Low Alloy Steels

LOW ALLOY STEELS

1. What are Low Alloy Steels?

✓ Low alloy steels are steels which contain upto 3 to 4% of one or more alloying elements.

✓ They have similar microstructure and require similar heat treatments to that of the plain carbon steels. ondas of 

✓ They are also referred as pearlitic alloy steels as the normalised structure contains the eutectoid pearlite.

✓ The presence of alloying elements provide enhanced properties such as increased strength without loss of toughness and increased hardenability.

✓ The applications of low-alloy steels are similar to those quoted in Table 3.2 for plain carbon steels of equivalent carbon content.

2. Types of Low Alloy Steels

The low alloy steels are subdivided into two broad groups:

1. AISI steels, and

2. HSLA steels.

1. AISI Steels

✓ AISI (American Iron and Steel Institute) steels are steels that are generally used in machine construction.

✓ AISI steels are sometimes also referred as construction steels or structural steels.

✓ AISI steels normally have less than about 5% total addition of elements such as Cr, Ni, Cu, Mn, Mo, V, etc.

✓ The property of major interest in this AISI steels group is hardenability.

2. HSLA Steels

✓ HSLA (High-Strength Low-Alloy) steels, also known as micro- alloyed steels, have been developed by making micro-alloying additions of the elements Al, Nb↑ and V, either singly or in combination, to give a major grain refinement.

✓ The HSLA steels will be discussed in Section 3.14.