The role of intergranular fracture on hydrogen-assisted fatigue crack propagation in pure iron at a low stress intensity range

In the present study, the fatigue crack propagation tests of Zr-based metallic glass were conducted in laboratory air, and the fracture surface was observed to clarify the effects of loading frequency and the stress ratio. In spite of being brittle material, the metallic glass showed stable fatigue crack propagation behaviour, and the relationship between the crack propagation rate, da/dN, and the stress intensity range, K, can be divided into three regions as well as conventional crystalline metals. The crack propagation rate can be expressed as a function of the stress intensity range by Paris law in the middle region. The power in Paris law was 1.4, and it is considerably smaller than the value for conventional crystalline metals. The threshold stress intensity range, Kth, was 1.8 MPam1/2. The effects of the stress ratio and the loading frequency were not observed on the relationships, da/dN-K and da/dN-Keff. Then, the fatigue crack propagation of the metallic glass is cycle dependent in laboratory air.

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Effect of TiB Orientation on Near-Threshold Fatigue Crack Propagation in TiB-Reinforced Ti-3Al-2.5V Matrix Composites Treated with Heat Extrusion

Materials ◽

10.3390/ma12223685 ◽

2019 ◽

Vol 12 (22) ◽

pp. 3685 ◽

Cited By ~ 2

Author(s):

Shoichi Kikuchi ◽

Shunsuke Tamai ◽

Takao Kawai ◽

Yoshikazu Nakai ◽

Hiroki Kurita ◽

...

Keyword(s):

Fatigue Crack ◽

Stress Intensity ◽

Crack Propagation ◽

Crack Growth ◽

Fatigue Crack Propagation ◽

Threshold Stress ◽

Matrix Composites ◽

Threshold Stress Intensity ◽

Stress Intensity Range ◽

Intensity Range

TiB-reinforced Ti-3Al-2.5V matrix composites, in which TiB whiskers are oriented parallel to the direction of heat extrusion, were fabricated via mechanical alloying and hot isostatic pressing (HIP). To investigate the near-threshold fatigue crack propagation in TiB-reinforced Ti-3Al-2.5V matrix composites, stress intensity factor K-decreasing tests were conducted for disk-shaped compact specimens having two different orientations of TiB whiskers at force ratios from 0.1 to 0.8 under ambient conditions. The crack growth rates, da/dN, for the composites incorporating TiB whiskers oriented perpendicular to the direction of crack growth were constantly lower than those obtained in the case where the orientation was parallel at the same stress intensity range ΔK, while the threshold stress intensity range, ΔKth, was higher. This effect can be explained by the increase in the degree of roughness-induced crack closure resulting from the perpendicular TiB, because fatigue cracks preferentially propagated across the boundaries between the matrix and the TiB in certain regions. In contrast, the effective threshold stress intensity range, ΔKeff,th, for composites was unaffected by the TiB orientation at low force ratios.

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A CALCULATION OF THE THRESHOLD STRESS INTENSITY RANGE FOR FATIGUE CRACK PROPAGATION IN METALS

Fatigue & Fracture of Engineering Materials & Structures ◽

10.1111/j.1460-2695.1980.tb01113.x ◽

1980 ◽

Vol 3 (2) ◽

pp. 189-192 ◽

Cited By ~ 21

Author(s):

YU CHONGHUA ◽

YAN MINGGAO

Keyword(s):

Fatigue Crack ◽

Stress Intensity ◽

Crack Propagation ◽

Fatigue Crack Propagation ◽

Threshold Stress ◽

Threshold Stress Intensity ◽

Stress Intensity Range ◽

Intensity Range

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Fatigue and Corrosion-Fatigue Crack Propagation in Intermediate-Strength Aluminum Alloys

Journal of Engineering Materials and Technology ◽

10.1115/1.3443142 ◽

1973 ◽

Vol 95 (3) ◽

pp. 150-156 ◽

Cited By ~ 4

Author(s):

T. W. Crooker

Keyword(s):

Growth Rate ◽

Fatigue Crack ◽

Stress Intensity ◽

Aluminum Alloys ◽

Crack Propagation ◽

Fatigue Crack Propagation ◽

High Stress ◽

Stress Intensity Factor Range ◽

Stress Intensity Range ◽

Corrosion Fatigue Crack

Fatigue crack propagation studies were conducted on a variety of intermediate-strength aluminum alloys under high stress-intensity range cycling (ΔK > 10 ksiin.). Tests were conducted in ambient room air and in 3.5-percent NaCl saltwater environments. Data are presented on log-log coordinates in terms of fatigue crack growth rate (da/dN) as a function of the stress-intensity factor range (ΔK). Comparisons are made among similar crack propagation data for steel and titanium alloys.

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