Influence of Shot Peening on the Isothermal Fatigue Behavior of the Gamma Titanium Aluminide Ti-48Al-2Cr-2Nb at 750 °C
Influence of Shot Peening on the Isothermal Fatigue Behavior of the Gamma Titanium Aluminide Ti-48Al-2Cr-2Nb at 750 °C
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DOI：
10.3390/met11071083
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发表时间：
2021-07
期刊：
影响因子：
2.9
通讯作者：
C. Breuner;Stefan Guth;Elias Gall;R. Swadźba;J. Gibmeier;M. Heilmaier
中科院分区：
文献类型：
--
作者：
C. Breuner;Stefan Guth;Elias Gall;R. Swadźba;J. Gibmeier;M. Heilmaier
提高金属材料疲劳寿命和强度的一种可能是喷丸强化。然而，在高温下，诱导的残余应力可能会松弛。为了研究喷丸处理对γ TiAl 48-2-2高温疲劳行为的影响，对喷丸处理和未喷丸处理的TiAl 48-2-2试样在750℃空气中进行了等温疲劳试验。利用EBSD、显微硬度和残余应力分析对喷丸材料进行了表征。喷丸强化导致表面硬度显著提高，表面附近残余压应力高。这两种影响都可能对寿命产生积极影响。然而，它也会导致大块材料的表面缺口和拉伸残余应力，对循环寿命产生负面影响。在应力幅为260 MPa的全反向单轴拉压疲劳试验（R =−1）中，正效应占主导地位，疲劳寿命增加。在较低的应力幅值为230 MPa时，内部拉伸残余应力的负面影响占主导地位，寿命下降。喷丸强化如果表面没有被喷丸破坏，则会导致从表面裂纹到体积裂纹的过渡。
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.