Compare the Difference Between Similar Terms

Difference Between

Home / Science & Nature / Science / Chemistry / Industrial Chemistry / Difference Between Tempering and Austempering

Difference Between Tempering and Austempering

October 1, 2019 Posted by Madhu

The key difference between tempering and austempering is that tempering is useful in removing the excessive hardness of steel, whereas austempering is important in reducing the distortion of iron alloys.

Tempering and austempering are closely related processes which involve heat treatment of metal alloys, specifically iron alloys such as steel. However, the steps of each process and the final outcome are different from each other.

CONTENTS

1. Overview and Key Difference
2. What is Tempering 
3. What is Austempering
4. Side by Side Comparison – Tempering vs Austempering in Tabular Form
5. Summary

What is Tempering?

Tempering is a process that involves heat treating to increase the toughness of iron-based alloys. Also, this process is very important in removing some of the excessive hardness of steel. In this process, first we need to heat the metal to a temperature below the critical point for some time, and then we need to allow the object to cool in still air. The temperature determines the amount of hardness we can remove from the steel. However, this temperature to which we are going to heat the metal depends on the composition of metal or alloy and its properties. For example, low temperatures are favorable for very hard tools, but soft tools such as springs require high temperatures.

Difference Between Tempering and Austempering

Figure 01: Tempering Colors of Steel

Usually, in industries, we perform the tempering step after the quenching. Therefore, the workpiece of the tempering process is the quenched object, and we need to heat the object with control to a certain temperature that is below the lower critical point of the object. During this heating, the grain structures of the object (ferrite and cementite) tend to convert into an austenite grain structure. This is a single-phase solid solution.

What is Austempering?

Austempering is a process in which the metal alloy develops a metallurgical microstructure. The application of this process is mainly on ferrous alloys having medium to high carbon content. Here, steel and ductile iron are most notable among the alloys. In steel, this process forms a microstructure called “bainite” while in ductile iron it produces “ausferrite” microstructure.

Key Difference - Tempering vs Austempering

Figure 02: Time-Temperature Transformation Diagram Showing the Cooling Curve for Austempering in Red Color

Primarily, we use this process to reduce distortion of the alloy, thereby improving the mechanical properties of the material, i.e. we can increase strength, toughness, etc. In this process, we need to heat the material to the hardening temperature, then cooling it rapidly to the martensite temperature. Then, we need to hold the temperature at this level for a sufficient time to get the bainite structure.

What is the Difference Between Tempering and Austempering?

Tempering and austempering are important in enhancing the mechanical properties of a metal alloy, specifically the iron alloys. The key difference between tempering and austempering is that tempering is useful in removing the excessive hardness of steel, whereas austempering is important in reducing the distortion of iron alloys.

When considering the theory of these two processes, during the heat treatment of the tempering process, the temperature determines the amount of hardness we can remove from the steel. However, in the austempering, formation of either “bainite” structure or “ausferrite” structure strengthen the alloy.

Difference Between Tempering and Austempering in Tabular Form

Summary – Tempering vs Austempering

Tempering and austempering are important in enhancing the mechanical properties of a metal alloy, specifically the iron alloys. The key difference between tempering and austempering is that tempering is useful in removing the excessive hardness of steel, whereas austempering is important in reducing the distortion of iron alloys.

Reference:

1. “Austempering – Hardening and Tempering” Bodycote, Available here.

Image Courtesy:

1. “Tempering standards used in blacksmithing” By Zaereth – Own work (CC0) via Commons Wikimedia
2. “Austempering” By Zapatilla – Own work (Public Domain) via Commons Wikimedia

Related posts:

Difference Between Stalactites and StalagmitesDifference Between Stalactites and Stalagmites Difference Between Heating Oil and DieselDifference Between Heating Oil and Diesel Difference Between Hastelloy C22 and C276Difference Between Hastelloy C22 and C276 Difference Between Soda Lime Glass and Borosilicate GlassDifference Between Soda Lime Glass and Borosilicate Glass Difference Between Cast and Wrought Aluminium AlloysDifference Between Cast and Wrought Aluminium Alloys

Filed Under: Industrial Chemistry

About the Author: Madhu

Madhu is a graduate in Biological Sciences with BSc (Honours) Degree and currently persuing a Masters Degree in Industrial and Environmental Chemistry. With a mind rooted firmly to basic principals of chemistry and passion for ever evolving field of industrial chemistry, she is keenly interested to be a true companion for those who seek knowledge in the subject of chemistry.

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Request Article

Featured Posts

Difference Between Coronavirus and Cold Symptoms

Difference Between Coronavirus and Cold Symptoms

Difference Between Coronavirus and SARS

Difference Between Coronavirus and SARS

Difference Between Coronavirus and Influenza

Difference Between Coronavirus and Influenza

Difference Between Coronavirus and Covid 19

Difference Between Coronavirus and Covid 19

You May Like

Difference Between Sentence and Utterance

Difference Between Sentence and Utterance

Difference Between Allotrope and Isomer

Difference Between Allotrope and Isomer

What is the Difference Between Fatty Alcohol Fatty Acid and Fatty Ester

What is the Difference Between Fatty Alcohol Fatty Acid and Fatty Ester

Difference Between Skating and Skiing

Difference Between Positivism and Empiricism

Difference Between Positivism and Empiricism

Latest Posts

  • What is the Difference Between Pneumatocele and Lung Abscess
  • What is the Difference Between Cytotoxicity and Antiproliferative Activity
  • What is the Difference Between Mylanta and Omeprazole
  • What is the Difference Between Malar Rash and Rosacea
  • What is the Difference Between IVIG and SCIG
  • What is the Difference Between Peripheral Blood Smear and Bone Marrow Smear
  • Home
  • Vacancies
  • About
  • Request Article
  • Contact Us

Copyright © 2010-2018 Difference Between. All rights reserved. Terms of Use and Privacy Policy: Legal.