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载荷对Fe-Cr-C-Nb堆焊合金松散磨粒磨损行为的影响

Effects of load on loosing abrasive wear behavior of Fe-Cr-C-Nb hardfacing alloys

  • 摘要: 采用熔化极气体保护焊技术(gas metal arc welding,GMAW)制备了Fe-Cr-C-Nb堆焊合金,对合金在不同法向载荷(70~190 N)下进行干砂/橡胶轮松散三体磨粒磨损实验。通过X射线衍射分析、扫描电子显微镜观察、能谱分析、磨损失重测试、体视显微镜观察、激光扫描共焦显微镜观察和维氏硬度测量等手段表征了合金显微组织与磨痕特征,研究了合金在不同法向载荷作用下磨损行为的变化。结果表明:堆焊合金显微组织主要由初生奥氏体基体、网状共晶组织及分布于基体上的NbC硬质相组成;合金磨损损失、磨痕深度随法向载荷增大而增大,磨损机制主要为奥氏体基体的微切削及NbC、M7C3的脆性剥落;法向载荷的提高加剧了磨痕亚表面的加工硬化,从而提高了奥氏体基体耐磨性,这导致磨损损失及磨痕深度增长幅度缓慢。

     

    Abstract: Fe-Cr-C-Nb hardfacing alloys were prepared by gas metal arc welding (GMAW) method. Loosing abrasive wear tests of dry sand/rubber wheel were carried out on Fe-Cr-C-Nb alloys at different normal loads (70~190 N). Microstructures and wear scar characteristics of alloy were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy disperse spectroscopy (EDS), weight loss test, stereo microscopy, laser scanning confocal microscopy (LSCM), and Vickers-hardness test to investigate the abrasive wear behavior of alloy in various normal loads. The results show that, the microstructures of Fe-Cr-C-Nb hardfacing alloys are mainly composed of primary austenite matrix, reticular eutectic structure, and NbC hard phase distributed on the matrix. The wear loss and wear scar depth increase with the increase of normal load. The wear mechanism is mainly composed of the micro-cutting of austenite matrix and the brittle flaking of NbC and M7C3. The increase of normal load aggravates the machining hardening of wear scar subsurface, thus improving the wear resistance of austenite matrix and leading to the slow increase of wear loss and wear scar depth.

     

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