13-8 and 17-4 Stainless Steel – What’s the Difference

13-8 Stainless Steel vs 17-4 Stainless Steel

Choosing the right material for a particular application is critical, especially in aerospace, medical, and nuclear industries, where safety and reliability are paramount. Among the different materials available, stainless steel is a popular choice due to its admirable strength, durability, and corrosion resistance. However, not all stainless steels are created equal, and it’s essential to understand the distinguishing characteristics of each type to determine the best one for your project. In this blog post, we’ll explore two specific variations of stainless steel – 13-8 and 17-4 – and highlight their key differences.

Difference Between 13-8 and 17-4 Stainless Steel

Chemical Composition:

The primary difference between 13-8 and 17-4 stainless steel is their chemical compositions. 13-8 is a chromium-nickel-molybdenum stainless steel that contains approximately 13% chromium, 8% nickel, and 2% molybdenum. On the other hand, 17-4 is a chromium-nickel-copper stainless steel comprising 17% chromium, 4% nickel, 3% copper, and minor quantities of carbon, manganese, and silicon.

Hardness and Strength:

Another significant difference between these stainless steels is their hardness and strength properties. 17-4 stainless steel is a precipitation-hardening, martensitic stainless steel. It acquires its impressive strength through ageing, which involves heating the metal to high temperatures and cooling it rapidly to achieve a very hard microstructure. In contrast, 13-8 is a precipitation-hardening, semi-austenitic stainless steel that acquires high strength by adding molybdenum and nitrogen. It’s softer and less brittle than 17-4, making it more suitable for high-impact applications.

Corrosion Resistance:

The corrosion resistance of stainless steel is one of its most crucial properties. In the case of 13-8 and 17-4, both exhibit excellent resistance to corrosion. 13-8 is particularly well-suited for resisting stress corrosion cracking, a common phenomenon in high-strength applications. 17-4, on the other hand, is more resistant to pitting and crevice corrosion, making it a preferred choice for marine environments.


Machinability refers to the ease with which a metal can be cut, shaped, or drilled. In this regard, 13-8 is known to have better machinability than 17-4 stainless steel, primarily due to its less brittle nature. However, both materials require special handling and tooling to ensure a high-quality finished product.


The cost of a material is often a crucial factor in determining its suitability for a particular application. Here, 13-8 is usually more expensive than 17-4 stainless steel. This difference in cost is primarily due to the higher levels of nickel, molybdenum, and nitrogen present in 13-8, making it a more premium alloy.


In conclusion, the choice between 13-8 and 17-4 stainless steel ultimately comes down to the specific needs of the project at hand. Understanding each material’s chemical composition, hardness, strength, corrosion resistance, machinability, and cost is crucial in making an informed decision. Whether you require a higher-strength material for impact resistance or a corrosion-resistant one for marine environments, knowing the differences between these stainless steel sheets will help you choose the right one for the job.



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