Abstract
This work studied the effect of processing on the elevated-temperature [728 K (455 °C)] fatigue deformation behavior of Ti-6Al-4V-1B for maximum applied stresses between 300 to 700 MPa (R = 0.1, 5 Hz). The alloy was evaluated in the as-cast form as well as in three wrought forms: cast-and-extruded, powder metallurgy (PM) rolled, and PM extruded. Processing caused significant differences in the microstructure, which in turn impacted the fatigue properties. The PM-extruded material exhibited a fine equiaxed α+β microstructure and the greatest fatigue resistance among all the studied materials. The β-phase field extrusion followed by cooling resulted in a strong α-phase texture in which the basal plane was predominately oriented perpendicular to the extrusion axis. The TiB whiskers were also aligned in the extrusion direction. The α-phase texture in the extrusions resulted in tensile-strength anisotropy. The tensile strength in the transverse orientation was lower than that in the longitudinal orientation, but the strength in the transverse orientation remained greater than that for the as-cast Ti-6Al-4V. The ratcheting behavior during fatigue is also discussed.
| Original language | English |
|---|---|
| Pages (from-to) | 3046-3061 |
| Number of pages | 16 |
| Journal | Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science |
| Volume | 42 |
| Issue number | 10 |
| DOIs | |
| State | Published - Oct 2011 |
Funding
The authors are grateful to Dr. S. Tamirisakandala (FMW Composites, Inc.) and Dr. D.B. Miracle (Air Force Research Laboratory) for providing the material used in this study as well as their helpful technical support and guidance. The authors are also grateful to Dr. Stuart Wright (EDAX-TSL, Inc.) for technical assistance with the EBSD acquisition and analysis. A portion of this research work was performed at the ORNL SHaRE User Facility, which is supported by the Division of Scientific User Facilities, Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy. In particular, Mr. Larry Walker and Ms. Kathy Thomas are acknowledged for their technical assistance with the microprobe data collection and TEM sample preparation, respectively. Dr. Yukinori Yamamoto is acknowledged for his assistance with sample preparation for mechanical testing. The authors are also grateful to Messrs. Jerome Lebouef, Derek Miller, and Bryan Kuhr of Michigan State University for their technical assistance.