Influence of Shot Peening on the Isothermal Fatigue Behavior of the Gamma Titanium Aluminide Ti-48Al-2Cr-2Nb at 750 °C

Metals

Elias Gall¹  Christoph Breuner¹  Stefan Guth¹  Martin Heilmaier¹  Jens Gibmeier¹  Radosław Swadźba² 

[1] Karlsruhe Institute of Technology, IAM-WK Institute for Applied Materials, Engelbert-Arnold-Straße 4, 76131 Karlsruhe, Germany;Łukasiewicz Research Network, Institute for Ferrous Metallurgy, K. Miarki 12-14, 44-100 Gliwice, Poland;

关键词: shot peening;    fatigue;    gamma titanium aluminide;    high temperature;    residual stress;    intermetallic;   

DOI  :  10.3390/met11071083

来源: DOAJ

【 摘 要 】

One possibility to improve the fatigue life and strength of metallic materials is shot peening. However, at elevated temperatures, the induced residual stresses may relax. To investigate the influence of shot peening on high-temperature fatigue behavior, isothermal fatigue tests were conducted on shot-peened and untreated samples of gamma TiAl 48-2-2 at 750 °C in air. The shot-peened material was characterized using EBSD, microhardness, and residual stress analyses. Shot peening leads to a significant increase in surface hardness and high compressive residual stresses near the surface. Both effects may have a positive influence on lifetime. However, it also leads to surface notches and tensile residual stresses in the bulk material with a negative impact on cyclic lifetime. During fully reversed uniaxial tension-compression fatigue tests (R = −1) at a stress amplitude of 260 MPa, the positive effects dominate, and the fatigue lifetime increases. At a lower stress amplitude of 230 MPa, the negative effect of internal tensile residual stresses dominates, and the lifetime decreases. Shot peening leads to a transition from surface to volume crack initiation if the surface is not damaged by the shots.

【 授权许可】

Unknown