Present study investigated the effects of austenitizing temperature, austempering temperature and isothermal transformation time on the short fatigue crack growth behavior of nodular cast irons. The crack growth results of short and long fatigue cracks are compared. The influence of stress ratio is evaluated. Fracture surfaces are observed through a scanning electron microscopy to understand the fracture mechanism. The results show that: (1) The nodular cast iron austempered at 350°C has the best resistance to short fatigue crack growth, 400°C and 450°C are the second, and 300°C and 275°C are the worst. (2) The optimum austempering heat treatment process against short fatigue crack growth is to austenitize at 900°C for 1 hr, then austemper at 350°C for 30 min to 4 hr. (3) The short fatigue crack growth rate of austempered nodular cast iron increases with stress ratio.
|Number of pages||7|
|Journal||Journal of the Chinese Society of Mechanical Engineers, Transactions of the Chinese Institute of Engineers, Series C/Chung-Kuo Chi Hsueh Kung Ch'eng Hsuebo Pao|
|State||Published - Feb 1992|