Fracture metal

Mechanical sources friction, impact, vihration, metal fracture... 

A metal fracture characterized by considerable plastic deformation, the tearing of metal and an appreciable expenditure of energy, as occurs with repeated bending of a strip of metal. 

Cooper G.A. and Kelly A. (1967). Tensile properties of fiber-reinforced metals Fracture mechanics. J. Mech. Phys. Solids 15. 279-297. 

TRANSITION TEMPERATURE. 1. An arbitrarily defined temperature within die temperature range in which metal fracture characteristics determined usually by notched tests are changing rapidly such as from primarily fibrous (shear) to primarily crystalline (cleavage) fracture. 

Fig. 12.81. Accumulated hydrogen (originating in electrochemical formation at the surface) produces cracks inside a metal. When it is strained, the metal fractures along the cracks rather than yielding. It has become brittle.

Erosion Similar to abrasion cutting in ductile metal fracture (of brittle material) very small chips or particles (e.g., impellers, propellers, fans) Reduce fluid velocity to eliminate turbulence select harder alloy (high chromium) hard coatings such as cement lined pipe, rubber lining... 

Brittle fracture is exhibited when metals fracture with a relatively small or negligible amount of plastic strain. 

CORROSION, FATIGUE - The process in which a metal fractures prematurely under conditions of simultaneous corrosion and repeated cyclic loading at lower stress levels or fewer cycles than would be required in the absence of the corrosive environment. 

British thermal unit (Btu) A British thermal unit is the energy needed to raise the temperature of 1 lb of water ]°F (0.6°C) at sea level. As an example, one lb of solid waste usually contains 4,500 to 5,000 Btu. Plastic waste contains greater Btu than other materials of waste. See calorie energy consumption heat, brittle Easily broken, damaged, disrupted, cracked, snapped. See design-failure theory, Griffith metal fracture. 

Post-test metallographic examination of longitudinal sections of composite weld tensile samples provided data on the location of the fracture and the presence of secondary intergranular cracking. Base metal fracture locations were experienced with K-58 GTA welds at room temperature (RT), K-58 GTA/CW/PR (see Table II for notation) and K-58 GTA/CW/FR welds at all temperatures, Pyromet 538 GTA welds at all temperatures, Pyromet 538 SMA welds at RT, and A-286 GTA welds at RT. Weld FZ fractures were experienced with all 310S SMA welds, K-58 GTA welds below room temperature, K-58... 

Transverse weld joint strength in all weldments exceeded 665 MPa at room temperature. Tensile tests of the two types of steel showed different behaviors. For the nickel steels, 25°C specimens fractured in the base metal, and all cryogenic specimens fractured in the weld metal. This performance is typical for nickel steel weldments prepared with undermatching low-temperature strength Inconel filler metals. In the stainless weldment, the test performance was reversed, with weld metal fractures at 25°C and base metal fractures at -160 and -196°C. 

To shear the material, the flat-rolled metal is placed between the shear s upper and lower knives which are slightly offset in the vertical plane. Typically, the lower knife is stationary and the upper knife is movable. Commonly, the upper knife can be adjusted for the correct horizontal clearance (the horizontal distance between the upper and lower blades when they pass) and rake (the angle formed between the upper and lower knives). As the upper knife proceeds downward under the shear force, it penetrates the metal, but before it completely passes through the metal, the metal fractures and separates into two pieces. 

Ramsdellite [Named after the American mineralogist, Lewis Stephen Ramsdell (1895-1975) who first described the mineral] (ICSD 78331 and PDF 44-142) MnO, M = 86.93685 63.19 wt.% Mn 36.81 wt.%0 (Oxides, and hydroxides) Orthorhombic Biaxial 3 4370 Habib massive, fibrous, platy. Color steel gray or black. Diaphaneity opaque. Luster metallic. Fracture brittle. Streak brownish black. Occurrence manganese deposits with pyrohidte... 

Balankin, A. S., Ivanova, V. S., Breusov, V. P. (1992). A Collective Effects in Metals Fracture Kinetics and Dissipative Structure Fractal Dimension Spontaneous Change at Ductile-Brittle Transition. Doklady AN, 322(6), 1080-1086. 

Corrosion fatigue is a process in which a metal fractures by fatigue prematurely under conditions of simultaneous corrosion and repeated cycUc loading at lower stress levels than would be otherwise required in the absence of a corrosive environment. Metals and alloys will crack in the absence of corrosion if they are subject to high cycUc stress for a number of cycles. The number of cycles for failure decreases as the stress is increased. Below a certain stress the metal will last indefinitely. This level is termed as "Endurance Limit of the material. 

Prior to the advent of fracture mechanics as a scientific discipline, impact testing techniques were estabhshed to ascertain the fracture characteristics of materials at high loading rates. It was realized that the results of laboratory tensile tests (at low loading rates) could not be extrapolated to predict fracture behavior. For example, under some circumstances, normally ductile metals fracture abruptly and with very little plastic deformation imder high loading rates. Impact test conditions were chosen to represent those most severe relative to the potential for fracture —namely, (1) deformation at a relatively low temperature, (2) a high strain rate (i.e., rate of deformation), and (3) a triaxial stress state (which may be introduced by the presence of a notch). 

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