high temperature are significantly lower than those of the aged fine-grain Super304H steel samples.