When manufacturing steel components, it is critical to keep an eye on the basics as the industry evolves and new materials become available. Tensile and yield strength are no exception, and it pays to recall the fundamentals:
In this article, we'll review the fundamentals of both tensile and yield strength and talk through how these factor into the material selection process.
A steel's tensile strength is the maximum stress the material can handle before fracturing. Tensile strength is also called ultimate tensile strength, or UTS.
The yield strength of a material refers to the maximum stress it can withstand without undergoing permanent deformation. Once this value (known as the elastic limit) is exceeded, the steel can no longer regain its original shape, even if the load is removed.
As is true for UTS, yield strength in steel is influenced by a number of factors, including chemical composition and processing, among others. For instance, adding certain elements or using specific heat treatments can improve yield strength, allowing engineers to tailor steel properties for particular applications. Designers must know a steel’s yield strength, as well as its UTS, to ensure a component can handle the expected loads safely.
Both tensile and yield strength (typically measured in KSI or MPa) are important to component designers, both for quality assurance and confidence that a component will perform as expected. Tensile and yield strength of steel can be determined via standardized testing methods, such as ASTM E8/E8M, ASTM A370, or ISO 6892-1.
Practically speaking, for non-critical applications, yield strength often dictates when a component will reach the point where it can no longer perform an intended function or meet design specifications) and tensile strength determines when a steel will completely fail.
In other words:
In brittle metals, yield and tensile strengths are typically very similar, meaning the point at which a steel begins to deform is also when it begins to break. A ductile steel, which is more malleable, will reach its yield strength before its tensile strength, deforming before breaking.
Yield and tensile strength in steel are important, but they don’t tell the entire story. Application-specific conditions can help complete the picture.
Problem: Elevated operational temperatures can potentially reduce a steel component’s yield or tensile strength over time.
We recommend: A specialized, heat-resistant aerospace steel grade, such as Jethete M152.
Problem: Applications with harsh or oxidation-inducing environments may require corrosion-resistant steel to ensure performance.
We recommend: XD16N or XD15NW®, a high-performance, corrosion-resistant grade for critical applications.
Problem: During operation, a component may endure cyclical forces, leading to fatigue.
We recommend: Choosing your steel on a case-by-case basis; while a material with high tensile strength often also exhibits high fatigue resistance, this is not always true. If fatigue is an issue for your application, we recommend a consultation to determine your best option.
At Sullivan Steel, we specialize in supplying high-performance grades for demanding industries. Our experts can help with specific advice regarding material selection, heat treatment, melt practice, and more.
If you’re dealing with a demanding application or have questions about one of the grades discussed above, we can help! Start a Live Chat or contact us to get started.