微量元素Zr对高温合金铸件凝固缺陷及持久性能的影响

Influences of minor alloying element Zr on the casting defects and stress-rupture properties in nickel-based superalloy castings

高温合金中微量元素含量虽然极低,但是其对合金的高温性能产生的重要作用不可忽略。以Zr为例,其存在对高温合金铸造特性和高温力学性能的影响仍需要进一步探索。研究了微量合金元素Zr对K417合金凝固过程中凝固缺陷的形成、组织演变以及持久性能的影响。研究结果表明,Zr的加入会影响合金铸态组织中共晶组织的含量,同时也影响凝固过程中的固液相线。随着Zr含量的增加,凝固温度区间先下降后增加;从而影响合金铸造流动性以及组织凝固缺陷的形成。900℃、314 MPa下的持久性能测试结果表明,随着Zr含量的增加,寿命先延长后降低,Zr含量为0.07%时达到最大值。为铸造高温合金母合金中微量元素含量的控制,提高铸件冶金质量提供实验支撑。

Although the content of minor alloying elements in superalloys is extremely low,their influences on the high-temperature performance of the alloys cannot be ignored.Taking Zr element as an example,its effects on the casting characteristics and high-temperature mechanical properties in superalloys still need further explorations.This study investigated the influence of the trace alloying element Zr on the formation of solidification defects during the solidification process,microstructural evolution,and stress-rupture life of K417 superalloy.The results indicate that the addition of Zr affects the content of eutectic structure in the as-cast microstructure of the alloy,as well as influencing the solidus and liquidus lines during the solidification process.With the increase of Zr content,the solidification temperature range initially decreases and then increases,thereby affecting the casting fluidity of the alloy and the formation of microstructural defects during solidification.The results of the stress-rupture tests at the condition of 900℃and 314 MPa indicate that,with increasing Zr content,the lifespan initially increases and then decreases,reaching the maximum value at the Zr content of 0.07%.Experimental support is provided for controlling the content of trace elements in the master alloy of cast high-temperature alloys and improving the metallurgical quality of castings.