Chapter 12, Problem 12.92P

Interpretation Introduction

Interpretation:

The hardness of 1080 steel, austenite at ${\text{775}}^{\text{o}}\text{C}$ for one hour and quenched to

  ${\text{550}}^{\text{o}}\text{C}$ needs to be explained. The time required to hold the austenite at ${\text{550}}^{\text{o}}\text{C}$ for thecomplete transformation needs to be calculated.

Concept introduction:

Material hardness is a property of the material due to which material resist the plastic deformation. Plastic deformation is a non-reversible change in the material after applying an external force. Hardness is the property of material which possess stiffness, resistance to bending, scratching or cutting. Hardness is not constant for fixed for all the material, but it depends upon strength and plasticity of metal. Material hardness is expressed in terms of Hardness number.