Fractographic correlations with mechanical properties in ferritic martensitic steels

Abstract

The ultimate continuum of a material is nothing but the process called fracture. Fracture surface retains the imprint of the entire deformation history undergone in a material. Hence, it is possible to derive the approximate deformation and fracture properties of a material from a systematic fracture feature analysis. There has been large volume of literature available in the open domain correlating different mechanical and fracture responses of reduced activation ferritic martensitic grade steels under various testing conditions/circumstances with corresponding microstructural interpretation. There has been no such literature available to establish the relationship between the two-dimensional fracture geometry/topography with its corresponding deformation and mechanical properties of the material as a function of testing temperature, which has been the primary aim in the current investigation. A comprehensive literature survey has been carried out to realize this fact. In order to establish the above hypothesis, many tensile experiments were carried out at constant strain rate by systematic variation of the test temperature. The initial void volume fraction or the inclusion content of material was kept unaltered and the test temperature has been varied orderly on different multiple specimens to vary the deformation-induced nucleation sites of micro voids (i.e. different carbides, phase interfaces, dislocation pile up etc), which results in a change of fracture topography under uniaxial tensile deformation. A conventional metallographic technique followed by optical microscopy has been employed to understand the basic morphologies and characteristics of the alloy exposed at different temperatures. Fractographic investigation of the broken tensile specimens at various temperatures is carried out to measure the fracture features by using quantitative fractography on representative scanning electron fractographs through image processing.

Influence of surface roughness, friction coefficient, and wrap angle on clinching joint strength and its correlation with belt friction phenomenon

“…This kind of layer with continuous shear marks (also termed as transfer layer) is typically observed in the higher FC range. 44,53,54 Further, the rolling marks found to be intact on the surface can be seen for lower FC. However, there are no such marks for higher FC, which indicates a higher wrap angle for higher FC.…”

Microstructural Changes Caused by the Creep Test in ZK60 Alloy Reinforced by SiCp at Intermediate Temperature after KOBO Extrusion and Aging

“…Elongated dimples are related to the direction of the applied stress. Cavitation during creep is the cause of the extensive dispersion of fine dimples and indicates the level of intergranular fracture [ 57 ]. Very fine dimples are related to the presence of reinforcements in the matrix.…”

Void Nucleation and Growth from Heterophases and the Exploitation of New Toughening Mechanisms in Metals

“…Then, Goods and Brown reviewed the theories of void nucleation [6], including the void nucleation mechanisms derived from plastic deformation at grain boundaries, inclusions, and second-phase particles. Das and Chakravartty [7] have provided a comprehensive literature review of the different void nucleating sites for various alloys, indicating that micro voids intermittently form from a variety of elastic discontinuities such as inclusions, second phases, grain boundaries, etc. In an early review by Curran et al [8], experimentally observed nucleation sites of voids were listed along with their associated nucleation mechanisms and loading parameters.…”