What are Wallner lines?
A distinct pattern of intersecting sets of parallel lines, usually producing a set of V-shaped lines, sometimes observed when viewing brittle fracture surfaces at high magnification in an electron microscope.
What is fractography used for?
Fractography is a method in failure analysis for studying the fracture surface of materials. Studying the characteristics of the fractured surface can help to determine the cause of failure in an engineered product.
What are rib marks?
Rib marks represent pauses in the advance of the main fracture; as the advance slows, the fracture deflects through 900 until it is at right angles to the main fracture surface; on re-starting it curves back to its original direction (fig. 1, b).
What is fracture analysis in geology?
Fracture analysis can help us define structural axes and trends or fracture-related reservoir properties. To determine reservoir-property requires integrating geology, petrophysics, and reservoir engineering, and it is most often done by experienced specialists.
How is fractography done?
In many cases, fractography requires examination at a finer scale, which is usually carried out in a scanning electron microscope or SEM. The resolution is much higher than the optical microscope, although samples are examined in a partial vacuum and colour is absent.
What is the meaning of fractography?
Fractography is the study of fracture surfaces in order to determine the relation between the microstructure and the mechanism(s) of crack initiation and propagation and, eventually, the root cause of the fracture.
What are Conchoidal lines?
Conchoidal (shell-like) fracture patterns in the glass are the result of stress on the glass and breakage due to application of a force. The two types of conchoidal fractures are radial and concentric. Radial fractures extend outward in a line from the point on the glass where the force originated.
What are radial cracks?
Radial cracks are fractures extending outward from the point of impact. Ream is an imperfection; nonhomogeneous layers of flat glass. Wallner lines (ridges) are rib-shaped marks with a wave-like pattern.
What is cleavage and fracture?
Cleavage is the property of a mineral that allows it to break smoothly along specific internal planes (called cleavage planes) when the mineral is struck sharply with a hammer. Fracture is the property of a mineral breaking in a more or less random pattern with no smooth planar surfaces.
What causes intergranular fracture?
Intergranular fractures travel along the grain boundaries, rather than through the actual grains. This usually occurs when the phase in the grain boundary is weak and brittle (such as cementite in iron’s grain boundaries).