What is AISI 4140 Material? Advantages and Properties

4140 has medium carbon content. it is a popular steel in different industries due to its versatility and unique properties. It has a combination of elements like chromium and molybdenum which enhance its mechanical properties. It is usually available in bars. There are many other important features in 4140 steel which are discussed in this article.

What is 4140 Steel?

4140 PH steel is a low alloy material. A combination of alloying elements like Cr, Mo and Mn increases its mechanical properties like toughness, strength, abrasion and impact resistance and good ductility. Not all the steel grades have this much versatility and uniqueness as the 4140 has.

Is 4140 Steel Magnetic?

Yes, 4140 PH steel is magnetic and has good magnetic properties. It can attract magnet and can stick to it.

Is 4140 a Carbon or Alloy Steel?

4140 is a carbon steel. it has carbon content of 0.38-0.43% which classifies it as a medium carbon alloy. in fact, that is why it has good ductility and other mechanical properties.

Is 4140 High Carbon Steel

No, it is classified as medium carbon steel. because it has carbon content of 0.38-0.43%.

Is 4140 Tool Steel?

Yes, it has characteristics of tool steel. it provides a unique combination of strength, toughness, abrasion and corrosion resistance.

Will 4140 Steel Rust?

No 4140 has good corrosion resistance. it can survive in harsh conditions without being rust.

What Are the Common Forms of 4140 Material?

• 4140 steel rods

These are cold drawn in annealed conditions. These rods have high hardenability, good hardness penetration, and high strength.

• 4140 bar stock

4140 bar stocks are round shaped, bar of oil-hardening having 6-120 mm dimensions. These bars have high strength, wear resistance, toughness and good ductility.

• 4140 tubing

4140 tubing are employed in general-purpose high toughness and tensile strength applications.

• 4140 Sheets

The cold rolled 4140 sheets or plates of 1-10mm thickness have high hardness and toughness.

What is 4140 Alloy Steel Good for?

4140 PH steel has multiple uses due to its uniqueness and versatility. Some of them are as:

• 4140 PH steel is employed in various parts and components in automotive, oil and gas and aerospace industries. These parts are such as gears, suspension systems, axle, crankshafts and bulldozer blades.
• 4140 steel is also famous for its strength to withstand high stresses and wear. It is most suitable for high-stress applications like construction equipment and machineries and engine parts like landing gears and fasteners.
• 4140 ordnance steel is employed in production of consumer goods like sporting goods, hand tools and other goods that needs high wear resistance and tensile strength.

What is 4140 Steel Equivalent To?

4140 ordnance steel is equivalent to following standards:

Advantages and Disadvantages of 4140 Steel?

4140 ordnance steel has limitless advantages. Few of them are written below:

• 4140 PH steel has high torsional strength and fatigue resistance.
• It has remarkable mechanical properties like tensile strength and good ductility.
• The corrosion resistance, wear and abrasion resistance are exceptional. It is a demanding alloy where high wear resistance is required
• The medium carbon content increases its hardness in annealed conditions.
• It can easily be hardened by heat treatment which is a preferred feature in many industrial applications.

There are also some drawbacks associated with 4140 PH steel which are as:

• Weldability of 4140 ordnance steel is low and it is hard to weld. It requires post weld heat treatment to avoid cracks. Its weldability is only recommended in annealed conditions.
• Preheating is required before welding. Slow-cooling and reheating is required which increases the time and cost of production.

4140 Steel Chemical Composition

The chemical composition of 4140 steel is as:

4140 Steel Material Properties

Density

The density of 4140 Ph steel is 7.85g/cm3

Hardness Range

Brinell hardness is 197 of 4140 steel, Knoop hardness id 219 and Vicker hardness is 207.

Hardness Rockwell

The Rockwell B hardness is 92HRB and Rockwell C is 13HRC for 4140 steel.

Strength

4140 steel has high mechanical properties like toughness, yield strength, tensile strength and fatigue strength.

Yield Strength

Yield strength of 4140 steel is 415MPa

Yield Stress

The yield stress of 4140 steel is 140 GPa.

Tensile Strength

AISI 4140 has tensile strength of 95,000 psi. It I used for applications that requires high structural integrity.

Thermal conductivity

thermal conductivity of 4140 steel is 42.6 W/mK @100°C.

Electrical conductivity

The electrical conductivity of 4140 steel is 7.84% IACS.

Thermal Expansion

Thermal expansion of 4140 steel is 12.2 µm/m°C @0-100°C.

Machinability Rating

The machinability rating of 4140 steel is 65%.

Can 4140 be Welded to Mild Steel?

Weldability of 4140 ordnance steel is low. It is difficult to weld due to high hardness. This hardness is due to high carbon content, Cr and Mo in the composition. This makes it prone to cracking during welding. The post weld heat treatments are required to avoid cracking in welds

TIG Welding 4140 Steel

TIG welding can be carried out on 4140 steel but it is not recommended in handed and tempered conditions.

Stick Welding 4140 Steel

Hydrogen electrodes are recommended for 4140 steel followed by post weld heat treatment with slow cooling rate to avoid weld cracking.

Heat Treatment

4140 PH steel is heat treated at temperature 845°C and then quenched in oil. If it is to be hardened, then normalizing carried out at 913°C for a long holding time and then air cooled.

Annealing, Quenching, Tempering, and Their Effects on Properties

To get good results of annealing, tempering and other heat treatments, following practice must be followed.

Annealing

4140 steel can be annealed at 872°C and then furnace cooled at slow cooling rate to get optimized hardness and strength.

Tempering

to increases the hardness at different levels of 4140 alloy, tempering is carried out at 205 to 649°C. Low temperature results in higher hardness.

Quenching

Quenching of 4140 steel is normally carried out to increase the hardness. Cold working also has effective results in hardness.

AISI 4140 Material VS Other

What is Stronger, 4130 or 4140 Steel?

4140 is stronger than 4130 which is suitable for high-stress applications.

7075 billet aluminum vs 4140 steel

4140 steel has higher strength, toughness and wear resistance than 7075 billet aluminum.

1045 vs 4140 Steel

4140 steel has higher strength and hardness while 1045 has better weldability and machinability.

1018 vs 4140 Steel

4140 has higher impact strength and tensile strength than 1018 steel.

S7 Tool Steel vs 4140

S7 tool steel has higher shock resistance while 4140 has higher hardness, strength, toughness and is affordable.

8620 Steel vs 4140

4140 is better in toughness and strength than 8620

4140 Chrome Moly Steel vs 416 Stainless

416 is very expensive than 4140 steel. however, both have excellent mechanical properties.