Fatigue and Facture Toughness Characteristic of Al{sub}18B{sub}4O{sub}33 w/AC4CH Composites for Lightweight Automobile Engine

摘要

The objective of this study is to investigate fatigue life, fatigue crack growth rate and fracture toughness on AC4CH alloy reinforced with aluminum borate whisker. The experiment of fatigue life have been carried out for the stress ratio R=0.1 at 20 Hz. The results indicated that fatigue life limit of Al{sub}18B{sub}4O{sub}33 w/AC4CH is about 71% higher than fatigue life limit of AC4CH alloy. FCGR test on half-size CT specimen of width 25 mm, thickness 12.5 mm were conducted by using sinusoidal waveform. Test conditions were at 0.1 and 0.05 load ratio at 10 Hz of loading frequency and test load was 2.3 kN. The effect of stress ratio on the FCGR were discussed based on the Paris law. As results of FCGR, that was increased with increasing the load ratio. As the results of fracture toughness, fracture toughness (KIC) of Al{sub}18B{sub}4O{sub}33 w/AC4CH is 8.7 Mpa-m{sup}0.5 but AC4CH alloy was violated the criteria stipulated by ASTM standard for a valid measurement of KIC. In case of the requirements for plane strain were not met. The results of fracture toughness have been verified by the standard measurement of JIC values. That was performed in accordance with ASTM E 1820 standard method. Consequently, it was converted JIC into KIC.