Forged steel: Meaning, properties, grades, composition

Forged steel has been in existence for centuries. Simply put, forged steel is raw steel going under extreme temperatures to be later molded into different shapes like bars, screws, nuts, etc. This steel is made in large factories with the help of specialised machines or hydraulic hammers.

What is forged steel?

Steel products or materials like rivets and bolts made in a forge following the forging process is called forged steel. This steel is vital for certain industries including the automotive and aerospace industry to make landing gear, turbines, levers, etc.

Most metals can be forged including alloy steel. The most common types of metals that are forged include aluminum, brass, copper, carbon, alloy, stainless steel, titanium, nickel, cobalt and molybdenum.

To understand forged steel, you must understand the process of forging.

The process of forging

Forging is a metalworking process. It means shaping, deforming, and compressing metals to achieve a desired form, configuration, or appearance as per a metal processing design or diagram. For accurate steel forging multiple methods are used which are automated functions in modern factories.

Let us understand the steel forging process with an example. Have you ever wondered how a spanner is made? Spanner is a forged steel product that is used for many engineering applications.

Have a look at how a spanner is made:

1. Manufacturer obtains steel bars as the raw material to make spanners
2. The steel bars are cut into sections
3. The sections are sandblasted to remove all impurities
4. The sections undergo hot rolling and hammer moulding
5. These are fed into an induction furnace and are heated up to 1250°C. The sections become malleable and ductile so they can be compressed into the desired shape
6. These are passed through a hot rolling mill to get an elongated shape roughly matching the length of the spanner
7. These pieces are put underneath the hammer machine which compresses the pieces between two moulds, shaped like the spanner
8. The spanners are then left to cool
9. The extra material around the spanner is then cut off by a machine
10. The spanners are then polished and embossed with the manufacturer’s trademark

Some of the forged steel materials produced are tempered. Tempering process makes steel stronger. Tempering involves heating, shaping, cooling, and reheating, which creates stress. By tempering this steel product, it becomes less brittle and more ductile without compensating for the hardness. The process produces harder and tougher parts that are weldable and ductile.

Also read: Stainless steel: Definition, features, uses, types and more

Features and properties

Here are some of the features and properties of forged steel components:

• When steel is heated and compressed, minor cracks are sealed up and empty spaces found in the material are closed. This creates a strong component.
• Forging alters the grain structure of steel. Therefore, forging steel can give it a favorable grain structure, making the steel sturdier.
• Steel forge parts feature better reliability and tolerance capabilities
• Forging lends steel components uniformity of composition and structure.
• They can handle high loads and stresses
• They are free from gas voids, pockets, or cooling defects which often decreases the capacity of steel to bear stress

Examples of forged steel products used in various industries

Forged steel parts are used when the manufacturer requires steel products of absolute quality. The strength, reliability, and durability of forged parts make them suitable for heavy duty stressful applications.

Here are some forged steel products used in various industries:

• Hand tooling industry – Hammers, spanners, pliers and garden tools
• Automotive industry – Wheel spindles, steering arms, ball joints, axle beams, and kingpins
• Oil industry – Casings and coverings of valve bodies, reducers, saddles, and flanges
• Mining industry- Drill bits, crusher hammers and conveyors
• Railway industry – Gears, levers, joints, transmissions, rollers and hubs
• Aerospace industry – Landing gears, turbines and shafts for jet engines

Forged steel grades

The grade of the raw material steel product used to make the forged steel component is its grade. For example, if a mild steel  billet of the grade Fe 415 is used to make a bolt, the grade of the forged steel bolt is Fe 415.

These are the common grades of steel used to make these components are:

• Fe 415, Fe 415D, Fe 415S
• Fe 500, Fe 500D, Fe 500S
• Fe 550, Fe 550D
• Fe 600

Forged steel composition

As per the IS Code, every type of steel used to forge into a component has different chemical composition. For example, carbon steel used for forging will have a different chemical composition standard as per IS regulations compared to tool steel.

Given below is the chemical composition standard for steel used in carbon steel forgings for general engineering purposes. For this standard IS Code has assigned nine classes of carbon steel forgings; Class 1, 1A, 2, 2A, 3, 3A, 4, 5 and 6.

Steel class	Component and percentage allowed
	Carbon	Silicon	Manganese	Sulphur (Max)	Phosphorus (Max)
1	0.10-0.18	0.15-0.35	0.40-0.70	0.04	0.04
1A	0.10-0.20	0.15-0.35	0.60-0.90	0.04	0.04
2	0.15-0.25	0.15-0.35	0.60-0.90	0.04	0.04
2A	0.20-0.30	0.15-0.35	0.60-0.90	0.04	0.04
3	0.25-0.35	0.15-0.35	0.60-0.90	0.04	0.04
3A	0.30-0.40	0.15-0.35	0.60-0.90	0.04	0.04
4	0.40-0.50	0.15-0.35	0.60-0.90	0.04	0.04
5	0.50-0.60	0.15-0.35	0.60-0.90	0.04	0.04
6	0.60-0.70	0.15-0.35	0.50-0.80	0.04	0.04

There are also specifications for tensile strength, yield strength, elongation, etc., for steel used in carbon steel forgings assigned by the IS Code 2004:1991.

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