Effect of aging temperature on microstructure evolution and strengthening behavior of L-PBF 18Ni(300) maraging steel
Effect of aging temperature on microstructure evolution and strengthening behavior of L-PBF 18Ni(300) maraging steel
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DOI：
10.1016/j.addma.2022.103071
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发表时间：
2022-08-04
影响因子：
11
通讯作者：
Qiao, Lijie
中科院分区：
文献类型：
--
作者：
Mei, Xingyuan;Yan, Yu;Qiao, Lijie
研究了18 Ni（300）马氏体时效钢在不同尺度下激光-粉末床熔合（L-PBF）时效组织随时效温度的演变规律。细胞结构的变化，沉淀序列，和奥氏体逆转的重要问题进行了评价。基于屈服强度模型，阐明了每种状态下的主导强化因素。铸态完全马氏体基体由位错胞状组织组成，其屈服强度来源于马氏体板条强化和固溶强化，二者贡献相当。440岁的？C时，细胞壁保持稳定，大量的欧米茄颗粒通过剪切机制显著强化基质.在490？C时，胞壁部分破坏，奥氏体沿板条边界沿着开始逆转。致密分布的1-Ni_3Ti颗粒以Orowan机制产生峰值强度，但同时也可能存在剪切过程。在540？C时，胞壁进一步降解，沿板条状边界和残留胞壁周围形成沿着反转奥氏体。其强度主要由于较宽的颗粒间间距而略有下降，但通过Orowan工艺通过Laves-Fe 2 Mo和1-Ni 3 Ti颗粒仍然保持相当高的强度。少量的逆转变奥氏体对强度的降低作用不大，但显著提高了塑性。
This work investigated the microstructure evolution with aging temperature of laser-powder bed fusion (L-PBF) 18Ni(300) maraging steel at different scales. Important issues of cell structure changes, precipitation sequence, and austenite reversion were evaluated. The dominant strengthening factor in each state was elucidated based on yield strength modeling. The as built fully martensitic matrix consists of dislocation cell structures, and its yield strength comes from the martensite lath and solid solution strengthening with comparable contributions. Aged at 440 ?C, the cell walls kept stable and massive omega particles prominently strengthened matrix by shearing mechanism. At 490 ?C, the cell walls were partially destroyed and austenite reversion just began along the lath boundary. Densely distributed 1-Ni3Ti particles produced the peak strength dominantly by the Orowan mechanism, but the shearing process may also exist meanwhile. At 540 ?C, cell walls further degraded and reverted austenite formed along the lath boundaries and around some retained cell walls. Its strength decreased mildly mainly due to the wider inter-particle spacing, but was still maintained quite high by Laves-Fe2Mo and 1-Ni3Ti particles via the Orowan process. The reverted austenite with limited fraction had a minor role in its strength decrease, but improved ductility significantly.