B、P对超超临界燃煤发电机组汽轮机用高温合金GH2107组织和性能的影响

EFFECTS OF B AND P ON MICROSTRUCTURE AND MECHANICAL PROPERTIES OF A-USC GH2107 SUPERALLOY

摘要:

研究了B、P对一种新型700℃超超临界燃煤发电汽轮机用镍铁基变形高温合金GH2107微观组织及力学性能的影响。结果表明：合金中的析出相主要为γ′相、M3B2硼化物、MC和M23C6碳化物。B抑制合金中M23C6的析出和长大，阻止晶界粗化，并通过提高晶界结合力和阻碍晶间裂纹萌生来强化合金。P促进M23C6析出和长大，助长晶界粗化，但是P能抑制裂纹在试样表面萌生和扩展，P原子团还会阻碍晶界滑动与位错滑移。室温下，B、P对晶界的强化作用较弱，晶界为薄弱区，而在高温下，B、P对晶界起到了很好的强化作用。当B含量过高时，将与P产生竞争偏析，降低合金的拉伸强度和持久寿命。

关键词:700℃超超临界; 镍铁基高温合金; B和P; 微观组织; 力学性能

Abstract:

A new Ni-Fe based wrought superalloy for 700℃ advanced ultra-supercritical steam turbine rotor application was developed. The effects of B and P on the microstructure and mechanical properties of the alloy were investigated. The results show that the major precipitates in the alloy were γ′, MC, M23C6 and M3B2. B restrains the precipitation and growth of the M23C6, increasing the binding force of grain boundaries and obstacles intergranular crack initiation. P accelerates the precipitation and growth of the M23C6, and suppress crack initiation and propagation in the surface. B and P play an even more significant role in strengthening grain boundaries at 700 ℃ than at room temperature, they improve not only the strength but also the high-temperature ductility of the alloy. But However, high B content impairs the beneficial effect of P element. reducing the tensile strength and rupture life of the alloy.

Key words:700℃ advanced ultra-supercritical; Ni-Fe base superalloy; B (Boron) and P (Phosphorus); Microstructure; Mechanical property