Deformation & Strengthening Mechanisms

What is the slip process?

Plastic deformation which occurs by motion of dislocations

Caterpillar locomotion

hump formed and propelled by lifting and shifting of leg pairs

Dislocation motion

movement of extra half plane of atoms by breaking and reforming of interatomic bonds

Slip system is a combination of what 2 things

Slip plane and slip direction

slip plane definition

crystallographic plane on which slip occurs most easily, plane with high planar density

slip direction

crystallographic direction along which slip occurs most easily, direction with high linear density

What is the slip system for FCC crystal structure?

dislocation motion planes: {111}

dislocation motion directions: <110>

What is applied tensile stress

shear stress component when slip plane oriented neither perpendicular nor parallel to stress direction

Critical resolved shear stress

the minimum shear stress required to initiate slip in a crystal under an applied stress.

Polycrystalline materials have ____ grains?

many grains with often random crystallographic orientations

What are the 3 strengthening mechanisms

grain size reduction, solid solution strengthening, strain hardening (cold working)

Metals with small grains

relatively strong and tough at low temperatures

Metals having large grains

good creep resistance at relatively high temperatures