MATERIAL SCIENCE PRESENTATION

Presenting My

MATERIAL SCIENCE PRESENTATION

Plastic Modes Of Deformations

INDEX

Deformation Meaning

Plastics Deformation

Introduction

Video

Still Images

Properties

Slip Mode

Modes

Difference

Thanks

11

12

10

Twinning Mode

Difference

INTRODUCTION

When enough load is applied to a material or a structure, it will cause the material to change shape. This change in shape is known as deformation.

PLASTIC DEFORMATION

As per the material science theory, when sufficient stress is applied to cause permanent deformation to the metal, it is called plastic deformation. In Simple ,The process due to which an object changes its size or shape due to applied force, that is irreversible, is known as plastic deformation. It can be observed in many objects like: Concrete Plastics Soils Metals Rocks Example: steel rod bending.

Properties Of Plastic Deformation

Even after the removal of the applied forces when the deformation stays, it is irreversible

The property of the material to undergo enduring the deformation under pressure is known as plasticity. It is the state or quality of plastic material, especially the molding and altering capacity.

The malleability and ductility of a material are directly proportional to plasticity of the material. For an ideal plasticity property of material, it is to undergo irreversible deformation without any increase in load or stress.

Fracture or rupture of the material may be caused by plasticity. Plasticity also leads to plastic deformation, which happens in many metal forming processes like forging, pressing, rolling, swaging, etc.

Difference between Elastic Deformation & Plastic Deformation

When energy goes into changing the shape of some material and it stays changed, that is said to be plastic deformation. When the material goes back to its original form, that's elastic deformation. Elastic deformation is a temporary deformation under the action of external loading. Plastic deformation is the permanent deformation.

MODES OF PLASTIC DEFORMATION

The plastic deformation may occur by one (or both ) of the following modes :

1) Slip

2) Twinning

#1 SLIP

The term 'slip' may be defined as a shear deformation ,which moved the atomes through many inter aratomic distances,relative to their initial positions. The deformation by slip is as shown as in fig. here

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The Slip deformation is analogous to a deck of cards when it is pushed from one end.

In simple we can say, It occurs in crystallographic planes or slip planes and involves the sliding of blocks of crystal over one another.

During slip each atom usually moves same integral number of atomic distances along the slip plane producing a step, but the orientation of the crystal remains the same.

MECHANISM

THe direction in which the slip moves is known as slip direction & the plane on which slip occurs is known as slip plane. The combination of slip plane & slip direction is known as Slip System.

#2 TWINNING

The term 'TWINNING' may be defined as a plastic deformation ,which takes place along two planes due to set of forces applied on a given metal piece.. The deformation by twinning is as shown as in fig. here

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ILLUSTRATION

Properties

Twinning only occurs when slip can’t take place .

The twinning portion is mirror image of parent portion .

The plane of symentry is called twinning plane

VS

TWINNING MODE

SLIP MODE

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COMPARISON BETWEEN SLIP & TWINNING

First, for slip, the crystallographic orientation above and below the slip plane is the same both before and after the deformation; for twinning, there is a reorientation across the twin plane.

COMPARISON BETWEEN SLIP & TWINNING

First, for slip, the crystallographic orientation above and below the slip plane is the same both before and after the deformation; for twinning, there is a reorientation across the twin plane.

In addition, slip occurs in distinct atomic spacing multiples, whereas the atomic displacement for twinning is less than the interatomic separation.

COMPARISON BETWEEN SLIP & TWINNING

First, for slip, the crystallographic orientation above and below the slip plane is the same both before and after the deformation; for twinning, there is a reorientation across the twin plane.

In addition, slip occurs in distinct atomic spacing multiples, whereas the atomic displacement for twinning is less than the interatomic separation.

Slip occurs on relatively widely spread planes, but in the twinned region of a crystal every atomic plane is involved in the deformation.

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