一种镍基单晶高温合金TLP接头的微观组织和性能研究
发布时间：2019-05-15 18:05
【摘要】：镍基单晶高温合金具有优异的高温力学性能,瞬态液相(Transient liquid phase,简称TLP)连接方法是一种适于难以熔焊的高温合金的连接技术。本文分别选用Ni-Cr-B和Ni-Cr-Si两种合金粉末作为中间层合金对一种镍基单晶高温合金进行TLP连接,研究了连接温度和时间对接头的组织和成分分布的影响,分析了TLP连接过程的等温凝固行为,测试了接头的硬度和剪切性能。Ni-Cr-B中间层合金TLP连接的接头分为三个典型的区域:接头中心的共晶区、位于共晶区两侧的等温凝固区和位于近焊缝处基体中的扩散影响区。在接头中心的共晶区上形成Cr2B+γ和Ni3B+γ两种共晶;等温凝固区为γ镍基固溶体;在扩散区上形成M3B2析出相。随连接温度的升高或连接时间的延长,共晶区上的硼化物相逐渐减少,共晶区逐渐变窄;等温凝固界面由接头两侧向中心生长,等温凝固区逐渐变宽;扩散影响区的硼化物析出相继续长大并向基体内扩散。为避免初熔现象的产生,TLP连接温度和保温时间应在初熔转变界线以下的条件选择。TLP接头在连接时间为2h时,随连接温度的升高接头中心的硬度明显降低;在连接温度为1200℃时,TLP接头随连接时间的延长接头中心硬度略有降低。升高连接温度或延长连接时间有助于提升接头的剪切强度,增加接头的断裂韧性,在1170℃保温30min的条件下TLP接头为脆性解理断裂。Ni-Cr-Si中间层合金TLP连接的接头由两个区域组成:共晶区和等温凝固区,接头中心共晶区上是Ni16Cr6Si7+γ和(Cr,Si)3Ni2Si+γ共晶,而等温凝固区是含Si的镍基固溶体。随连接时间的延长或连接温度的升高,共晶区宽度越窄,等温凝固区宽度越宽,等温凝固进行的越充分。为避免初熔现象的产生,TLP连接温度和保温时间应在初熔转变界线以下的条件选择。TLP接头在连接时间为2h时,随连接温度升高接头中心的硬度明显降低;在1170℃下,TLP接头随连接时间增加接头中心硬度略有降低。升高连接温度或延长连接时间有助于提升接头的剪切强度,增加接头的断裂韧性。在1170℃保温30min的条件下TLP接头为微孔聚集型韧性断裂。
[Abstract]:Nickel-based single crystal superalloy has excellent high temperature mechanical properties. Transient liquid phase (Transient liquid phase, (TLP) bonding method is a kind of bonding technology suitable for difficult fusion welding of superalloy. In this paper, Ni-Cr-B and Ni-Cr-Si were used as interlayer alloys for TLP bonding of a nickel-based single crystal superalloy. The effects of bonding temperature and time on the microstructure and composition distribution of the joints were studied. The isothermal solidification behavior of TLP bonding process was analyzed, and the hardness and shear properties of the joints were tested. The joints connected by Ni-Cr-B interlayer alloy TLP are divided into three typical regions: the eutectic region in the center of the joint. The Isothermal solidification zone is located on both sides of the eutectic region and the diffusion affected zone is located in the matrix near the weld. Two kinds of eutectic, Cr2B 纬 and Ni3B 纬, were formed in the eutectic region of the joint center, and the M3B2 precipitated phase was formed in the isothermal solidification region of the solid solution based on gamma nickel and the precipitated phase of M3B2 in the diffusion zone. With the increase of bonding temperature or the prolongation of bonding time, the boride phase on the eutectic region decreases and the eutectic region narrows gradually, and the Isothermal solidification interface grows from both sides of the joint to the center, and the Isothermal solidification zone widens gradually. The precipitated phase in the diffusion affected region continues to grow and diffuses into the matrix. In order to avoid the phenomenon of initial melting, the connection temperature and holding time of TLP should be selected below the initial melting transition line. When the connection time is 2 h, the hardness of the joint center decreases obviously with the increase of connection temperature. When the connection temperature is 1200 鈩，
本文编号：2477693
[Abstract]:Nickel-based single crystal superalloy has excellent high temperature mechanical properties. Transient liquid phase (Transient liquid phase, (TLP) bonding method is a kind of bonding technology suitable for difficult fusion welding of superalloy. In this paper, Ni-Cr-B and Ni-Cr-Si were used as interlayer alloys for TLP bonding of a nickel-based single crystal superalloy. The effects of bonding temperature and time on the microstructure and composition distribution of the joints were studied. The isothermal solidification behavior of TLP bonding process was analyzed, and the hardness and shear properties of the joints were tested. The joints connected by Ni-Cr-B interlayer alloy TLP are divided into three typical regions: the eutectic region in the center of the joint. The Isothermal solidification zone is located on both sides of the eutectic region and the diffusion affected zone is located in the matrix near the weld. Two kinds of eutectic, Cr2B 纬 and Ni3B 纬, were formed in the eutectic region of the joint center, and the M3B2 precipitated phase was formed in the isothermal solidification region of the solid solution based on gamma nickel and the precipitated phase of M3B2 in the diffusion zone. With the increase of bonding temperature or the prolongation of bonding time, the boride phase on the eutectic region decreases and the eutectic region narrows gradually, and the Isothermal solidification interface grows from both sides of the joint to the center, and the Isothermal solidification zone widens gradually. The precipitated phase in the diffusion affected region continues to grow and diffuses into the matrix. In order to avoid the phenomenon of initial melting, the connection temperature and holding time of TLP should be selected below the initial melting transition line. When the connection time is 2 h, the hardness of the joint center decreases obviously with the increase of connection temperature. When the connection temperature is 1200 鈩，
本文编号：2477693
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