Low temperature mechanical behavior of microalloyed and controlled-rolled Fe-Mn-Al-C-X alloys
- PDF / 550,719 Bytes
- 5 Pages / 612 x 792 pts (letter) Page_size
- 19 Downloads / 179 Views
REFERENCES 1. I. Ohnaka and T. Fukusako: Trans. IS1J, 198t, vol. 21, pp. 485-94. 2. M. Simpson and M.C. Flemings: Metall. Trans. A, 1984, vol. 15A, pp. 2095-97. 3. R. Mehrabian. M. Keane, and M. C. Flemings: Metall. Trans., 1970, vol. 1, pp. 1209 20. 4. J.A. Stratton: Electromagnetic Theory, McGraw-Hill, New York, NY, 1941, pp. 208-15. 5. K. Suzuki and K. Taniguchi: Trans. 1S1J, 1981, vol. 21, pp. 235-42. 6. J.P. Gabathuler and F. Weinberg: Metall. Trans. B, 1983, vol. 14B, pp. 733-41.
induction melted and were subjected to controlled hot rolling after soaking at 1250 °C for 2 hours. The final reduction ratio was 25 pct and the finishing temperature was 800 °C. Figure 1 shows results of tensile test at RT, - 4 0 °, - 100°, and - 1 9 6 °C, and also includes data reported by Charles et a l . 1 for the cold rolled and recrystallized base alloy. As shown in Figure 1, the yield stress of alloy A at - 1 9 6 °C increased from 600 MPa in the recrystallized condition to 855 MPa by applying the controlled hot rolling process. This remarkable increase in strength is due primarily to the refinement of grain size and dislocation substructure following the controlled rolling process. The ASTM grain size was 11 for the controlled hot rolling compared with ASTM 4 for the recrystallized condition. Niobium was found to be a more potent strengthening microalloying element compared to vanadium. At - 196 °C, the yield stress of alloy B (0.1 Nb) was 944 MPa, compared with 907 MPa for alloy C (0.1 V). The yield and tensile strengths of alloys B and C were equal to those of the 9 wt pct Ni cryogenic steel, while the impact energy of the alloy B was twice that of the 9 wt pct Ni cryogenic steel, 2 as shown in Figure 2. An interesting observation in this study was the increase in elongation with decreasing temperature, as shown in Figure 3. For example, alloy B had 29 pct strain at RT, compared to 57 pct at - 1 9 6 °C. This inverse ductility behavior is ideal for cryogenic material requirements. The reversing behavior was also observed in the recrystallized Fe-Mn-AI-C alloy, l In general, alloys A, B, and C possessed very high elongations. Figure 4 shows the configuration of tensile tested samples before and after testing at RT, - 4 0 °, - 100°, and - 196 °C
0 Fe-Mn-AI-C(AIIoy A) [] Fe-Mn-AI-C-Nb(AIIoy B)
1200 E ~ IlOC
-
Z& Fe-Mn-AI-C-V(AIIoy C) UTS -
lOOC Q L
Low Temperature Mechanical Behavior of Microalloyed and Controlled-Rolled Fe-Mn-AI-C-X Alloys YOUNG G. KIM, YEE S. PARK, and JAE K. HAN
YS
rl
900 CO
o 80C 05 (f)
This work is concerned with the development of high strength-high toughness cryogenic Fe-Mn-A1-C-X alloys containing 0.1 wt pct Nb or 0.1 wt pct V as microalloying elements, and which are processed by a controlled hot rolling process. The base alloy composition was Fe-30Mn-5A10.3C (alloy A), ~ to which 0.1 wt pct Nb (alloy B) and 0.1 wt pct V (alloy C) were added. The alloys were vacuum YOUNG G. KIM, Professor, and JAE K. HAN, Graduate Student, are with the Department of Materials Science and Engineering, Korea Ad
Data Loading...
