PSI - Issue 19

Kiyotaka MASAKI/ Structural Integrity Procedia 00 (2019) 000–000

6

Kiyotaka Masaki / Procedia Structural Integrity 19 (2019) 168–174

173

(c) AZ80

Fatigue strength at 10 8 cycles

Static strength [MPa] 

Estimated fatigue limit  w(est) [MPa]

First horizontal stress in the two-step bending S-N curve

Minimum stress at which test specimen fatigued

8  140 [MPa]

150 [MPa]

120 [MPa]

 wh 

 w10

 

wL 

 w(est) /  w10 8

 w(est) /  wh

w(est) /  wL

223 0.54 x  0.2T 168 0.87 x  0.2C

120 146 168 130

0.80 0.97 1.12 0.86

0.86 1.04 1.20 0.93

1.00 1.22 1.40 1.08

 0.2T  0.2C

1.0 x  0.2C

341 0.38 x  BT

 BT

compressive 0.2 % proof strength shown in Table 3(a). And then, the best correlation of the AZ61 material was the same as AZ31 material too, shown in Table 3(b). On the other hand, the best correlation of the AZ80 material was the relationships between the minimum stress at which test specimen fatigued (  wL ) and estimated fatigue limit using tensile 0.2 % proof stress shown in Table 3(c). However, the estimated result with 0.2% compression strength is much higher than the experimental value. It is very dangerous to use this estimation result for machine design. Relatively good relation for all materials was the relationship between the minimum stress at which test specimen fatigued (  wL ) and estimated fatigue limit using tensile strength. Estimate value of fatigue limit for all materials was within ± 10 % of the experimental value. The rotating bending fatigue tests were conducted using three kinds of Mg alloys AZ31, AZ61, and AZ80, and the fatigue characteristics including the ultra-high cycle area were investigated. In addition, the correlation between static strength and fatigue limit was investigated by conducting a literature survey. 1. In the past literature survey, positive correlation was confirmed between fatigue limit and static strength characteristics. 2. The fatigue limit of AZ31 and AZ61 roughly matches the compressive 0.2 % proof stress of material. 3. The fatigue limit of AZ80 is clearly lower than the compressive 0.2 % proof stress and the estimated fatigue limit from its value is very dangerous side. 4. The best correlation among all materials was found between the tensile strength and the fatigue limit. The rotating bending fatigue limit can be approximated by  w =0.38  BT using the static tensile strength of material. Acknowledgements This research was conducted as a part of the research of "Super High Cycle Fatigue Research Committee" at the Japan Society of Materials Science, Fatigue Division Committee. Many thanks to the members of the committee. Asahina, T., Katoh, K., Tokisue, H., 1994. Fatigue Strength of Friction Welded Joints of AZ31 Magnesium Alloy, Journal of Japan Institute of Light Metals 44, 147 – 151. Hirukawa, H., Furuya, F., 2010. Fatigue Properties of Extruded AZ61 and AZ31 Magnesium Alloys, Transactions of the Japan Society of Mechanical Engineers A76, 1643 – 1650. Kato, H., Tozawa, T., 1981. Fatigue Fracture of Mg-Al-Zn Alloys, Journal of Japan Institute of Light Metals 31, 240 – 247. Kitahara, Y., Ikeda, K., Shimazaki, H., Noguchi, H., Sakamoto, M., Ueno, H., 2006. Fatigue Strength Characteristics of Non-combustible Mg Alloy : 1st Report, Quantitative Comparison Among Fatigue Strengths of Three Non-combustible Mg Alloys, Transactions of the Japan Society of Mechanical Engineers A72, 661 – 668. Morita, S., Tanaka, S., Nakahara, M., Ohno, N., Kawakami, Y., Enjoji, T., 2009. Cyclic Deformation Behavior and Fatigue Properties of Extruded AZ31B Magnesium Alloy, Journal of Japan Institute of Light Metals 59, 548 – 554. Nakamura, T., Ueno, A., Matsumura, T., Masaki, K., Oguma, H., Akebono, H., Kakiuchi, T., Kikuchi, S., Nakamura, Y., Nishida, T., Ogawa, T., Oguma, N., Sakai, T., Shimamura, Y., Shiozawa, K., Uematsu Y., 2017. Data Acquisition for Very High Cycle Fatigue of Non-ferrous Metallic Materials Based on the Collaborative Research in JSMS -1st report: outline of round-robin experiments on aluminum die casting, beta titanium, and wrought magnesium alloys - 7th International Conference on Very High Cycle Fatigue. Dresden, Germany, 167–173. 5. Conclusions References