Microstructure-based crack formation in tungsten exposed to cyclic transient heating

Wang, Yuanyuan; Wang, Hongzhi; Mi, B; Zhao, Jijun; Zhang, Chi

doi:10.1016/j.jnucmat.2023.154555

Cited by 2 publications

(2 citation statements)

References 65 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…该裂纹网络是在受到瞬态热冲击初期形成的, 其进一步发展仅伴随着裂纹宽度的增加. W表面裂纹损伤除了受加载条件的影响, 很大程度上也取决于微观结构和相关的热机械性能, 如图1 -图3所示. Pintsuk等 [11] 经研究发现, 晶粒尺寸越小, W材料表面裂纹损伤越轻, 起到了细晶强化的作用. Wang等 [12] 以W单块表面热能变化引起的累积塑性应变所估算的位移速率为桥梁, 分别预测了截面成分的等轴晶粒(EG)、梯度晶粒 (GG)和异质晶粒(HG)结构以及成分不同表面晶粒尺寸的晶间裂纹扩展行为, 发现梯度晶粒(GG) 结构对裂纹发展有显著的改善作用.…”

Section: N P R E S Sunclassified

Influence of microstructure on thermal fatigue effect of laminated tungsten based plasma-facing material

Qi,

Ma,

et al. 2024

Acta Phys. Sin.

View full text Add to dashboard Cite

The response of tungsten (W) to thermal shock loading, as the best candidate for Plasma-Facing Materials, is an important issue in the research of future fusion devices. Under thermal loading, thermal irradiation damage, including brittle cracking and fatigue cracking, occurs on the surface of W-PFM. In this paper, a new scheme to suppress the thermal irradiation damage of W-PFM, i.e., the laminated structure W-PFM scheme, is proposed. Thermal fatigue experiments were conducted on laminated structures W composed of W foils with different thicknesses and heat treatment processes using an electron beam device. The samples were subjected to thermal pulses with a power density of 48 MW/m2 for 5000 cycles. The results indicate that the crack damage on the surface of the laminated structure W decreased with the decrease of the thickness of W foils under the same heat treatment conditions. The main cracks produced on the surface of laminated structure W after cyclic thermal loading were all approximately parallel to the foil thickness direction. The surface of W foils with smaller thicknesses has only main cracks, while the surface of W foils with larger thicknesses develops crack networks in addition to the main cracks, and the width of the main cracks is larger. For the same thickness, the laminated structure W in the rolled state has the weakest degree of surface plastic deformation. Scanning electron microscope images of the thermal damage area were finally selected, and the thermal fatigue crack damage on the surface was quantitatively analyzed using computer image processing software and analysis software. It was found that the de-stressed state W had the smallest crack area and the smallest number of cracks for the same thickness, indicating that the de-stressed state W had the strongest resistance to irradiation damage. The experimental results also show that, in addition to the effect of microstructure, both the uniaxial stress state and the crack-blocking mechanism of the laminated structured W-PFM contribute to the improvement of its thermal fatigue performance.

show abstract

Section: N P R E S Sunclassified

Influence of microstructure on thermal fatigue effect of laminated tungsten based plasma-facing material

Qi,

Ma,

et al. 2024

Acta Phys. Sin.

View full text Add to dashboard Cite

show abstract

“…According to current tokamak designs, during normal operation, especially in the divertor region, W-PFMs must withstand harsh fusion environments, including high fluxes of low-energy particles (H/He) and neutron irradiation, as well as extreme heat loads and repeated severe thermal shocks generated by long-pulse discharges [3][4][5]. Under cyclic thermal loading, the surface of W-PFMs will experience thermal damage, such as brittle cracking and fatigue cracks [6,7]. These crack damages may worsen during the service life of W-PFMs, eventually leading to their degradation and failure, and even affecting the stability of the plasma.…”

Section: Introductionmentioning

confidence: 99%

Finite Element Analysis and Experimental Verification of Thermal Fatigue of W-PFM with Stacked Structure

Qi,

Song

et al. 2024

Metals

View full text Add to dashboard Cite

As the prime candidate for plasma-facing materials (PFM), the response of tungsten (W) to thermal shock loads is an important research topic for future fusion devices. Under heat loads, the surface of tungsten plasma-facing materials (W-PFM) can experience thermal damage, including brittle cracking and fatigue cracks. Therefore, exploring solutions for thermal damage of W-PFM remains one of the current research focuses. We propose a novel approach to mitigate thermal radiation damage in PFM, namely, the stacked structure W-PFM. The surface thermal stress distribution of the stacked structure W-PFM under heat loads was simulated and analyzed by the finite element method. As the foil thickness decreases, both the peak thermal stresses in the normal direction (ND) and rolling direction (RD) decrease. When the thickness decreases to a certain value, the peak thermal stress in the RD decreases to about 1384 MPa and no longer decreases; while the peak thermal stress in the ND approaches 0 MPa and can be neglected. In the range of approximately 5–100 mm, the accumulated equivalent plastic strain decreases sharply as the thickness decreases; in other thickness ranges, it decreases slowly. Thermal fatigue experiments were conducted on the stacked structure W composed of W foils with different thicknesses and bulk W using an electron beam facility. The samples were applied with a power density of 30 MW/m2 for 10,000 and 20,000 pulses. The cracks on the surface of the stacked structure W extended along the ND direction, while on the surface of bulk W, besides the main crack in the ND direction, a crack network also formed. The experimental results were consistent with finite element simulations. When the pulse number was 10,000, as the thickness of the W foil decreased, the number and width of the cracks on the surface of the stacked structure W decreased. Only four small cracks were present on the surface of stacked structure W (0.05 mm). When the pulse number increased to 20,000, the plastic deformation and number of cracks on the surface of all samples increased. However, the stacked structure W (0.05 mm) only added one small crack and had the smallest surface roughness (Ra = 1.536 μm). Quantitative analysis of the fatigue cracks showed that the stacked structure W-PFM (0.05 mm) exhibited superior thermal fatigue performance.

show abstract

Microstructure-based crack formation in tungsten exposed to cyclic transient heating

Cited by 2 publications

References 65 publications

Influence of microstructure on thermal fatigue effect of laminated tungsten based plasma-facing material

Influence of microstructure on thermal fatigue effect of laminated tungsten based plasma-facing material

Finite Element Analysis and Experimental Verification of Thermal Fatigue of W-PFM with Stacked Structure

Contact Info

Product

Resources

About