渗氮温度对Inconel 718合金磨损和腐蚀性能的影响

Effect of nitriding temperature on the wear and corrosion behavior of the Inconel 718 alloy

研究不同渗氮温度下QPQ处理对Inconel 718合金的耐磨性和防腐性能的影响。Inconel 718合金试样块采用QPQ复合盐浴处理技术,分别在590℃,620℃和650℃的渗氮温度下进行渗氮处理5 h,然后均在400℃氧化30 min。利用摩擦磨损试验、电化学、X射线衍射仪、金相显微镜和显微维氏硬度计系统地研究了经不同渗氮温度下处理后改性表面层的相组成和性能特点。结果显示改性表面的微观结构和相组成与渗氮温度有关。随着渗氮温度的提高,不同厚度的渗氮层形成,经处理后的Inconel 718合金的耐磨性得到极大的提高,且其显微硬度比未处理的大三倍。然而,由于Cr N的形成造成了在表面渗氮层固溶体中Cr含量的减少,导致Inconel 718合金的耐腐蚀性较未处理的腐蚀性低。

The influence of nitriding temperature on the wear and corrosion of Inconel 718 precipitation strengthening nickel based superalloy was investigated. Nitriding treatment of Inconel 718 was carried out at 590 ℃,620 ℃ and 650 ℃ for 5 h respectively by Quench-PolishQuench complex salt bath heat treatment（ QPQ） process,followed by the same oxidation process with heating at 400 ℃ for 30 min.Characterization of the properties of modified surface layer was systematically evaluated by ball-on-disc wear tester, electrochemical polarization methods,X-ray diffraction,optical microscopy（ OM） and microhardness tester. The experimental results obtained revealed that the microstructure and phase constitutes of the nitrided surface was related to the nitriding temperature conditions. Different nitriding layers were formed as the nitriding temperature got increase. The process not only significantly improved the anti-wear property of Inconel 718,but also extremely enhanced its microhardness,which was almost three times higher than that of untreated sample. However,due to the formation of Cr N and the depletion of Cr in the solid solution of the nitriding layer,the corrosion resistance of treated samples got reduced.