38CrMoAl液压柱塞无白亮层低温离子渗氮工艺研究

Lower Temperature Plasma Nitriding without White Layer for 38CrMoAl Hydraulic Plunger

对38Cr Mo Al液压柱塞进行低温离子渗氮,研究不形成白亮层的工艺条件。采用金相显微镜、X射线衍射仪、显微硬度计、摩擦磨损试验机对处理后的38Cr Mo Al钢显微组织、截面硬度、渗层脆性、耐磨性进行了分析。研究结果表明,相比于510℃常规离子渗氮工艺,38Cr Mo Al钢经450℃低温离子渗氮工艺处理后无白亮层产生,X射线衍射分析表明表层无γ'-Fe4N相生成。同时,38Cr Mo Al钢经450℃低温离子渗氮工艺处理后,不仅截面硬度满足使用要求,而且渗层脆性显著降低,压痕周围均无裂纹产生。耐磨性研究表明,在较大载荷下,450℃低温离子渗氮后耐磨性比510℃常规离子渗氮好。

Lower temperature plasma nitriding is conducted for 38 Cr Mo Al hydraulic plunger in this research. Optical microscopy（OM）,X-ray diffraction（XRD） and micro-hardness and wear tester are used to investigate the microstructure,surface hardness,brittleness of modified layer and wear resistance. The results show that no white bright layer is formed while plasma nitriding at 450 ℃ for 6 h,and XRD also confirm that there existed no γ＇-Fe4 N phase. Meanwhile,the brittleness is decreased at lower temperature plasma nitriding comparing with conventional plasma nitriding,there existed no crack around the indentation for samples plasma nitriding at 450 ℃. Meanwhile,the wear resistance of samples plasma nitrided at 450 ℃ is higher than that of the conventional plasma nitrided samples and meet the requirements.