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FSX-414钴基高温合金已应用于制造燃气涡轮机一级喷嘴,当燃气涡轮机运行时,其第一级喷嘴处于低周疲劳状态,这样的作业条件使喷嘴等部件开裂。通常选用钴基合金采用钨极电弧焊接(TIG)技术对喷嘴上的裂纹进行焊接。研究TIG对FSX-414钴基高温合金在950°C时拉伸及低周疲劳性能的影响。在应变速率为3.3×10~(-4) s~(-1)、应变率R为-1(R=ε_(min)/ε_(max))、总应变变化值?ε_t为0.8%~2%的条件下研究FSX-414合金的低周疲劳性能。实验结果表明:焊接和非焊接样品的屈服应力和最大拉伸应力相近,但焊接样品的韧性比非焊接样品的低。对于焊接试样,在高应变条件下,焊缝区发生裂纹的成核和扩展。但当?ε_t=0.8%时,在非焊接试样的相同区域发生断裂。上述结果表明,焊接试样的总疲劳寿命低于非焊接试样的总疲劳寿命。此外,在所进行的低周疲劳实验中均观察到了软化现象。
The FSX-414 cobalt base superalloy has been used in the manufacture of gas turbine primary nozzles. When the gas turbine is in operation, the first stage nozzles are in a low cycle fatigue condition, cracking the nozzles and other components under such operating conditions. Cobalt-based alloys are commonly used for welding the cracks on the nozzle using Tungsten arc welding (TIG). The effect of TIG on tensile and low cycle fatigue behavior of FSX-414 cobalt base superalloy at 950 ° C was investigated. The strain rate R is -1 (R = ε min / ε max) at a strain rate of 3.3 × 10 -4 s -1, and the total strain change εε is 0.8% -2 % Of the low-cycle fatigue properties of FSX-414 alloy. The experimental results show that the yield stress and the maximum tensile stress of welded and non-welded samples are similar, but the toughness of welded samples is lower than that of non-welded samples. For the welded specimens, nucleation and propagation of cracks occurred in the weld zone under high strain conditions. However, when ε_t = 0.8%, fractures occurred in the same area of the non-welded specimen. The above results show that the total fatigue life of welded specimens is lower than the total fatigue life of non-welded specimens. In addition, softening was observed in the low-cycle fatigue tests conducted.