AuNi钎料真空钎焊GH4169高温合金接头的组织及性能

Microstructure and mechanical properties of GH4169 superalloy vaccum brazed joints with AuNi brazing filler metal

  • 摘要:
    目的 旨在研究AuNi钎料钎焊GH4169接头的组织和性能。
    方法 利用金基钎料BAu82Ni950在1 000 ℃/20 min规范下对GH4169进行真空钎焊,然后对钎焊接头进行焊后热处理,对比研究钎焊接头经过固溶、双级时效后的组织演变。
    结果 结果发现,利用AuNi钎料钎焊的GH4169接头中未生成金属间化合物;靠近GH4169母材,经过钎料与母材之间的互扩散,形成了(Au,Ni)固溶体相的扩散区,接头中央为剩余AuNi钎料区。经过980 ℃/15 min的固溶处理,界面附近的扩散区完全均质化,但中央钎料区仍有球形相残余;而经过双级时效后,圆球形相略有长大,由于组织的遗传性而趋同于钎焊态组织。经过焊后热处理,接头平均室温抗拉强度由829.5 MPa提高至996 MPa,但接头650 ℃的高温抗拉强度下降至不足室温强度的一半。
    结论 焊后热处理可有效细化组织,显著提高接头性能;而接头650 ℃高温强度下降明显主要归因于AuNi钎料的耐高温性不足。

     

    Abstract: Objective The aim is to study microstructure and mechanical properties of GH4169 superalloy brazed joints with AuNi brazing filler metal. Methods GH4169 superalloy was brazed with BAu82Ni950 brazing filler metal at 1 000 ℃ for 20 min, and then brazed joints were subjected to post-brazing heat treatment. Microstructure evolution of brazed joints after solid solution and two-stage aging treatment was compared and studied. Results The results show that no intermetallic compounds are formed in GH4169 brazed joints with AuNi brazing filler metal. Closed to GH4169 base material, diffusion zone of (Au,Ni) solid solution phase forms by mutual diffusion between brazing filler metal and base material. And the central part of brazed joints is mainly the residual AuNi brazing filler metal. After solid solution treatment at 980 ℃ for 15 min, diffusion zone near the interface is completely homogenized, but there is still spherical phase in the central part of brazed joints. After two-stage aging treatment, spherical phase grows up slightly and has convergence to brazed microstructure due to structure inheritance. After post-brazing heat treatment, average tensile strength of brazed joints at room temperature is increased from 829.5 MPa to 996 MPa, but tensile strength of brazed joints at 650 ℃ is decreased to less than half of that at room temperature. Conclusion Post-brazing heat treatment can effectively refine microstructure and significantly improve performance of brazed joints, while the main reason for the significant decrease in high-temperature strength of joints at 650 ℃ is attributed to insufficient high-temperature resistance of AuNi brazing filler metal.

     

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