Microstructure-Properties: I Fracture Toughness - Materials Science ...
Microstructure-Properties: I Fracture Toughness - Materials Science ...
Microstructure-Properties: I Fracture Toughness - Materials Science ...
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32<br />
Objective<br />
Overview<br />
Crack<br />
Minimztn.<br />
Energy<br />
Absrptin.<br />
2A Transformation toughening:<br />
quantitative approach<br />
• It is not possible to lay out the details of how to<br />
describe transformation toughening in a fully<br />
quantitative fashion here.<br />
• An equation that describes the toughening effect is as<br />
follows, where K is the increment in toughness (units of<br />
stress intensity, MPa√m):<br />
∆K = C E V trans ε trans √h / (1-ν)<br />
C is a constant (of order 1), E = elastic modulus,<br />
V trans = volume fraction transformed,<br />
ε trans = transformation strain (dilatation, i.e. bulk<br />
expansion), h is the width of the process zone, and ν is<br />
Poisson’s ratio.<br />
• What controls the width of the process zone?
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