Steels and its grades? (R)

Steel is very important to our modern life and the infrastructure of every country fully depends on steel. I believe that everyone knows the main sources of steel are natural and the structure with the combination of chemical elements based on applications. It consists of Iron (Fe) and carbon (C). Carbon and iron with the other elements, played a major role in determining the characteristics and strength of steels.

By arranging the set combination of iron and carbon with key elements, there are 3000 plus different materials used for the applications. You can determine the grade of the material by validating the quantity of carbon and other alloying elements and other properties based on the applications. To maintain the grades universally, the set combination and other alloying elements are standardized for each grade and can be validated wherever required.

In this article, we will discuss the classification of steels. The method of grade determination and heat treatment activities.

The Four types of Steel

1. Carbon Steels

2. Alloy Steels

3. Stainless Steels

4. Tool Steels

Carbon steels

Carbon steel frequently used material in industries across the world. Most of the applications are satisfied with carbon steel. In the set combination of iron and carbon, there are other elements are added to manufacture the carbon steels. There are five essential elements that are base and common for all kinds of steels and these elements are Carbon, Silicon, Manganese, Phosphor, and Sulphur.

With the level of carbon, these steels are classified further as.

1.   Carbon up to 0.3% is called as low carbon steel

2.   Carbon from 0.3% to 0.6% is called medium carbon steel

3.   Carbon from 0.6% is called as called as High carbon steel

 

These carbon steels are standardized as ASTM A6 / IS 2062 / EN 10025

 

Alloy steels

Alloy steels are made, by combining the key elements with essential elements. These key elements are Chromium, Molybdenum, Nickel, Vanadium, Boron, Copper, and aluminum. These key elements play a key role in providing strength, ductility, hardness, corrosion resistance, and machinability.

These alloy steels are standardized as ASTM A287

Stainless steels

Stainless steels also called austenite steels and grades are alloyed with 10 to 20% chromium, nickel with essential elements. These grades are specially standardized for high corrosion resistance. The purpose is to survive adverse weather and is mostly used in harsh environments.

Stainless steels are graded as SS 304 / SS 316 / Duplex grades and precipitated hardened stainless steels. Mainly used for electrical device industries, food industries, Oil and Gas industries, and Power industries. Etc.,

Tool steels

Tool steels excel in cutting and drilling equipment. The important elements are tungsten, molybdenum, cobalt, and vanadium help to improve heat resistance and general durability.

Apart from the four groups based on composition, steel can also be classified based on different variables including:

·         Finishing method: hot rolled, cold rolled, cold finished, etc.

·         Production method: electric furnace, continuous cast, etc.

·         Microstructure: ferritic, pearlitic, martensitic, etc.

·         Physical strength: per ASTM standards

·         De-oxidation process: killed or semi-killed

·         Heat treatment: annealed, tempered, etc.

·         Quality nomenclature: commercial quality, pressure vessel quality, drawing quality, etc.