Archive for the ‘Fracture mechanics’ Category
Monday, March 20th, 2006
Most groups of alloys can exhibit failure by cracking in circumstances where the apparent applied stress is well below that at which failure would normally be expected. Steels are no exception to this, and probably exhibit a wider variety of failure mechanisms than any other category of ...
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Monday, March 20th, 2006
Temper embrittlement is inherent in many steels and can be characterized by reduced impact toughness. The state of temper embrittlement has practically no effect on other mechanical properties at room temperature.
Figure 1 shows schematically the effect of temperature on impact toughness of alloy steel which is strongly ...
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Monday, March 20th, 2006
Current and developing applications for materials at low temperatures include structures, vehicles, and pipeline equipment for arctic environments, storage and transport equipment for liquefied fuel gasses, oxygen and nitrogen, and superconducting machinery, devices and electrical transmission systems. Most of these applications relate to the ...
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Monday, March 20th, 2006
The effect of carbon additions between 0.3 and 0.8%
In hypoeuteetoid steels containing between 0.3 and 0.8% carbon, proeutectoid ferrite is the continuous phase and forms primarily at austenite grain boundaries. The pearlite forms inside the austenite grains and makes up between 35-100% of the microstructure. More than ...
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Monday, March 20th, 2006
There are literally thousands of steels available today, each one characterized by a particular trade name or alloy composition. Although a quantitative value of fracture toughness parameters (e.g., NDT temperature and KIC) for each grade would greatly facilitate the selection of a material for a particular application, ...
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Monday, March 20th, 2006
Fracture is an inhomogeneous process of deformation that makes regions of material to separate and load-carrying capacity to decrease to zero. It can be viewed on many levels, depending on the size of the fractured region that is of interest. At the atomistic level fracture occurs over ...
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Monday, March 20th, 2006
Plastic Zone Size
Materials develop plastic strains as the yield stress is exceeded in the region near the crack tip (see Fig. 1). The amount of plastic deformation is restricted by the surrounding material, which remains elastic. The size of this plastic zone is dependent on the stress ...
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Monday, March 20th, 2006
The fatigue life of a component is made up of initiation and propagation stages. This is illustrated schematically in Fig. 1
Figure 1. Initiation and propagation portions of fatigue lifeThe size of the crack at the transition from initiation to propagation is usually unknown and often depends on ...
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Monday, March 20th, 2006
Ductile fracture
A pure and inclusion free metal can elongate under tension to give approx. 100% RA and a point fracture, Fig. 1. Most alloys contain second phases which lose cohesion with the matrix or fracture and the voids so formed grow as dislocations flow into them. Coalescence ...
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