Grain Refinement for Strengthening in Fe 3 Al-based Alloys through Thermomechanical Processing
- PDF / 1,591,878 Bytes
- 6 Pages / 595 x 842 pts (A4) Page_size
- 50 Downloads / 178 Views
1128-U02-03
Grain Refinement for Strengthening in Fe3Al-based Alloys through Thermomechanical Processing Satoru Kobayashi1 Akira Takei2 and Takayuki Takasugi1,2 1 Osaka Center for Industrial Materials Research, Institute for Materials Research, Tohoku University, 1-1Gakuen-cho Naka-ku, Sakai, Osaka 599-8531, Japan 2 Department of Materials Science, Graduate School of Engineering, Osaka Prefecture University, 1-1Gakuen-cho Naka-ku, Sakai, Osaka 599-8531, Japan ABSTRACT A thermomechanical process (TMP) for grain refinement was performed in bulk Fe3Al-based alloys containing ~10% volume fraction of κ-Fe3AlC precipitates. In the TMP, κ particles play an important role in reducing the inhomogeneity of recrystallization due to the matrix orientation. The grain size was refined to ~20 µm by optimizing the κ particle size. A fine-grained and pancake/recovered microstructure fabricated by the TMP showed more than 1200 MPa tensile strength and 8% tensile ductility at room temperature in air. The tensile strength of this material was higher than those of conventional wrought Fe3Al alloys at temperatures between room temperature and 500 ˚C, and the specific tensile strength was as high as that of the Ti-6Al-4V alloy at temperatures above 400 ˚C. INTRODUCTION Fe3Al-based intermetallic alloys have received attention so far as candidates for high temperature structural materials because of their excellent oxidation and sulphidation resistance at high temperatures, ubiquitous raw material and low density compared with conventional stainless steels and heat resistant alloys [1,2]. Research and development studies on these alloys were mainly focused on the following two issues: the improvement of (1) the limited room temperature ductility and strength by modification of the grain structure, the order state, surface conditions and alloying [3-6] and (2) poor high temperature properties by alloying through precipitation and/or solid solution strengthening [7-11]. Improvement of the room temperature ductility and strength was greatly achieved through a thermomechanical (warm rolling + annealing) process to produce pancake-shaped grains in which dislocations are well recovered [3-6]. Grain refinement (GR) is, on the other hand, a generally accepted fabrication process to improve strength and toughness in materials. GR was achieved in FeAl alloys through powder metallurgy (PM). PM manufactured Fe-40Al with very fine grain size (~1 µm) possesses an excellent combination of strength and ductility as well as fatigue properties [12]. However, GR method has not yet been established through wrought process in bulk Fe3Al alloys. We have investigated the texture and recrystallization of warm rolled Fe3Al-based alloys with and without carbide particles [13-16], and have recently achieved to produce fairly homogeneous recrystallized structures with a grain size of ~20 µm in the Fe3Al alloys containing κ-Fe3AlC carbide particles [17]. The content of this paper is two-fold. The first is to present the effects of κ particles on the warm deformation a
Data Loading...
