Ferrium® S53®

Ferrium S53 is a new corrosion resistant, ultra-high strength (280 ksi or 1931 MPa A-basis minimum UTS) VIM/VAR steel for structural aerospace and other applications where 300M (BS S155) and 4340 are typically used, but S53 provides: much greater resistance to general corrosion and to stress corrosion cracking (SCC); excellent resistance to fatigue and to corrosion fatigue; and high hardenability. Its resistance to general corrosion is similar to that of 440C stainless steel, but it has much greater fracture toughness. S53 design allowables are included in MMPDS-05, and S53 is covered by SAE AMS 5922. Additional S53 property data is available in the CINDAS LLC Aerospace Structural Materials Data demo (under "Typical Material PDF Files).

Applications can include aircraft landing gear, driveshafts, rotorshafts, fasteners, and other highly-loaded components that can benefit from increased resistance to corrosion, corrosion fatigue and SCC. S53 landing gear without cadmium plating has been flying since Dec. 2010 (see p. 28 of AA&S presentation below).

Want greater toughness, higher SCC resistance, and can accept lower corrosion resistance? See Ferrium M54.

Benefits

Benefits of using S53 vs. 300M, 4340 and other incumbent materials can include:

• Eliminate or reduce the need for toxic cadmium plating, in order to reduce EHS impact and expenses for both initial installation and on-going re-application. A primer and paint protection scheme on S53 performs comparably to that of a cadmium, chromate, primer and paint protection scheme on 4340 or 300M after 500 hours of salt fog testing per ASTM B117 (see below).
• Reduce general corrosion and related expenses for part condemnation and equipment/system failure.

• Reduce the occurrence of difficult-to-predict SCC failures, and related expenses for part condemnation and equipment failure/downtime.

• Improve resistance to fatigue and corrosion fatigue.
• Reduce specific manufacturing costs, because the high hardenability of S53 permits less severe quench conditions for a given part section size and typically results in less part distortion during heat treatment.

Licensed Suppliers / S53 Price and Availability

As shown at left please directly contact both of our commercial production/sales licensees, Carpenter Technology Corp. and Latrobe Specialty Metals Company, for S53 material pricing, availability and information.

Technical Assistance

If you have a specific application engineering or technical question that is not answered by our licensee's resources and the additional information below, then feel free to Contact Us.

Design and Development Background

We computationally designed S53 in direct response to and with the financial support of the U.S. Strategic Environmental Research and Development Program (http://www.serdp.org), in order to help reduce the use of toxic cadmium on 300M landing gear in the DoD and elsewhere. We won a "Pollution Prevention Project of the Year" Award from SERDP/ESTCP for designing S53. The article in Advanced Materials and Processes magazine attached below provides significant additional background information.

We're currently serving the U.S. Army and U.S. Air Force under a multi-year Cooperative Agreement in order to qualify landing gear and other components produced from S53.

We're currently also working under a NAWCAD-funded SBIR Phase II program to demonstrate S53 as an impoved steel vs. 4340 for U.S. Navy helicopter rotor shafts (i.e. masts), and specifically on the MH-60S helicopter designed and manufactured by Sikorsky Aircraft Corp. The overall objective of this project is to reduce life-cycle and maintenance costs of Navy helicopter masts by increasing fatigue life and reducing corrosion.

In 2011 we co-authored a technical paper that evaluated protection schemes for ultrahigh-strength steels (including S53) for landing gear applications. The paper concluded that a primer and paint protection scheme on S53 is comparable to that of a cadmium, chromate, primer and paint protection scheme on 4340 or 300M, after 500 hours of salt fog testing per ASTM B117; comparative data for zinc-nickel protection schemes was also presented (see below).

In 2008 the A- and B-basis design allowables were included in MMPDS.

In 2008 SAE International issued AMS 5922 specification for S53.