15-5PH and 15-5 Stainless Steel – What’s the Difference?

Stainless steel is a commonly used in various industries like aerospace, petrochemical, and medical. Out of the numerous types of stainless steel available in the marketplace, the 15-5PH and the 15-5 are the two types that are frequently used. Over the years, the popularity of these stainless steel types has increased; however, many professionals still don’t fully understand the differences between them, making it challenging to select the right type of steel for a particular application. Here, we’ll provide a comprehensive guide to comparing 15-5PH and 15-5 stainless steel and why selecting the right one is important for your application.

Difference Between 15-5PH and 15-5 Stainless Steel


The primary difference between 15-5PH and 15-5 stainless steel is their chemical composition. The 15-5PH is precipitation-hardening stainless steel containing 15% chromium, 5% nickel, and 3% copper. Adding copper increases its hardness and strength, providing high resistance to corrosion and stress corrosion cracking. On the other hand, 15-5 stainless steel is martensitic stainless steel, containing 15% chromium and 5% nickel. One similarity between the two types is that both can be heat-treated, but the 15-5PH requires more complicated heat treatment and processes to achieve the desired properties.

Mechanical Properties

The mechanical properties of a material determine its suitability for use in various applications. Adding copper to 15-5PH steel improves its mechanical properties, producing higher hardness, strength, and toughness than 15-5 steel. The hardness of 15-5PH steel ranges from 30-50 HRC (Rockwell hardness scale), while 15-5 steel ranges from 20-43 HRC. The strength of 15-5PH steel is 1000-1100MPa, while 15-5 SS has a strength of 745-930 MPa. Understanding the mechanical properties of each type of steel is essential for selecting a suitable one for the application at hand.


15-5 and 15-5PH stainless steels have different applications depending on their properties. 15-5PH steel is commonly used in the aerospace and defence industry for applications requiring high strength and corrosion resistance, such as missile parts, aircraft fittings, and structural components. On the other hand, 15-5 stainless steel is commonly used in the oil and gas industry for parts that require good corrosion resistance, such as valves, pumps, and flanges, because of its strength and durability. Familiarity with applying each type of steel will help you determine which is best suited for your needs.


The cost of each type of stainless steel is another important factor to consider when selecting the right type for a given application. 15-5 stainless steel is less expensive than 15-5PH, mainly because it is easier to manufacture. In contrast, 15-5PH is more expensive because of the complexity of its manufacturing process (for example, the inclusion of copper requires a complicated cooling process for the steel to become hardened). For more information visit MarketsMartb2b


As we have seen, although 15-5 and 15-5PH stainless steels may look the same, they have significant differences in chemical composition, mechanical properties, applications, and cost. Understanding these differences is crucial for selecting the right type of stainless steel for your application. Therefore, evaluate your application’s requirements before deciding which type of steel to use in your application. And now that you have comprehensive knowledge of the differences between the two, selecting the right steel will be easier than ever before.

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