• June 13th 2023

8620 steel is a popular low-alloy steel that is commonly used in various industrial applications due to its excellent mechanical properties, including high strength, toughness, and good hardenability. This essay aims to provide a comprehensive understanding of 8620 steel and its equivalent materials, focusing on their properties, applications, and the factors to consider when selecting an alternative material. The essay is organized into the following sections:

  1. Overview of 8620 Steel
  2. Equivalent Materials
  3. Factors to Consider When Selecting an Equivalent Material
  4. Summary

1. Overview of 8620 Steel

8620 steel, also known as SAE 8620 or AISI 8620, is a low-alloy steel composed of nickel, chromium, and molybdenum. It belongs to the SAE-AISI family of materials, which are specified by the Society of Automotive Engineers (SAE) and the American Iron and Steel Institute (AISI). The primary composition of 8620 steel includes approximately 0.18-0.23% carbon, 0.40-0.70% manganese, 0.035% phosphorus, 0.040% sulfur, 0.15-0.25% silicon, 0.40-0.60% chromium, 0.40-0.70% nickel, and 0.15-0.25% molybdenum.

The combination of these elements provides 8620 steel with a unique set of mechanical properties, such as high strength, excellent toughness, and good hardenability. These properties make it a popular choice for various applications, including gears, camshafts, crankshafts, and fasteners, among others.

2. Equivalent Materials

There are several materials that can be considered as equivalents to 8620 steel due to their similar chemical compositions and mechanical properties. Some of the most common equivalent materials are:

2.1. AISI 4140 Steel

AISI 4140 steel is a chromium-molybdenum alloy steel with a composition of approximately 0.38-0.43% carbon, 0.75-1.00% manganese, 0.035% phosphorus, 0.040% sulfur, 0.15-0.35% silicon, 0.80-1.10% chromium, and 0.15-0.25% molybdenum. It exhibits high strength, good toughness, and excellent resistance to wear and fatigue. Due to its superior mechanical properties, AISI 4140 steel is often used as a substitute for 8620 steel in applications that require higher strength and wear resistance.

2.2. SAE 9310 Steel

SAE 9310 steel is a nickel-chromium-molybdenum case-hardening steel with a composition that includes approximately 0.08-0.13% carbon, 0.45-0.65% manganese, 0.025% phosphorus, 0.025% sulfur, 0.20% silicon, 1.00-1.40% chromium, 3.00-3.50% nickel, and 0.08-0.15% molybdenum. This steel offers high strength, excellent toughness, and good hardenability, making it a suitable alternative to 8620 steel in applications where enhanced wear resistance and fatigue properties are required.

2.3. 20MnCr5 Steel

20MnCr5 steel, also known as 1.7147 or 20MnCrS5, is a case-hardening steel with a composition of approximately 0.17-0.22% carbon, 1.10-1.40% manganese, 0.035% phosphorus, 0.035% sulfur, 0.15-0.40% silicon, and 1.00-1.30% chromium. This steel is characterized by its good hardenability, high strength, and good wear resistance, making it an appropriate alternative to 8620 steel for certain applications.

2.4. 18CrNiMo7-6 Steel

18CrNiMo7-6 steel, also known as 1.6587 or 17CrNiMo6, is a case-hardening steel with a composition that includes approximately 0.17% carbon, 0.50% manganese, 0.035% phosphorus, 0.035% sulfur, 0.40% silicon, 1.50-1.80% chromium, 1.40-1.70% nickel,and 0.25-0.35% molybdenum. It is known for its excellent hardenability, high fatigue strength, and good wear resistance, making it a suitable substitute for 8620 steel in applications requiring superior performance in these areas.

3. Factors to Consider When Selecting an Equivalent Material

When choosing an equivalent material for 8620 steel, several factors should be considered to ensure that the selected material meets the specific requirements of the application. These factors include:

Mechanical Properties: It is crucial to select a material with similar or superior mechanical properties to 8620 steel, such as strength, toughness, and hardenability. This ensures that the material can withstand the stresses and strains associated with the intended application.

Wear Resistance: Depending on the application, wear resistance may be an essential factor to consider. Materials with higher wear resistance can extend the service life of components and reduce maintenance costs.

Fatigue Resistance: In applications where components are subjected to cyclic loading or stress, fatigue resistance becomes a critical factor. Materials with higher fatigue resistance can better withstand repeated stress cycles without failure.

Machinability and Formability: The ease with which a material can be machined and formed into the desired shape is another important factor. Materials with good machinability and formability reduce manufacturing costs and improve production efficiency.

Cost: The cost of the material is always an important consideration when selecting an alternative material. While some materials may offer improved properties, they may also come at a higher cost, making them a less viable option for certain applications.

Availability: The availability of the material should also be considered. Some materials may be more readily available than others, which can affect lead times and overall project timelines.

By carefully considering these factors, an appropriate equivalent material for 8620 steel can be selected that meets the specific requirements of the application.

4. Summary

8620 steel is a low-alloy steel with excellent mechanical properties, including high strength, toughness, and good hardenability. Its unique combination of elements makes it a popular choice for various industrial applications, such as gears, camshafts, crankshafts, and fasteners.

Several materials can be considered as equivalents to 8620 steel due to their similar chemical compositions and mechanical properties. These include AISI 4140 steel, SAE 9310 steel, 20MnCr5 steel, and 18CrNiMo7-6 steel. Each of these materials offers its own set of advantages and can be suitable alternatives to 8620 steel in certain applications.

When selecting an equivalent material, it is vital to consider factors such as mechanical properties, wear resistance, fatigue resistance, machinability, formability, cost, and availability. By carefully evaluating these factors, an appropriate material can be chosen that meets the specific requirements of the application and provides similar or superior performance compared to 8620 steel.