Chapter 13, Problem 13.18P

Interpretation Introduction

(a)

Interpretation:

The term "Quenching" needs to be explained.

Concept Introduction:

Quenching is one of the important concepts in material science and metallurgy. In quenching the fast cooling of workpiece takes place in order to obtain required material characteristics. In the cooling process, the cooling fluids used are water, air, oil. Quenching is the advantageous in case of low-temperature process like phase transformation.

Interpretation Introduction

(b)

Interpretation:

The term "Tempering" needs to be explained.

Concept Introduction:

To change the undesirable properties of steel as well as cast iron into desirable and commercially acceptable, various methods are used in which tampering is one of them, it is a heat treating, progress the toughness especially of iron-based alloys.

Tempering method is done by heating the metal to particular temperature, but the temperature must be below the critical point for a certain period of time.

Interpretation Introduction

(c)

Interpretation:

The term "retained austenite" needs to be explained.

Concept Introduction:

To change the undesirable properties of steel as well as cast iron into desirable and commercially acceptable, various methods are used in which retained austenite is one of them, In the retained austenite process, austenite that does not completely transform to martensite quenching.

This retained austenite microconstituent occurs when the steel is not quenched to a temperature low enough to form 100% martensite.

Interpretation Introduction

(d)

Interpretation:

The term "mar-quenching or "martempering" needs to be explained.

Concept Introduction:

Martempering is also called as interrupted quenching or stepped quenching. The steel above the transformation range or critical point is heated in this process.

In this method, the austenite is a transformed to martensite at stepped quenching, at a rate fast sufficient to avoid the formation of ferrite, bainite or pearlite.