FeCrBSiWNb喷涂层的钨极氩弧摆动重熔处理

TIG Weaving Remelting of FeCrBSiWNb Coating by HVAS

目的设计一种新型的FeCrBSiWNb高速电弧喷涂涂层的钨极氩弧摆动重熔工艺,解决传统钨极氩弧无摆动重熔层单道宽度窄且不均匀、多道搭接处易出现气孔及裂纹等问题。方法通过几何分析和计算设计摆动重熔工艺,并制备FeCrBSiWNb重熔层,利用XRD衍射仪、光学显微镜、扫描电镜对摆动重熔层的相结构、显微组织进行表征,用显微硬度仪对其纵截面的显微硬度进行测量。结果设计的钨极氩弧摆动重熔工艺参数:电流53~55A,钨极移动在X方向移动速度65~68mm/min,Y方向移动速度485~500mm/min。摆动重熔层内部无裂纹且单道宽度增大,FeCrBSiWNb重熔层的基体组织由马氏体、残余奥氏体、Fe-Cr固溶体组成,硬质相由硼化物及拉弗斯相组成,重熔层存在固溶强化、析出强化等多种强化方式。重熔层、热影响区、母材的显微硬度分别是820HV0.3、563HV0.3、242HV0.3。结论所设计的新型摆动重熔工艺增大了单道重熔层宽度,进而有效解决了重熔层内部残余应力大易导致裂纹产生的问题。

The work aims to overcome narrow and inhomogeneous single pass, pores and cracks in the multi-track zone of traditional TIG linear remelted coating by designing a novel tungsten inert gas arc （TIG） weaving remelting process for FeCrBSiWNb coating by high velocity arc spraying （HVAS）. The weaving remelting process was designed by geometric analy-sis and calculation, and FeCrBSiWNb remelted coating was prepared. Phase structure and microstructure of the weaving re-melted coating were characterized with X-ray diffractometer （XRD）, optical microscope （OM） and scanning electron micro-scope （SEM）. Microhardness of its cross-section was measured with microhardness tester. Designed remelting process parame-ters： current 53~55 A, X-direction travelling speed 65~68 mm/min and Y-direction travelling speed 485~500 mm/min. The weaving remelted coating was free from crack, and single path width increased. The matrix structure of FeCrBSiWNb remelted coating was mainly composed of martensite, retained austenite and Fe-Cr solid solution. The hard-phase was composed of bo-ride and Laves phase. Various strengthening methods, such as solid-solution strengthening and precipitation hardening, were present in the remelted coating. Microhardness of the remelted coating, heat affected zone （HAZ） and base metal was 820HV0.3, 563HV0.3 and 242HV0.3, respectively. Width of single pass remelted coating is increased by the novel weaving remelting process. And problems such as high residual stress in the coating, which may cause cracks, are effectively solved.