Table of Contents
What is 5160 Steel
5160 Steel is one of the most important manufacturing materials used in modern industry. It is a metal made from alloying iron with carbon and other trace elements, where these additions provide the steel with increased strength, resistance, and hardness.
Steel can be made in many different ways, and so different types of steels have been classified based on their compositions (to gain a better understanding of the differences between steels, read our article on the types of steels). The American Iron & Steel Institute (AISI) and the Society of Automotive Engineers (SAE) have developed a joint naming system for different alloys, which describes the chemical composition and generalized characteristics of each steel. This article will explore the properties, strengths, and uses of 5160 steel, a low alloy high strength spring steel which is exceptionally resilient and tough. By exploring its physical, chemical, and mechanical properties, this article hopes to show readers when to choose 5160 steel over other, less well-suited alloys for their project.
Physical Properties of 5160 Steel
It is important to understand the naming system for steel and its alloys, as the name reveals much about the composition of each alloy. Much like aluminum, steel is named using a four-digit identifier, but unlike aluminum, each number holds important information regarding the percentage of carbon and the associated alloying elements within the steel alloy. Also note that there are discontinuities between the AISI and SAE naming systems, but they are generally overlapping in terms of alloy names and will be treated as one naming entity in this article (AISI/SAE naming index).
The first digit of the steel alloy nomenclature represents the class of the steel alloy. In the case of 5160 aluminum, the 5 represents steel alloys that utilize chromium as the major alloying element. The second digit represents the concentration of the aforementioned alloying element; 5160 steel is therefore 1% chromium by mass. The last two digits represent the specific concentration of carbon, where they designate that the alloy is 0.XX % carbon. For 5160 steel, that means that the carbon concentration is 0.60% carbon, making it a medium to high carbon steel. Note that this is not a comprehensive analysis, and to be considered 5160 steel, the material must also achieve the concentration tolerances for the other elements as shown below:
0.75-1% Manganese
0.035% Phosphorus
≤ 0.15-0.3% Silicon
≤ 0.04% Sulfur
5160 steel is exceptionally tough and resilient. It sports a high level of resistance to fatigue, has high ductility, and has good spring qualities useful for applications where flexibility is desired. It is, therefore, part of the “spring steels”, which represent those alloys that are both flexible but have enough strength to return to their original shape post-deformation. While not easily welded or machined, 5160 steel can be heat-treated, annealed, and hot worked into shape. It has a density of 7.85 g/cm3 (0.284 lb/in3).
Corrosion weakness
5160 steel is easily rusted, which is an unfortunate side effect that most steels will exhibit. The oxygen in the air and in water attacks the iron molecules in the steel and forms iron oxide, also known as rust, which can introduce cracks and weak points in the steel. Chromium is added to help prevent this rusting, but there is not enough by mass to fully prevent degradation. Any caustic damage will weaken 5160 steel, so it is important to consider the rust risk of your project when implementing this metal.
Mechanical Properties
Table 1: Summary of mechanical properties for 6063 aluminum alloy.
| Mechanical Properties | Metric Value | English Value |
| Ultimate Tensile Strength | 958 MPa | 139000 psi |
| Tensile Yield Strength | 530 MPa | 76900 psi |
| Bulk Modulus | 160 GPa | 23200 ksi |
| Modulus of Elasticity | 205 GPa | 29700 ksi |
| Shear Modulus | 80.0 GPa | 11600 ksi |
shown above, provides some basic mechanical values of 5160 steel. This section will briefly explore each value and its relevance to the working characteristics of this highly useful material.
The ultimate tensile and tensile yield strength are values that describe a material’s response to being in tension. The yield strength describes the maximum tensile force that will not permanently deform a specimen of steel, and the ultimate strength is the maximum tensile force before failure (fracturing/cracking). 5160 steel is exceedingly strong in tension, and sports values much higher than even the strongest aluminum (for comparison, 7075 aluminum, a considerably strong aluminum alloy, has an ultimate yield strength of 572 MPa / 503 MPa, respectively). These strengths show why this steel is a formidable spring steel, as it can take a beating before ever deforming permanently.
The bulk modulus describes how resistant a material is to uniform compression – in other words, how difficult it is to decrease the volume of an object while in axial loading. 5160 steel’s bulk modulus is 160 GPa, which means that it is almost 80 times harder to compress than liquid water (the bulk modulus of water is 2.15 GPa). This again shows why 5160 steel is perfect as a spring steel; automobile suspensions are often in constant compression and must not waver under constant compressive force.
Similarly, both the shear and elastic moduli show the resilience of a material in response to both shear and elastic stresses, respectively. They provide a good indication of the overall toughness of a material, as well as what stresses the material is susceptible to. 5160 steel does not have to worry about many weaknesses, as both its shear and elastic moduli are impressively large. It is interesting to note that the machinability and workability of a material are often inversely related to these two measures, as a stronger and more resilient steel will gum up mills and generally give machinists more grief.
Applications of 5160 Steel
5160 steel is, as previously described, an ideal spring steel. Its hefty strength is often implemented in applications with smaller cross-sections under significant stress such as springs, fasteners, and leaf springs in automobile suspensions. It comes in bar and tube forms from suppliers and can be used to create exceptionally strong components, granted that you have the tools to process it. 5160 steel is also utilized when building scrapers and bumpers, and can make a great knife edge that is both durable and flexible. If ductility, toughness, and resilience are needed, consider asking your supplier about 5160 steel.
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