Nitriding behavior and corrosion properties of AISI 304L and 316L austenitic stainless steel with deformation-induced martensite
Nitriding behavior and corrosion properties of AISI 304L and 316L austenitic stainless steel with deformation-induced martensite
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DOI：
10.1016/j.surfcoat.2017.05.059
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发表时间：
2017-09
影响因子：
5.4
通讯作者：
J. Biehler;H. Hoche;M. Oechsner
中科院分区：
文献类型：
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作者：
J. Biehler;H. Hoche;M. Oechsner
AISI 304L 和 AISI 316L 是亚稳态奥氏体不锈钢，由于其铬含量而表现出良好的耐腐蚀性，但机械性能较差，因此耐磨性较差。通过冷轧或喷丸形成形变诱发马氏体，获得轻微的硬化效果。由于所谓的 S 相（氮扩散区）的形成，通过等离子渗氮工艺可以获得相当大的表面硬度。在工业制造过程中，冷变形是不可避免的，并且没有进行最终退火来消除变形诱发的马氏体。因此，了解氮化过程中微观结构的行为以及由此产生的性能至关重要。如果在低于临界温度下进行等离子渗氮，S相也被认为可以提高耐腐蚀性。高于此温度，氮化铬会在基体中析出，降低耐腐蚀性。在这项研究中，AISI 304L 和 AISI 316L 进行固溶退火，然后进行加工硬化，冷轧度为 38%。表面分别经过抛光和喷丸处理。变形诱导马氏体的量取决于材料，这反过来又影响氮化行为。结果表明，高度变形的微观结构促进了 S 相的生长。此外，检查了所得的表面硬度和在盐溶液中的耐腐蚀性。腐蚀特性很大程度上取决于表面形貌。喷丸处理会增加粗糙度，还会引起裂纹等伪影，从而加速腐蚀动力学。对结果进行统计评估，得出微观结构、等离子渗氮行为和所得性能之间的相关性。
AISI 304L and AISI 316L are metastable austenitic stainless steels, which exhibit a good corrosion resistance due to their chromium contents but suffer from poor mechanical properties and therefore exhibit poor wear resistance. A slight hardening effect is gained by the formation of deformation-induced martensite either by cold-rolling or shot-peening. A considerable surface hardness could be achieved by plasma nitriding processes due to the formation of the so-called S-phase, the nitrogen diffusion zone. In industrial manufacturing processes cold-deformation could not be avoided and no final annealing is carried out to eliminate the deformation-induced martensite. Therefore, the knowledge about the behavior of the microstructure regarding the nitriding process and the resulting properties is fundamental. The S-phase is also assumed to improve the corrosion resistance if the plasma nitriding is performed below a critical temperature. Above this temperature chromium nitrides precipitate in the matrix and decrease the corrosion resistance.In this study, AISI 304L and AISI 316L were solution annealed and afterwards work hardened with a cold rolling degree of 38%. The surfaces were polished and shot-peened, respectively. The amount of deformation induced martensite depends on the material and this, in turn influences the nitriding behavior. It will be shown, that a highly deformed microstructure promotes the growth of the S-phase. Furthermore, the resulting surface hardness and corrosion resistances in saline solution were examined. The corrosion properties are highly dependent on the surface topography. Shot-peening increases the roughness and also induces crack like artifacts which accelerate corrosion kinetics. The results were evaluated statistically to derive correlations between the microstructure, the plasma nitriding behavior and the resulting properties.