A general method for estimation of fracture surface roughness: Part I. Theoretical aspects

Gokhale, A.M.; Underwood, Ervin E.

doi:10.1007/bf02656538

Cited by 23 publications

(10 citation statements)

References 8 publications

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“…Despite inconsistencies in the results, some general consensus is now emerging among researchers [4,[7][8][9][10][11][12][13][14][15][16][17]. Similar classes of materials are thought to exhibit similar behavior.…”

Section: Introductionmentioning

confidence: 99%

Relationship between Fracture Toughness and Fracture Surface Fractal Dimension in AISI 4340 Steel

Carney¹,

Mecholsky²

2013

MSA

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This study analyzes the relationship between fracture toughness and the fracture surface fractal dimension for a set of twenty-four CT-type AISI 4340 steel specimens heat treated to a variety of tensile strengths. Specimens were tested in accordance with ASTM E 399. Their respective fracture surfaces were plated, polished, photographed under an SEM in BSE mode and measured according to the Richardson method to obtain fractal dimensions. For brittle materials the limited results are consistent with previous literature: increasing fractal dimension with increasing toughness. For partially or fully ductile materials the results indicate a decrease in fractal dimension with an increase in fracture toughness. The data are modeled using a variation of the function applied to ceramics. Fracture in a ductile mode is characterized by the formation of dimples which exhibit fractal characteristics. The results are discussed in terms of the micromechanisms of fracture.

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Section: Introductionmentioning

confidence: 99%

Relationship between Fracture Toughness and Fracture Surface Fractal Dimension in AISI 4340 Steel

Carney¹,

Mecholsky²

2013

MSA

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“…The calculated curves and fitting curves for DL of fracture surface were shown in Figure 7. It can be seen from Figure 7 that the fitting curve between lgs(t) and lg(t) of gray value distribution contour curve of fracture surface at the different horizontal position of the SEM is accordance with linear model: (6) Where a and b are constants related to the gray value distribution, the larger the a is, the larger the D L is, the more complex the contour curve is, and the more fine structure is. From Eq.…”

Section: Resultsmentioning

confidence: 70%

“…But , the reports on the micro-morphology characteristics of fracture surface found that an uneven fracture surface with low smoothness would formed during subjecting to external load due to the different material structure and molding parameters, and the surface topography of the fracture had multi-levels [4][5][6]. The much finer structure in the fracture surface will appear constantly with the increasing of magnification times of the scanning electron microscope.…”

Section: Introductionmentioning

confidence: 99%

A Study on the Gray Value Distribution Contour Curve Extraction Based on the Image of the Fracture Surface of the Material and Its Fractal Dimension

Tian¹,

Liu²,

Cheng-bao³

et al. 2017

Proceedings of the 2017 5th International Conference on Machinery, Materials and Computing Technology (ICMMCT 2017)

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Abstract. It was proposed that the gray value distribution contour curve of the fracture surface of material was used to represent the true contour curve of fracture surface, the gray value distribution contour curve was extracted by the image analysis software IPP(Image Pro-Plus), and the fractal dimension of the gray value distribution contour curve of the fracture surface was measured by the structure function method as polypropylene (PP) was the sample, in order to characterize the morphological characteristic of the fracture surface of material. The results indicated that the gray value distribution contour curve could reflect the multilevel of the fracture surface of the material; the fractal dimension of gray value distribution contour curve of PP was 1.6375, the linear degree of fitted by the structure function method was high and the correlation coefficients obtained were more than 0.99. The strong 1inear correlation indicated that impact fracture surface of the PP had significant fractal characteristics. Thus using the fractal dimensions to describe the fracture surface morphology of material may provide a new approach to investigate the morphology of fracture surface of materials.

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“…where λ 0 is the actual measured length of fracture profile and L is equivalent straight path (projected length). RL can vary between 1 and ∞ depending on the irregularity of the fracture profile [28,29]. This parameter can be used to quantify the crack deflection and could be an accurate criterion for comparing the fatigue crack paths in different microstructures.…”

Section: Crack Path Analysis and Fractographymentioning

confidence: 99%

Role of Microstructure Heterogeneity on Fatigue Crack Propagation of Low-Alloyed PM Steels in the As-Sintered Condition

Mousavinasab

Blais

2017

Metals

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Due to their lower production costs, powder metallurgy (PM) steels are increasingly being considered for replacing wrought counterparts. Nevertheless, the presence of a non-negligible volume fraction of porosity in typical PM steels makes their use difficult, especially in applications where cyclic loading is involved. On the other hand, PM offers the possibility of obtaining steel microstructures that cannot be found in wrought. Indeed, by adequately using alloying strategies based on admixing, pre-alloying, diffusion bonding or combinations of those, it is possible to tailor the final microstructure to obtain a distribution of phases that could possibly increase the fatigue resistance of PM steel components. Therefore, a detailed study of the effect of different microstructural phases on fatigue crack propagation in PM steels was performed using admixed nickel PM steels (FN0208) as well as pre-alloyed PM steels (FL5208). Specimens were pressed and sintered to a density of 7.3 g/cm 3 in order to specifically investigate the effect of matrix microstructure on fatigue properties. Fatigue crack growth rates were measured at four different R-ratios, 0.1, 0.3, 0.5 and 0.7 for both PM steels. The negative effect of increasing the R-ratio on fatigue properties was observed for both alloys. The crack propagation path was characterized using quantitative image analysis of fracture surfaces. Measurements of roughness profile and volume fractions of each phase along the crack path were made to determine the preferred crack path. Weak Ni-rich ferritic rings in the FN0208 series (heterogeneous microstructure) caused a larger crack deflection compared to the more homogeneous microstructure of the FL5208 series. It was determined that, contrary to results reported in literature, crack propagation does not pass through retained austenite areas even though fatigue cracks propagated predominantly along prior particle boundaries, i.e., intergranular fracture.

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A general method for estimation of fracture surface roughness: Part I. Theoretical aspects

Cited by 23 publications

References 8 publications

Relationship between Fracture Toughness and Fracture Surface Fractal Dimension in AISI 4340 Steel

Relationship between Fracture Toughness and Fracture Surface Fractal Dimension in AISI 4340 Steel

A Study on the Gray Value Distribution Contour Curve Extraction Based on the Image of the Fracture Surface of the Material and Its Fractal Dimension

Role of Microstructure Heterogeneity on Fatigue Crack Propagation of Low-Alloyed PM Steels in the As-Sintered Condition

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