QuesTek Innovations LLC, Evanston, Ill., introduces QT 17-4 powder, a stainless steel composition for powder bed fusion additive manufacturing parts for service in either the as-printed condition or applications requiring only a single low-temperature heat treatment.
The development of QT 17-4 powder is significant because it allows for AM production of complex, high-strength stainless steel parts comparable to wrought 17-4 PH, but without the need for expensive cryogenic processing or high-temperature heat treatment. The project has been funded by the U.S. Navy Small Business Innovation Research program.
Commonly used 17-4 steel in AM often requires higher-cost argon-atomized powder to avoid retained austenite issues, and it yields poor properties; however, even properties of argon-atomized 17-4 properties fluctuate widely and are sensitive to the feedstock composition.
According to Dr. Dana Frankel, QuesTek Manager of Design and Product Development, “With QuesTek’s QT 17-4 powders, a fully martensitic microstructure is achieved in the as-printed condition. The high-temperature solution heat treatment process, required for conventional 17-4, is not needed for QuesTek’s alloys, and the resulting properties have less variation.”
Two feedstock options are available: QT 17-4 for service in the direct aged condition, and QT 17-4+ for use in the as-printed condition. The corrosion resistance and fatigue performance of both designed AM alloys are equivalent or improved over AM material printed with commercially available 17-4 powders.
QuesTek’s new 17-4 powders can be used in a wide range of industries, including aerospace, defense, medical, chemical processing and energy. QuesTek’s powder was developed using its proven Integrated Computational Materials Engineering (ICME) technologies and Materials by Design® approach.
Although QuesTek’s initial effort has focused on powder-based additive manufacturing, its engineers plan to demonstrate one or more wire-based AM processes to enable larger component production at lower cost.
