Fatigue of Ultra-Fine Grained α-Brass

Abstract:

Combined methods to obtain ultra-fine grain (UFG) α-brass samples are proposed. Severe plastic deformation followed by recrystallization was conducted, where multiple rolling and equal channel angular pressing (ECAP) were employed. Recrystallization was accomplished by heat-treatment after the severe plastic deformation, and the grain size after the severe plastic deformation was decreased. By multiple rolling, plates with thickness of 0.1 mm and grain size of 1.0 μm were obtained. By ECAP process, square bar with cross-section of 6 mm × 6 mm and minimum grain size of 4.1 μm was obtained. The 0.2 % proof strength, ultimate tensile strength, and fatigue limit were increased with the value of inverse square root of grain size (Hall-Petch relationship). Then, the 0.2 % proof strength of UFG brass was tenfold, the ultimate tensile strength and the fatigue limit were two fold increases from the conventional α-brass. Because of the high strength, the scatter of fatigue strength of UFG brass was large, which reflects the sensitivity to defects in material.

• Periodical: Advanced Materials Research (Volumes 891-892)
• Pages: 1125-1130
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.891-892.1125
• Online since: March 2014
• Authors: Yoshikazu Nakai*, Takuto Imanaka, Daiki Shiozawa
• Keywords: ECAP, Fatigue, Hall-Petch Relationship, Thin Plate, Ultrafine Grain, α-Brass

References

[1] Y. Nakai, A. Hashimoto, and A. Taketani, Development of Fatigue Test Method and Size Effect of Fatigue Strength in Metallic Thin Wires, Journal of the Society of Materials Science, Japan, 54 (2005) 284-289.

DOI: 10.2472/jsms.54.284

[2] N. Miyabe, H. Tanaka, Y. Nakai and T. Nakamura, Effect of Yield Phenomenon on Fatigue Damage in Commercially Pure Iron Thin Wires, Transactions of the Japan Society of Mechanical Engineers. A, 77 (2011) 2098-2106.

DOI: 10.1299/kikaia.77.2098

[3] Handbook of Plastic Forming, The Japan Society for Technology of Plasticity, Corona Publishing, Co. Ltd., Tokyo, 2006, pp.62-63.

[4] Y. Iwahashi, J. Wang, Z. Horita, M. Nemoto, and T. G. Langton, Scripta Materialia, 35 (1996) 143-146.

[5] T. Yamada, K. Hatanaka, and Y. Hirose, Effect of Grain Size on Cyclic Stress-Strain Relation and Fatigue Strength of Copper and α-Brass, Journal of the Society of Materials Science, Japan, 22 (1973) 335-341.

DOI: 10.2472/jsms.22.335

[6] Y. Nakai and T. Kusukawa, Quantitative Evaluation of Slip-Band Growth and Crack Initiation in Fatigue of 70-30 Brass by Means of Atomic-Force Microscopy, Transactions of the Japan Society of Mechanical Engineers A, 67 (2001) pp.476-482.

DOI: 10.1299/kikaia.67.476

[7] Y. Nakai and T. Kusukawa, N. Hayashi, Scanning Atomic-force Microscopy on Initiation and Growth Behavior of Fatigue Slip-Bands in α-Brass Fatigue and Fracture Mechanics: 32nd Volume, ASTM STP 1406, R. Chona, Ed., American Society for Testing and Materials, West Conshohoken, PA, 2002, pp.122-135.

DOI: 10.1520/stp10587s