Difference Between Low Alloy Steel and High Alloy Steel

The key difference between low alloy steel and high alloy steel is that low alloy steels have less than 0.2% alloying element, whereas high alloy steels have more than 5% alloying element.

An alloy is a mixture of two or more elements. It is produced from mixing metal with some other elements (metals or nonmetals or both) to obtain a material that has enhanced properties compared to the original metal. Low alloy and high alloy steel are two types of alloys of iron.

CONTENTS

1. Overview and Key Difference
2. What is Low Alloy Steel 
3. What is High Alloy Steel
4. Side by Side Comparison – Low Alloy Steel vs High Alloy Steel in Tabular Form
5. Summary

What is Low Alloy Steel?

Low alloy steel is a type of alloy steel whose properties are enhanced compared to carbon steel. For example, this alloy has better mechanical properties and greater corrosion resistance than carbon steel. The carbon content of low alloy steel is less than 0.2%. Alloying elements other than carbon include Ni, Cr, Mo, V, B, W and Cu.

Most of the times, the manufacturing process of these alloy steel includes heat treatment and tempering (for normalizing). But now, it tends to include quenching and tempering. Also, almost all low alloy steel materials are weldable. However, the material sometimes requires pre- or post-weld treatments (to avoid cracking).

Some advantages of low alloy steel include the followings:

1. Yield strength
2. Creep strength
3. Oxidation resistance
4. Hydrogen resistance
5. Low-temperature ductility, etc.

Furthermore, this material is very useful in industries, but at temperatures lower than 580°C. If the temperature is higher than that, this material is no longer appropriate because of the lack of sufficient oxidation resistance to cope with high temperatures.

What is High Alloy Steel?

High alloy steel is a type of alloy steel which has more than 5% of alloying steel. Unlike in low alloy steel, the alloying elements for high alloy steel are chromium and nickel. One well-known example of this type of material is stainless steel.

Chromium provides the steel with a thin oxide layer on the steel surface. We call it the latent layer because this layer delays the corrosion of the metal. Moreover, manufacturers usually add a high amount of carbon and manganese in order to give an austenitic nature to the steel. Moreover, this material is costly than low alloy steel.

What is the Difference Between Low Alloy Steel and High Alloy Steel?

Both low and high alloy steel have enhanced properties than carbon steel. However, the key difference between low alloy steel and high alloy steel is that low alloy steels have less than 0.2% alloying element, whereas high alloy steels have more than 5% alloying element. When considering the chemical composition, low alloy steel contains iron, carbon (less than 0.2%), and other alloying elements such as Ni, Cr, Mo, V, B, W and Cu, while high alloy steel contains iron chromium, nickel, carbon, manganese, etc.

The below infographic provides more information reegarding the difference between low alloy steel and high alloy steel .

Summary – Low Alloy Steel vs High Alloy Steel

Both low and high alloy steel have enhanced properties than carbon steel. The key difference between low alloy steel and high alloy steel is that low alloy steels have less than 0.2% alloying element whereas high alloy steels have more than 5% alloying element.

Reference:

1. “High Alloy Steel.” High Alloy Steel – an Overview | ScienceDirect Topics, Available here.

Image Courtesy:

1. “789478” (CC0) via Pxhere
2. “4049725” (CC0) via Pixabay