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4140 vs 4145 Steel – What’s the Difference

4140 vs 4145 Steel

When choosing the correct steel for your project, not all types of steel are created equal. Two commonly used steel types for industrial and commercial applications are 4140 and 4145. While both of these steel grades have similarities in composition and mechanical properties, they also have significant differences that make them unique. This blog post will explore the difference between 4140 vs 4145 steel, their properties, and their advantages.

Differences between 4140 and 4145 Steel


4140 is a low-alloy steel containing chromium, molybdenum, and manganese. This composition gives the steel high strength, toughness, and wear resistance. The added chromium element enhances the steel’s corrosion resistance, while molybdenum improves its hardenability. On the other hand, 4145 steel is chromium-molybdenum combination steel with an added 0.20% to 0.25% vanadium. The vanadium content enhances the steel’s strength, toughness and hardenability, making it suitable for high-stress applications, including drilling and heavy-duty machinery.

Mechanical and Physical Properties

While both 4140 and 4145 steel have high strength and toughness, 4145 steel has a higher tensile strength and yield strength than 4140 steel. This strength difference means that 4145 steel can withstand high-stress levels, making it ideal in harsh environments and heavy-duty applications. While 4140 steel is easier to weld and machine, 4145 steel is more challenging to weld and machine due to its high hardenability. 4140 steel has good strength and toughness but is not ideal for high-stress applications.


4140 Steel is commonly used in oil and gas for drilling collars, pump shafts, gears, and shafts. Other applications of 4140 steel include automotive parts, machinery, heavy-duty cranes and construction equipment. Alternatively, 4145 steel is ideal for the oil and gas industry, specifically for drilling tools, mud motors, and jars. It is also used in high-stress applications, including aerospace, military, and defence.

Cost and Availability

The cost of 4140 steel is typically lower than that of 4145 steel due to its lower percentage of vanadium. However, the cost of both steels depends on their availability and market demand. The price may also be higher in regions with higher demand for either steel type. Both 4140 and 4145 steel are readily available from suppliers across the United States.


In conclusion, 4140 and 4145 steel have similar composition and mechanical properties. However, several critical differences make them unique and ideal for various applications. While 4140 steel is suitable for low-stress applications due to its ease of welding and machining, 4145 steel is ideal for high-stress applications thanks to its high hardenability, strength, and toughness. Ultimately, the choice of steel type will depend on the application’s specific needs and the budget. Contact your steel supplier for advice on which steel type suits your project’s needs.

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