DUCTILE FRACTURE OF METALS Referring to the stress/strain curve (figure 1). A neck is formed in the tensile specimen, after a specific amount of plastic deformation. The force required for further deformation decreases and it eventually breaks. The specimen fractures by ductile fracture, after extensive plastic deformation. The neck of soft or ductile metals forms the cup-cone fracture shape shown in Figure 2. The study of ductile fracture can be commonly known in terms of subsequent microvoid nucleation and growth. action, and is simply illustrated in Figure 3. The confined microscopic cavities are created at the earliest stage of fracture. These nucleate at the admittance level, second phase particles and probably at grain boundary junctions. The microvoids merge and form an oblong crack that advances outward to the neck threshold. Finally, an outer ring of covering material is all that is left to connect the sample fraction, and it fails by trim. Closer examinations show that the rounded divots on the flat bottom of the hole were in tension and the stretched divots were egg-shaped on the 45° aligned shaving lips (Figure 3). In high-aeration, uninvolved face-centered cubic (FCC) and body-centered cubic (BCC) structured metals, necking to nearly 100% surface contraction is achievable. Figure 1. Plot of stress versus strain of a metal. Figure 2. Photos of fractures. Ductile fracture (A) and brittle fracture (B).Figure 3. Images of the ductile fraction.Figure 4. Ductile fracture of metal.FRAGILE FRACTURE OF METALS AND CERAMICSThe most formidable of all is the brittle fracture. This occurs under fixed packaging, without notice of the impending accident. The metal rod that breaks due to fracturing...... middle of paper ...... materials are ductile and hard are brittle or fragile. Ceramic materials are also known as very hard materials that will not deform plastically under tensile stress, but it will break suddenly after elastic deformation. Therefore, glass and ceramic materials are brittle and breakable. Ceramic materials consisting of small and tiny cracks are the result of their processing. The length of these cracks cannot be assured and the stress concentration, the factor k_σ, is poorly or roughly known, hence the average stress, σₐ, which advances to the fracture in a ceramic, cannot be resolved with precision and security. Ceramics are unstable in traction and must be modeled and designed to be subjected only to compressive stresses. This will be easily or directly noticeable by comparing the difference between the shapes of a steel bridge and a stone bridge..