时效温度对SUS444超纯铁素体不锈钢冲击韧性的影响

Effect of aging temperature on impact toughness of SUS444 ultra-pure ferritic stainless steel

采用光学显微镜、扫描电镜和电子探针研究了时效温度对SUS444超纯铁素体不锈钢的显微组织及冲击韧性的影响。结果表明:SUS444不锈钢经850℃时效处理10 min后,室温冲击吸收能量从4.4 J提高至55 J,韧脆转变温度从20℃以上降低至-5℃。电子探针分析表明TiN相时效处理后转变为TiN、NbC和贫Nb相的三层复合结构,提高了其与基体界面的结合强度,导致实验钢冲击韧性的大幅提高。

The effects of aging temperature on microstructure and impact toughness of SUS444 ultra-pure ferritic stainless steel were studied by means of optical microscope, scanning electron microscopy and electron probe micro-analysis(EPMA). The results show that the impact absorbed energy at room temperature of the SUS444 stainless steel after aging at 850 ℃ for 10 min is increased from 4.4 J to 55 J, and the ductile-brittle transition temperature is reduced from above 20 ℃ to-5 ℃. The electron probe analysis results show that the TiN phase is transformed into a three-layer composite structure of TiN, NbC and poor Nb phase after aging treatment, which improves the bonding strength with the matrix interface and leads to a significantly increase in the impact toughness of the experimental steel.