Development of New Steel Alloy to Reduce Core Losses in Electric Motors Steel alloy containing silicon, aluminum, chromium, and manganese has the potential to increase electric Once laboratory-scale evaluation of the new steel alloys is completed, limited motor efficiency manufacturing trials will be conducted at AK Steel’s production facilities in Zanesville, Ohio (pictured) and Butler, Pennsylvania. Photo credit AK Steel Corporation. Energy losses in electric motors can be divided into five major categories: core, windage and friction, stator, rotor, and stray load losses. In order to improve a resistivity level comparable to 6.5% Si • When combined with other efficiency motor efficiency, these different types of without undue degradation of mechanical improvements in electric motor losses need to be reduced. Core losses, properties of the steel. The project seeks technologies, these enhancements will which are caused by the magnetization of to identify the promising compositions contribute to the development of a new the electrical steel in the motor core, are for a new alloy, conduct manufactur- generation of electric motors and a significant portion of the total losses. ability testing and assess its performance generators, improving the global These losses occur during low load in motor demonstration testing. competitive advantage of U.S. conditions and during high frequency industry. operation. To reduce high frequency core Benefits for Our Industry and Applications in Our Nation’s losses in a cost effective manner, inex- Our Nation Industry pensive means to increase the resistivity The Department of Energy (DOE) The new material being developed of soft magnetic materials (electrical estimates that the development of cost- will result in higher efficiency motors steel) need to be developed. effective soft magnetic materials with suitable for a wide range of applica- This project seeks to reduce core losses increased resistivity have the potential tions, including relatively slow speed, in electric motors and power generators to reduce core losses in electric motors high torque density systems such as through the development of a new steel and generators by approximately 37%. large commercial and industrial fans alloy containing silicon (Si), aluminum Potential benefits from such efficiency and manufacturing line conveyers. (Al), chromium (Cr), and manganese improvement include: Moderate and high-speed applications, (Mn). Today, the typical electrical steels such as in-wheel motors in transportation • Energy savings of over 2,100 gigawatt used in motor cores contain up to 3.2% systems, will also benefit from the new hours (GWh) per year in the industrial of Si with lower levels of other alloying technology. Electronically controlled high sector, or 0.37% of total energy annu- elements such as Al and Mn. Raising the efficiency motors for the blowers and ally consumed in industrial motors. Si content of the steel increases its resis- fans used in the heating, ventilation, and air conditioning (HVAC) systems is the tivity and, at 6.5% Si, the steel exhibits • Energy savings of 9,700 GWh per year largest potential market for the new mate- superior soft magnetic properties. in non-industrial motors, or 1.27% of rial and motor designs. The improved However, such high Si contents make total energy annually consumed by motors will also be suitable for hermetic the steel increasingly brittle both during such motors. manufacturing of the steel and processing compressors used in HVAC systems. of finished steel into motor laminations. It • Energy savings of 0.44% of total is expected that a more complex Si-Cr- United States electricity consumption. Al-Mn steel alloy can be used to achieve ADVANCED MANUFACTURING OFFICE ADVANCED MANUFACTURING OFFICE Project Description Once a promising alloy (or alloys) have Technology Transition The project objective is to evaluate and been identified, its manufacturability will The project team is in a good position to demonstrate the potential energy savings be evaluated in industrial scale trials. At commercialize the developed Si-Cr-Al- and manufacturability of Si-Cr-Al-Mn least two industrial heats will be melted, Mn steel alloy. AK Steel is the only full- steel alloys for use in electric motor and continuously cast, and processed. The range producer of silicon electrical steels generator cores. The goal is to develop mechanical, microstructural, thermal, in North America. Regal Beloit a new alloy with high specific resistivity electrical, and magnetic properties of Corporation, a member of the project while maintaining desired mechanical the produced steel will be analyzed. The team, is a large U.S. manufacturer of properties of the material. Various alloy generated magnetic property data will industrial and commercial motors. If the compositions will be evaluated for their be used for motor design and optimiza- developed alloy meets established magnetic and mechanical properties and tion. Based on the composition of the perfor-mance and cost targets, both manufacturability. The performance of new alloy and developed manufacturing project partners will work to introduce the developed Si-Cr-Al-Mn steel alloy process, a manufacturing cost analysis the new product to the market. will be demonstrated in 5 horsepower will be conducted. (hp) [3.7 kW] induction motors and In the last phase of the project, Project Partners compared to conventional commercially performance of the new alloy will be AK Steel Corporation available steels. demonstrated in 5 hp [3.7 kW] induction West Chester, OH motors. If modeling provides promising Principal Investigator: Jerry Schoen Barriers performance results, actual test motors Email: [email protected] • Reduced ductility due to higher silicon will be manufactured and evaluated. content of electrical steel, making it Oak Ridge National Laboratory difficult to process, cold reduce or Milestones Oak Ridge, TN stamp laminations without material This 3 year project began in 2017. Regal Beloit Corporation fracturing. Fort Wayne, IN • Process and evaluate several laboratory • Performance or manufacturability of heats of Si-Cr-Al-Mn steel alloys to new alloy(s) may exhibit undesirable or optimize their mechanical, electrical, For additional information, unforeseen characteristics. and magnetic properties (2018). please contact Steve Sikirica • Manufacturing a more complex steel • Conduct industrial-scale trials Technology Manager alloy increases its cost. encompassing melting, continuous U.S. Department of Energy slab casting, hot and cold rolling, Advanced Manufacturing Office Pathways and annealing to produce steels with Phone: (202) 586-5041 optimized metallurgical and magnetic In the past, AK Steel Corporation has Email: [email protected] used different processing methods to characteristics (2019). manufacture steel with higher silicon • Determine manufacturing cost for the content. The company has also experi- developed steel alloy (2019). mented with other materials, such as Cr, in its steel alloys. Building on this • Conduct electromagnetic modeling and experience, the project team will evaluate testing to demonstrate the performance different compositions of steel alloys of the new steel alloys in 5 hp induc- containing Si, Al , Cr, and Mn. The tion motors (2020). project’s goal is to identify a steel alloy that exhibits high resistivity—at least 80 micro-ohm-centimeter (µΩ-cm)—and good mechanical properties. For more information, visit: energy.gov/eere/amo DOE/EE-1578 • November 2017.