【目的】38CrMoAl钢是液压泵柱塞常用材质之一,其表面性能对液压泵长寿命安全服役尤为重要。磨损是液压泵柱塞的主要失效方式,采用表面强化处理能够突破其性能极限,是实现液压泵高性能、高可靠运行的有效途径。【方法】采用表面织构化和活性屏离子氮化的复合处理工艺对38CrMoAl钢进行表面形性调控,以期实现其表面强化方法。先利用激光加工技术在38CrMoAl钢表面制备凹坑织构,再对38CrMoAl钢和表面织构化38CrMoAl钢进行活性屏离子氮化处理。借助球-盘式摩擦磨损试验机研究表面织构-活性屏离子氮化复合处理对38CrMoAl钢摩擦学行为的影响。【结果】结果表明,38CrMoAl钢表面生成了ε-Fe2-3N、γ'-Fe4N和CrN;氮化层表面致密且无明显裂纹和孔洞;氮化层均匀、连续,由白亮层和扩散层组成。氮化层的截面硬度呈梯度分布,试样表面硬度最高,随着距表面距离的增大,硬度逐渐降低。38CrMoAl钢相关试样与Al2O3球的干滑动摩擦结果可知,38CrMoAl钢的摩擦系数为0.40,而表面织构-活性屏离子氮化38CrMoAl钢的摩擦系数为0.36;经复合处理后,38CrMoAl钢的磨损失重降低了92.5%.复合处理显著提高了38CrMoAl钢的摩擦学性能。

【Purposes】 38CrMoAl steel is often used as pistons in a hydraulic pump, its surface performance is especially important for long-life safe working. Wear is the main failure mode of pistons in a hydraulic pump. With surface strengthening treatment, it is able to break through its performance limit and realize high performance and reliable operation of a hydraulic pump. 【Methods】 In this work, the pattern and performance on the surface of 38CrMoAl steel has been regulated by a duplex treatment of surface texturing (ST) and active screen plasma nitriding (ASPN), aiming to achieve strengthening on its surface. Dimple texture with different shapes were first prepared on 38CrMoAl steel surface by laser processing technology. 38CrMoAl steel samples with and without textured surface have been treated by ASPN. A ball-on-disc friction and wear testing machine was employed to investigate the effect of surface texture-active screen plasma nitriding duplex treatment on the tribological behavior of 38CrMoAl steel. 【Findings】 The results show that ASPN layer is mainly built up by the phases of ε-Fe2-3N, γ'-Fe4N and CrN. The ASPN layer is compact, and free of obvious cracks and holes. Meanwhile, it is found that the uniform and continuous ASPN layer consists of a white bright layer and a diffusion layer. The hardness across surface to the inside of the ASPN layer has demonstrated a gradient distribu- tion, where the highest hardness value is detected on the surface, and the hardness decreases as the distance from the surface increases. According to the dry sliding friction results of 38CrMoAl steel related samples against Al2O3  balls, the coefficients of friction of 38CrMoAl steel and ST+ ASPN-38CrMoAl steel are 0.40 and 0.36, respectively. The ST+ASPN-38CrMoAl steel pres- ents a 92.5% reduction in mass loss, as compared with 38CrMoAl steel. It can be concluded that surface texturing-active screen plasma nitriding duplex treatment endows the working surface of 38CrMoAl steel with enhanced tribological performance.