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采用高分辨透射电镜(HRTEM)和原子探针层析技术(APT)等分析手段研究了一种多相强化型马氏体时效不锈钢时效过程中的元素偏聚特征及其与材料力学和耐蚀性能的关系.结果表明,马氏体时效不锈钢在时效过程中析出3种强化相:富Mo的R′相、Ni3Ti金属间化合物h相和富Cr的a′相.其中R′相与h相一起形成核壳状结构,a′相则单独弥散分布于基体中.时效时间延长至40 h后,主要强化相h相的成分、数量密度和等效半径基本稳定,同时马氏体时效不锈钢的强度不再发生明显的变化,这种优异的抗过时效能力是由于核壳状结构的形成.腐蚀实验结果表明,由于富Cr的a′相的析出,导致贫Cr区的形成,进而降低了马氏体时效不锈钢的耐蚀性能.
The segregation characteristics of elements in a multi-phase strengthened martensitic stainless steel aged by aging and its relationship with material mechanics and corrosion resistance were studied by high resolution transmission electron microscopy (HRTEM) and atomic probe tomography (APT) The results show that martensitic stainless steel precipitates three kinds of strengthening phases during aging: Mo-rich R ’phase, Ni3Ti intermetallic compound h phase and Cr-rich a’ phase, in which R ’phase and h phase With the formation of a core-shell structure, a ’phase is dispersed separately in the matrix.After the aging time is extended to 40 h, the main strengthening phase h composition, the number density and the equivalent radius of the basic stability, while martensite aging stainless steel The strength is no longer significant changes in this excellent anti-over-effectiveness due to the formation of the core-shell structure.The results of corrosion experiments show that due to the precipitation of Cr-rich a ’phase, leading to the formation of depleted Cr region, thereby reducing the Corrosion resistance of martensitic stainless steel.