030070245-Cem Ertürk 11th week bonus part 2

River Patterns ( Mechanical Failure Type)


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Cleavage fracture is a brittle fracture mode. Cleavage fractures are characterind by a plmar crack that changes planes by the formation of discrete steps. River patterns are formed at grain boundaries where the cleavage plane in one grain is not parallel to the plane nine adjacent grain, the difference being accommo-dated by a series of steps. The river patterns eventually diminish as the crack propagates and adopts the cleavage plane of the new grain be-fore being reformed at the next grain boundary. 


( Campbell F.C. Elements of Metallurgy and Engineering Alloys, Page:223)

Radiation Embrittlement ( Mechanical Failure Type)

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Definitions is from a conference. Radiations Enbrittlement know as neutron radiation embrittlemenet. This definitions mentioned about effect on steels but it was inform about effects on the material.

The neutron radiation embrittlement of reactor premure ye.eft in nuclear power plants is of prime interest to the industry in America today. The general effect in steels caues them to become harder, stronger, less ductile, and more brittle. At Geneva Skvortsov  summarized the Russian evaluation of radiation effects in pressure vessels steels succinctly (in its translation) by saying "... this influence (of radiation) causes an increase of brittlenesss creating 'unpleasant' conditions for the mechanical propertits of the vessel material." 


(American Society for Testing Materials, Material in Nuclear Apllications: Presented at the Third Pacific Conference, Page:116)