Steelmaking method increases high-temperature strength
Steelmaking method increases high-temperature strength
Keywords Steel,Yield strength
A steelmaking technology known as the Rhondite process, which involves different thermodynamic parameters from those in conventional steelmaking, reportedly produces high-temperature properties that may enable it to replace cobalt-base alloys in some aerospace applications. The process was developed by MicroMet Technology, Charlotte, North Carolina, and has been licensed for aerospace and gas turbine applications by BFGoodrich Aerospace, Troy, Ohio.
According to BFGoodrich,the material can improve wear, strength, and hardness in iron-based materials. For example, the yield strength of cast Rhondite A286 is about 480MPa (70ksi) at room temperature, while yield strength of Stellite 21 is about 550MPa (80 ksi). At 260°C (500°F), the Rhondite material and Stellite have very nearly the same yield strength of about 480MPa. However, at 540°C (1,000°F),strength of Rhondite is still about 480MPa, while Stellite strength has dropped below 410 MPa (60 ksi). At 790°C (1,450°F), both have the same strength of about 275 MPa (40ksi). Charpy impact strength of Rhondite A286 is 34J at 55°C, 25J at 22°C, and 20J at 93°C (25ft-lb at65°F, 18ft-lb at 72°F, and 15ft-lb at 200°F). By comparison, Stellite 21 is about 14J (10ft-lb) at each temperature.
Compared with conventional cast AISI stainless steel alloy 304, Rhondite cast alloy has a yield strength of about 340 MPa (55 ksi), while that of conventional alloy 304 is 275 MPa (40ksi). At 540°C (1,000°F), yield strength of Rhondite 304 is 200 MPa (30ksi),while that of conventional alloy 304 is only 140MPa (20ksi).
As these properties show,enhanced alloys can be used to increase performance of aerospace components. Costs could be reduced by substituting a conventional steel processed by the Rhondite method for an expensive alloy such as cobalt-base Stellite 21. The company is currently building a database of materials properties. Supporting material development are Purdue University, West Lafayette, Indiana, and Case Western Reserve University, Cleveland, Ohio, as well as Precision CastParts Corp., Portland, Oregon. According to BFGoodrich, some parts are expected to be in production within a year.
For further details contact BGGoodrich Aerospace, 101 Waco St, PO Box 340, Troy, Ohio 45373. Tel: +1 800 287 8909.
