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Precipitation Hardening Stainless Steel

April 22nd, 2021

Precipitation hardening stainless steels are metals that have martensitic or semi-austenitic properties and contain high percentages of chromium and nickel. These steels are used in various industrial applications because of their high strength, corrosion resistance and hardness. Precipitation hardening stainless steels get their high tensile strength from undergoing a series of heat treatments. This specialized heat treatment process includes the addition of Copper, Aluminum and Titanium to enhance the steel’s corrosion resistance. Here’s everything you need to know about precipitation hardening stainless steels:

Stainless Steel Classifications 

Precipitation hardening stainless steels are put into three groups based on their properties after the heat treatments. These alloy groups are martensitic, semi-austenitic and austenitic.

Austenitic Alloys: Austenitic stainless steels largely retain their structure after the heat treatment process. The alloy should undergo annealing, reheating and hardening treatments. The steel should be heated to no more than 2050 degrees Fahrenheit during the annealing procedure. Precipitation occurs during the reheating process, which increases the hardness and strength of the steel.

Martensitic Alloys: Martensitic stainless steels should be heated to no more than 1950 degrees Fahrenheit during the annealing heating process. During the cooling part of the process, this material undergoes a classification transformation from austenite to martensite.

Semi-Austenitic Alloys: Unlike other types of precipitation hardening steels, semi-austenitic steels are relatively low on the hardness scale and can be cold worked. Austenitic alloys maintain their original structure at room temperature but transform to martensite when exposed to extremely low temperatures.

Precipitation Hardening Stainless Steel Applications 

Because of the hardness and high tensile strength of this classification of stainless steels, many applications are in the high technology or aerospace engineering fields. These steels are used to manufacture the following components:

• Gears
• Valves
• Shafts
• Specialized engine components
• Turbine blades
• Molding dies

While these are the most routine functions, these steels can be used in any tool or component that requires a high degree of strength and hardness. 

Benefits of Precipitation Hardening Stainless Steel

One of the significant benefits of using precipitation hardening steels is that they can be treated to take on many favorable properties. These characteristics include:

Corrosion Resistance: Precipitation hardening steels have greater corrosion resistance than standard stainless steels, which is particularly beneficial when the steel is used in an outdoor or extreme weather application. The corrosion resistance of the steel can generally be enhanced during the heat treatment process.

Formability: Many grades of semi-austenitic stainless steel can be molded without any heat treatments. On the other hand, martensitic stainless steels are tough both before and after the heat treatment process and are therefore not easily formed.  

Weldability: Unlike other stainless steel alloys, precipitation hardening steels can be readily welded through standard fusion and resistance methods. Remember that special care should be taken during the heat treatment process to ensure that the optimum mechanical properties for weldability are achieved.

This is not a comprehensive list of the advantages of using precipitin stainless steels. Other benefits including affordability, malleability and tool longevity. 

Precipitation Hardening Stainless Steels Fabrications 

Special care should be taken during the stainless steel fabrication process to ensure no cross-contamination occurs. All fabrication should be done with tools specially made for stainless steel, and all devices should be sanitized before and after each use. If tools are not thoroughly cleaned, contamination that causes color discoloration of the fabricated mechanism can happen.

Founded in 1956, Specialty Steel Treating is a respected leader in the steel treatment industry. We provide heat treatment services for the aerospace, automotive, heavy equipment, commercial aircraft and heavy equipment industries. We offer several high-quality steel treatment services to our clients, including tempering, case hardening, oil quenching, precipitation hardening, and more.