Quantitative evaluation of 3D surface roughness parameters during cavitation exposure of 16Cr–5Ni hydro turbine steel
Quantitative evaluation of 3D surface roughness parameters during cavitation exposure of 16Cr–5Ni hydro turbine steel
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DOI：
10.1016/j.wear.2014.07.015
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发表时间：
2014-12
期刊：
影响因子：
5
通讯作者：
R. K. Kumar;S. Seetharamu;M. Kamaraj
中科院分区：
文献类型：
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作者：
R. K. Kumar;S. Seetharamu;M. Kamaraj
根据ASTM G32标准的指导方针，在振动空化试验台上对16Cr-5Ni级马氏体不锈钢的抗空化侵蚀性能进行了长达35小时的长时间评估。用x射线衍射法观察了空化初期残余奥氏体含量的变化。分析了不同空化暴露后的表面形貌特征和定量三维表面纹理参数的演变。利用激光共聚焦扫描显微镜，分析了平均表面粗糙度偏差（Sa）、标准差粗糙度（Sq）、平均粗糙度深度（Sz）和表面偏度（Ssk）随空化时间的变化，以及相应的二维线粗糙度参数Ra、Rq、Rz和Rsk，以识别钢的损伤机制。研究了空化过程中空化面积和空化体积的变化率。根据金属损失率确定了空化侵蚀的孕育、加速和稳定三个阶段。在这三个阶段中，粗糙度曲线的变化与其各自的材料损失率之间存在相关性。利用三维表面参数是监测大型构件空化损伤过程的重要工具。
The cavitation erosion resistance of 16Cr–5Ni grade martensitic stainless steel was evaluated for long periods of up to 35 h in a vibratory cavitation test rig as per the guidelines of the ASTM G32 standard. The change in retained austenite content during the initial period of cavitation was monitored by x-ray diffractometry. The evolution of surface topography features and quantitative 3D surface texture parameters were analyzed after different cavitation exposures. The average surface roughness deviations (Sa), standard deviation roughness (Sq), mean roughness depth (Sz) and surface skewness (Ssk) with cavitation time and the corresponding 2D line roughness parameters Ra, Rq, Rz, and Rsk were evaluated using a confocal laser scanning microscope to identify the damage mechanisms in the steel. Also, the rate of change of the surface area and the cavitated volume during cavitation were studied. Three stages of cavitation erosion, such as incubation, acceleration and steady erosion rate based on metal loss rate were determined. A correlation was observed between the change in roughness profiles during the three stages and their respective rates of material loss. The use of 3D surface parameters is an important tool for monitoring progress of cavitation damage in large-sized components.