Investigating the Effects of Boron and Zirconium on the High-Temperature Fatigue Behavior of Nimonic 105 Super Alloy

Subject Areas : Superalloys

Zahra Asghary ¹ , Masumeh Seifollahi ^{2 *} , Maryam Morakabati ³ , Seyed Mahdi Abbasi ⁴

1 - Phd Researcher, Faculty of Material and Manufacturing Technologies, Malek Ashtar University of Technology,Tehran, Iran.
2 - Assistant Professor, Faculty of Material and Manufacturing Technologies, Malek Ashtar University of Technology,Tehran, Iran
3 - Associate professor, Faculty of Material and Manufacturing Technologies, Malek Ashtar University of Technology,Tehran, Iran.
4 - Professor, Faculty of Material and Manufacturing Technologies, Malek Ashtar University of Technology,Tehran, Iran.

Received: 2022-04-10 Accepted : 2023-06-08 Published : 2022-07-01

Keywords: Boron, Zirconium, Fracture surface, Nimonic 105 Super alloy, High-temperature low-cycle fatigue,

Abstract :

This study investigates the low-cycle fatigue of Nimonic105 alloy with boron and zirconium of 0.003-0.013 wt.% and 0.0-0.16 wt.%, respectively at 750 °C. The fatigue test results indicated that the alloy with boron of 0.013 wt.% had the highest fatigue life of 400 cycles, while the base alloy showed the lowest fatigue life of 21 cycles at 2% strain amplitudes. For the alloy with 0.16 wt.% Zr, and the alloy with 0.08 wt.% Zr and 0.006 wt.% B, cyclic-hardening occurred at a constant slope. Then, hardening followed a nonlinear procedure at a reducing rate. Finally, softening and fracture happened. For 0.013 wt.% Zr alloy, however, the diagram reached a stable state or slow cyclic-softening and failed after a relatively short period of cyclic -softening. The Coffin-Manson equations’ parameters verified the increased flexibility due to the addition of B. to be a factor in improving high-temperature LCF strength. The investigation of the samples’ fracture surfaces indicated that the intergranular fracture of the base alloy with the lowest fatigue life became intergranular and transgranular fracture in the alloy with 0.16 ‌wt.% Zr content and the alloy with 0.08 wt.% Zr content and 0.006 wt.% B contents. Also, 0.013 wt.% B alloy with the highest fatigue life showed a completely transgranular fracture.