熔体过热处理对镍基高温合金组织与力学性能的影响

发布时间：2018-02-12 19:21

  本文关键词： 熔体过热处理 GH4169 K418 F418 组织 力学性能　出处：《兰州理工大学》2016年硕士论文　论文类型：学位论文

【摘要】：熔体过热处理影响合金的显微结构,进而影响合金的力学性能。因此,本文选用X射线衍射仪、扫描电子显微镜和电子万能试验机等,对熔体过热处理后GH4169、K418、返回料F418合金的显微组织和力学性能的变化规律进行了研究,结果如下:熔体过热处理后的GH4169合金,枝晶间Laves相、共晶γ+Laves和MC碳化物析出数量减少,分布均匀;Nb、Mo元素的偏析程度显著降低;合金的室温综合力学性能提高。当感应加热功率为3.7KW时,抗拉强度有最大值721MPa,约是过热处理前的1.5倍。合金热处理后,析出γ″和脆性δ相,随着熔体过热温度的升高,δ相溶解。当感应加热功率4.5KW时,合金的抗拉强度有最大值1079MPa,比热处理前提高35.2%,同比,延伸率提高16.7%。K418合金经固溶+时效热处理后,随着固溶温度的逐渐升高,晶界上的碳化物由骨架状向链状转变,γ′由不规则的棒状向规则的立方形转变,尺寸减小。存在最佳热处理制度:1180℃×2h(AC)+930℃×16h(AC),合金的抗拉强度、延伸率和断面收缩率均有最大值,分别为:821MPa、6.0%和5.7%。试样断口中心分布着枝晶林,沿二次枝晶根部断裂,断口外沿出现撕裂棱和韧窝,韧窝尺寸越小越密集,合金塑性越好。熔体过热处理后的K418合金,γ′形貌变化不大,呈立方状和不规则块状,MC碳化物由汉字骨架型转变为链状。合金的室温综合力学性能降低。当感应加热功率为44.5KW时,综合力学性能最差,与过热处理前相比,强度、延伸率和硬度分别降低约24%、50.9%和5.5%。热处理后,初生碳化物MC与γ固溶体发生反应,生成γ′和细小粒状或片状的M6C/M23C6。当感应加热功率为40KW时,与热处理前相比,合金的强度、延伸率和硬度分别降低约18.1%、43.4%和10.7%。复合熔盐净化+熔体过热处理返回料F418合金后,γ′相尺寸增加,C、S、N元素含量降低,硬度降低。存在最佳过热温度1480℃,C、S、O、N元素含量均降低,与合金原始试样成分相比,分别降低约51.9%、76.9%、5.6%和75.4%,同比,硬度降低约10.9%。
[Abstract]:The melt superheat treatment affects the microstructure of the alloy and then the mechanical properties of the alloy. Therefore, X-ray diffractometer, scanning electron microscope and electronic universal testing machine are used in this paper. The changes of microstructure and mechanical properties of F418 alloy after melt superheat treatment were studied. The results are as follows: the amount of precipitation of GH4169 alloy, interdendritic Laves phase, eutectic 纬 Laves and MC carbide after melt superheat treatment is reduced. The segregation degree of NbCMo element decreased significantly, and the comprehensive mechanical properties of the alloy at room temperature increased. When the induction heating power was 3.7 KW, the tensile strength reached a maximum value of 721 MPA, which was about 1.5 times that of that before superheat treatment. After heat treatment, the tensile strength of the alloy was 1.5 times that of that before superheat treatment. 纬 "and brittle 未 phase are precipitated, and the 未 phase dissolves with the increase of melt superheating temperature. When the induction heating power is 4.5 KW, the tensile strength of the alloy has a maximum value of 1079 MPA, which is 35.2% higher than that before heat treatment. With the increasing of the solution temperature, the carbides on grain boundaries change from skeleton to chain, 纬 'from irregular rod to regular square, and the size decreases. There is the best heat treatment system: 1: 1180 鈩，

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