Log out Go to App
Go to App

Learning Materials

Features

Discover

Chapter 11: Problem 5

On the basis of microstructure, briefly explain why gray iron is brittle and weak in tension.

Short Answer

Expert verified
Answer: Gray iron is brittle and weak in tension primarily due to its microstructure, which consists of graphite flakes and a matrix of either ferrite or pearlite (or both). The graphite flakes act as stress concentrators and provide easy paths for crack initiation and propagation, making the material prone to failure under tensile stress. The presence of ferrite in the matrix contributes to the weakness in tension, as it is a soft and ductile phase unable to resist deformation effectively.

Step by step solution

01

Introduction to Gray Iron

Gray iron, also known as cast iron, is an iron-carbon alloy that has a relatively high carbon content (around 2-4%). The microstructure of gray iron consists of a network of graphite flakes embedded in a matrix (ferrite, pearlite, or a combination of both).
02

Graphite Flakes in Gray Iron

One of the main characteristics of gray iron is the presence of graphite flakes, which form during the solidification of the iron-carbon alloy. The graphite flakes cause stress concentrations and act as crack initiators, making the material inherently more brittle.
03

Weakness in Tension

The elongated graphite flakes create stress concentration points, which provide easy paths for crack initiation and propagation. As a result, gray iron is more susceptible to failure under tensile stress due to the fragile nature of these stress points causing the material to fracture.
04

Matrix Microstructure

The matrix in gray iron is usually composed of ferrite, pearlite, or a combination of both. Ferrite is a soft, ductile phase, while pearlite is a harder, stronger phase. The presence of ferrite makes gray iron weak in tension, as it is unable to resist deformation effectively. On the other hand, the presence of pearlite can increase the strength of the material; however, the brittleness remains due to the presence of graphite flakes.
05

Summary

In summary, gray iron is brittle and weak in tension primarily due to its microstructure, which consists of graphite flakes and a matrix of either ferrite or pearlite (or both). The graphite flakes act as stress concentrators and provide easy paths for crack initiation and propagation, making the material prone to failure under tensile stress. The presence of ferrite in the matrix contributes to the weakness in tension, as it is a soft and ductile phase unable to resist deformation effectively.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Start your free trial

Over 30 million students worldwide already upgrade their learning with Vaia!

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

Name two thermal properties of a liquid medium that will influence its quenching effectiveness.

Compute the volume percent of graphite \(V_{\mathrm{Gr}}\) in a \(3.5 \mathrm{wt} \% \mathrm{C}\) cast iron, assuming that all the carbon exists as the graphite phase. Assume densities of \(7.9\) and \(2.3 \mathrm{~g} / \mathrm{cm}^{3}\) for ferrite and graphite, respectively.

Compare sand, die, investment, lost foam. and continuous casting techniques.

List four situations in which casting is the preferred fabrication technique.

Give the distinctive features, limitations, and applications of the following alloy groups: titanium alloys, refractory metals, superalloys, and noble metals.
See all solutions

Recommended explanations on Physics Textbooks

Physics of Motion

Read Explanation

Magnetism and Electromagnetic Induction

Read Explanation

Energy Physics

Read Explanation

Scientific Method Physics

Read Explanation

Electricity and Magnetism

Read Explanation

Solid State Physics

Read Explanation
View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.

Sign-up for free