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淬火处理过程中的局部干涉对FGH96合金表面组织的影响

Effect of local interference on the surface microstructure of FGH96 alloys in quenching process

  • 摘要: 采用光学显微镜(optical microscope,OM)、扫描电子显微镜(scanning electron microscope,SEM)、电子探针(electron probe microanalysis,EMPA)、显微硬度计和数值模拟等手段,研究了淬火处理过程中的局部干涉(淬火夹具)对FGH96合金表面组织的影响。结果表明,淬火处理用夹具对热态FGH96合金表面产生激冷作用,改变了接触点位置合金的冷却方式,进而改变了γ′相的析出和长大行为。经低倍腐蚀后,不同尺寸和形貌的γ′相出现了视觉上的色差,宏观上表现为腐蚀圈的形成。腐蚀圈的最大直径为~10 mm,截面深度为~3 mm;腐蚀圈内二次γ′相呈细小球状分布,平均尺寸为~100 nm;腐蚀圈上二次γ′相呈多边形分布,平均尺寸为~350 nm;圈外二次γ′相呈球状分布,平均尺寸为~150 nm。二次γ′相的尺寸和形貌的差异导致腐蚀圈内外显微硬度的波动,圈外显微硬度平均为~HV 450,圈内达到了~HV 485。除此之外,腐蚀圈附近区域无晶粒组织差异,无元素偏析情况。

     

    Abstract: Effect of local interference (holding devices) on the surface microstructure of FGH96 alloys in quenching process was studied by optical microscope (OM), scanning electron microscope (SEM), electron probe microanalysis (EPMA), microhardness, and numerical simulation. The results show that, the holding devices used in quenching produce the chilling effect at the surface of FGH96 alloys, which changes the cooling mode of the connect points and then affects the precipitation and growth behavior of γ′ phases. After the low corrosion, the γ′ phases with the different size and morphology exhibit the visual color difference, leading to the corrosion circles. The maximum diameter of corrosion circles is ~10 mm, and the section depth is ~3 mm. The secondary γ′ phases inside the corrosion circles are fine and spherical, and the average size is ~100 nm. The secondary γ′ phases on the corrosion circles are polygonal distributed, and the average size is ~350 nm. The secondary γ′ phases outside the circles are spherical in distribution, and the average size is ~150 nm. The different size and morphology of the secondary γ′ phases result in the fluctuation of microhardness inside and outside the corrosion circles. The average microhardness is ~HV 450 outside the circles, and that of ~HV 485 inside the circles. The grain structure difference and the element segregation near the corrosion circles are not found.

     

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