35CrMo钢罐装法多段渗氮渗层组织与耐蚀性能

为确定合理的多段渗氮工艺,以尿素为渗氮剂,采用密封罐法对35CrMo钢进行多段渗氮处理,并利用金相显微镜、X射线衍射仪、显微硬度计和化学工作站研究了由不同阶段渗氮工艺制备的氮化层的显微组织、显微硬度和耐蚀性能。结果表明:采用三段渗氮工艺(520℃×3 h+600℃×2 h+520℃×1 h)制备的渗氮层最厚,其氮化层组织主要由Fe-Cr相和Fe3N相组成,表面硬度较高,耐蚀性最好。该三段渗氮工艺符合氮化规律,增加了渗氮层厚度,提高了硬度和耐蚀性能。

Microstructure and corrosion resisting property of nitration case of 35CrMo steel multiple-stage nitriding using seal pot method

This paper introduces the multiple-stage nitriding treatment of 35CrMo steel by seal pot method and using the ureabromin as the nitriding agent and investigation into the microstructure, the microhardness and the corrosion-resisting property of the nitriding layer by the optical microscope, X-ray diffractermeter and the microhardness tester as well as electrochemical workstation so as to determine the appropriate multiple-stage nitriding process. The results show that the use of three-stage nitriding process （520 ℃ ×3 h ＋ 600 ℃2 ×2 h ＋ 520 ℃ × 1 h） affords a nitriding layer which boasts a maximum thickness, consists mainly of Fe-Cr and Fe3N phase, and demonstrates the greater microhardness and the best corrosion-resisting property. It follows that three-stage nitriding process up to the nitration rules, enables an increased thickness of the nitration case and an improved microhardess and corrosion resistance property.