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Robust Metal Alloys

Oak Ridge National Laboratory (ORNL)

New High Temperature, Corrosion-Resistant Cast Alloy For Operation in Industrial Gaseous Environments

Program: 
ARPA-E Award: 
$3,900,000
Location: 
Oak Ridge, TN
Project Term: 
04/05/2016 to 04/04/2020
Project Status: 
ACTIVE
Technical Categories: 
Critical Need: 

Many industrial processes involve contact between an alloy and an extreme environment. For example, high-temperature cast iron-based alloys containing chromium and nickel, also called austenitic stainless steels, are used to contain and transport reactants and products for high-temperature chemical reactions in energy production and chemical processes. These alloys are exposed to high temperatures, high pressures, and aggressive chemical environments. Typically, these alloys have been designed to form a coating of chromium oxide, or chromia scale, which protects the alloy from the environment. The alternative to using alloys protected by a chromia scale is to use alloys protected by an aluminum oxide coating, or alumina scale. While an alumina scale offers superior corrosion resistance in many environments, commercial development of affordable alumina-forming cast alloys has not advanced as quickly as those containing chromium due to more complex balance of phase stability and corrosion/oxidation resistance demanded by this class of alloys.

Project Innovation + Advantages: 

The team led by Oak Ridge National Laboratory (ORNL) will develop new cast alumina-forming austenitic alloys (AFAs), along with associated casting and welding processes for component fabrication. ORNL and its partners will prototype industrial components with at least twice the oxidation resistance compared to current cast chromia-forming steel and test it in an industrial environment. These innovations could allow various industrial and chemical processing systems and gas turbines to operate at higher temperatures to improve efficiencies and reduce downtimes, thus providing cost and energy reductions for a wide range of energy-intensive applications.

Potential Impact: 

If successful, ORNL's new cast alumina-forming alloys could provide a more energy-efficient effective alternative to chromia-scale alloys.

Security: 

If successful, ORNL's technology will ensure better chemical safety by advancing corrosion-resistant technologies. ORNL technologies would also allow corrosion resistant alloy production using more domestically available resources, by reducing the use of chromium, which is most commonly imported.

Environment: 

This technology will greatly improve the efficiency of chemical processing systems and gas turbines, ultimately increasing efficiency for a wide range of energy-intensive applications, such as in heat exchangers.

Economy: 

This technology will enable production of longer lasting cast industrial components that will reduce costs and improve productivity by reducing down-time to replace worn components in many different energy production and chemical process applications.

Innovation Update: 

(As of May 2018)
During its award, the team tested over 60 formulations of its alumina-forming alloys and then selected optimized versions with the high temperature strength for ton-scale production. The team developed unique formulations that utilize the minimum amount of aluminum required for scale formation in the alloy (up to 4-5% by weight). The alloy is then stabilized by adding niobium, titanium, zirconium, and other elements to prevent the formation of aluminum nitride during melting and achieve the best properties for industrial use. The resulting alloy demonstrates tenfold oxidation resistance and twice the resistance to “creep” (sagging under structural loads at high temperatures) compared to chromia-forming alloys.

 

The team identified furnace rolls for steel production as a first application and ArcelorMittal as a potential end-user. In April 2017, ArcelorMittal began testing a prototype roll in a 200-foot plate austenitizing furnace. After 4,000 hours at 900C°, the roll showed no signs of appreciable degradation. Under similar conditions, rolls made of today’s commercial alloys have to undergo periodic maintenance to remove oxide layers due to corrosion, resulting in furnace downtime and production losses. Sales of these novel furnace rolls are anticipated to begin in early 2018.

 

For a detailed assessment of the ORNL project and impact, please click here.

 

Contacts
ARPA-E Program Director: 
Dr. David Tew
Project Contact: 
Dr. Govindarajan Muralidharan
Partners
University of Wisconsin-Milwaukee
Release Date: 
11/23/2015