Abstract Fine particle peening (FPP) is a peening process using fine shots with an average diameter of less than 200 µm. Pairs of twin-disc specimens made of carburized and quenched 18CrNiMo7-6 gear steel were subjected to two different FPP processes and conventional shot peening (CSP) using big shots with an average diameter of 600 µm. Rolling–sliding tribology tests were carried out under oil lubrication, and comparisons of the friction coefficient were made between untreated, FPP-treated, and CSP-treated twin-disc specimens. To characterize the relationship between surface topography and friction coefficient, 3D surface parameters, including root mean square roughness (Sq), skewness (Ssk), kurtosis (Sku), core roughness depth (Sk), reduced peak height (Spk), and reduced valley depth (Svk) were measured before and after tribology tests. A linear regression method was applied to analyze the correlations between the surface parameters and the friction coefficient. It was found that FPP is effective in decreasing the friction coefficient during the lubricated rolling–sliding contact compared to untreated specimens. The friction coefficient has a higher correlation with Ssk and the ratio RSvk, which is defined as the ratio of Svk to the sum of Sk, Spk, and Svk. A lower friction coefficient was obtained when the topography had a more negative Ssk and a higher RSvk in the rolling–sliding condition. However, there was a weak linear correlation between the friction coefficient and surface parameters Sq, Sku, Sk, Spk, and Svk, and the relationship between the trend of friction coefficient and those surface parameters is not obvious.

中文翻译：

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细粒喷丸形成的形貌对降低齿轮钢摩擦系数的贡献

摘要 细颗粒喷丸 (FPP) 是一种使用平均直径小于 200 µm 的细粒喷丸的喷丸工艺。对由渗碳和淬火 18CrNiMo7-6 齿轮钢制成的双盘试样进行了两种不同的 FPP 工艺和使用平均直径为 600 µm 的大丸的常规喷丸 (CSP)。在油润滑下进行滚动滑动摩擦学测试，并比较了未处理、FPP 处理和 CSP 处理的双盘试样之间的摩擦系数。为了表征表面形貌和摩擦系数之间的关系，3D 表面参数，包括均方根粗糙度 (Sq)、偏度 (Ssk)、峰态 (Sku)、核心粗糙度深度 (Sk)、减少的峰高 (Spk) 和减少的在摩擦学测试之前和之后测量谷深度（Svk）。应用线性回归方法分析表面参数与摩擦系数之间的相关性。结果表明，与未处理的试样相比，FPP 可有效降低润滑滚动滑动接触过程中的摩擦系数。摩擦系数与 Ssk 和比值 RSvk 有较高的相关性，RSvk 定义为 Svk 与 Sk、Spk 和 Svk 之和的比值。当地形在滚动滑动条件下具有更负的 Ssk 和更高的 RSvk 时，获得较低的摩擦系数。但摩擦系数与表面参数Sq、Sku、Sk、Spk、Svk之间存在弱线性相关性，摩擦系数的变化趋势与这些表面参数的关系不明显。